LRM Abstracts

ArticleAuthorJournalISSN (Electronic)ISSN (Paper)VolumeIssueDatePagesCONTROL (Author)Abstract
Largemouth bass consumption demand on hatchery rainbow trout in two Washington lakesDavid R. Christensen; Barry C. MooreLake and Reservoir Management1040-23810743-81412632010 200 - 211Largemouth bass consumption demand on hatchery rainbow trout in two Washington lakes High mortality (84-89%) of stocked rainbow trout (Oncorhynchus mykiss) in Twin Lakes, Washington, has been partially blamed on predation from non-native largemouth bass (Micropterus salmoides). We examined the gut-content of 434 largemouth bass and applied a bioenergetics model to determine the consumption demand on hatchery-released rainbow trout and other prey species in the Twin Lakes. Largemouth bass consumed approximately 4915 (95% CI; 2393-13,452) fall stocked rainbow trout in South Twin. No rainbow trout consumption was observed in North Twin, despite a similar stocking regime. Approximately 6.3% (95% CI; 3-17%) of total fall stocked rainbow trout in South Twin were consumed by largemouth bass. Rainbow trout stocked in the fall ranged from 100 to 160 mm total length and were all subject to predation by large largemouth bass ≥300 mm. Large largemouth bass consumed rainbow trout that reached up to 210 mm in length and 58% of bass body length. No predation was observed on larger rainbow trout (215-370 mm) stocked during the spring. Smaller largemouth bass ≤299 mm consumed primarily invertebrates, including crayfish, and did not consume rainbow trout in either lake. During spring and summer in South Twin Lake, large largemouth bass consumed principally golden shiner (Notemigonus crysoleucas) and crayfish. In North Twin Lake, golden shiner constituted most of the larger bass diet for the entire year. Differences in macrophyte distribution, bathymetry, temperature and/or predator-prey demographics likely influenced variability in largemouth bass predation between lakes. Largemouth bass predation did not account for overall rainbow trout mortality.
Public preferences and values for management of aquatic invasive plants in state parksDamian C. Adams; Santiago Bucaram; Donna J. Lee; Alan W. HodgesLake and Reservoir Management1040-23810743-81412632010 185 - 193Public preferences and values for management of aquatic invasive plants in state parks Alien invasive plants (AIP) significantly impact the ecology of natural areas and nature-based recreation, yet control programs are chronically underfunded. This study examined Florida residents' willingness-to-pay (WTP) to control aquatic AIP in river and lake state parks through entrance fees. We used a method commonly applied in the nonmarket valuation literature, but not previously applied to AIP, and found that residents have a high WTP to control AIP and are willing to support control programs through entrance fees. In 2007, we surveyed 1299 Florida residents to estimate the impact of AIP on state park recreation. The survey included conjoint choice questions to establish the impact of several park attributes on respondents' economic utility or welfare: abundance of AIP, entrance fees, park facilities, abundance of native plant species, and abundance of native animal species. Using entrance fees as a payment vehicle, we estimated that the typical Florida resident has a per-visit WTP of $6.15 to reduce AIP coverage, $4.41 to improve park facilities, $3.81 to increase the abundance of native plants, and $4.99 to increase the abundance for native animals. We used annual attendance data from 63 river and lake state parks to calculate statewide WTP to control AIP and found that local residents are willing to spend $12.26 million/yr, and all users are willing to spend $35.01 million/yr to keep AIP from becoming “numerous and dense” in the 63 parks. This far outweighs the $26 million/yr that the state is currently spending in all natural areas, including state parks.
Spatial and temporal patterns of nearshore clarity in Lake Tahoe from fine resolution turbidity measurementsMargaret A. Shanafield; Richard B. Susfalk; Kendrick C. TaylorLake and Reservoir Management1040-23810743-81412632010178 - 184Spatial and temporal patterns of nearshore clarity in Lake Tahoe from fine resolution turbidity measurements The nearshore areas of lakes respond quickly to watershed runoff, increases in tributary inflows from annual snowmelt, and increased anthropogenic activity in the basin. Therefore, this area of the lake serves both as an early warning system for water quality degradation and as an indicator of the effectiveness of land management practices or sediment control projects. In this study we evaluated the usefulness of combining fine-scale water quality measurements and discrete particle sample analysis to gain a better understanding of seasonal and spatial trends in the nearshore area of Lake Tahoe. Turbidity and mineral composition at 0.5 m depth were measured in nearshore waters near the City of South Lake Tahoe at a spatial resolution of 5-30 m in 2002 and 2003. Particles filtered from discrete samples collected 200 m from shore were analyzed by scanning electron microscopy and chemical analysis using quantum electron dispersive spectrometry. Baseline turbidity levels were extremely low (0.15 NTU) during calm periods in the fall but rose to levels above 4.0 NTU in response to winter and spring precipitation events and spring snowmelt runoff. Discrete samples collected 200 m from shore contained over 80% organic material during the dry part of the year and at least 50% mineral particles during the winter and spring. The effectiveness of this method for detecting variability in nearshore conditions at Lake Tahoe is promising for monitoring the littoral areas of other pristine lakes facing increased anthropogenic pressure and other watershed disturbances.
Using GIS to estimate lake volume from limited dataJeffrey Hollister; W. Bryan MilsteadLake and Reservoir Management1040-23810743-81412632010194 - 199Using GIS to estimate lake volume from limited data Estimates of lake volume are necessary for calculating residence time and modeling pollutants. Modern GIS methods for calculating lake volume improve on more dated technologies (e.g., planimeters) and do not require potentially inaccurate assumptions (e.g., volume of a frustum of a cone), but most GIS methods do require detailed bathymetric data, which may be unavailable. GIS technology cannot correct for a lack of data; however, it can facilitate development of methods that better use the relatively simple and more widely available measurements of lake shape and maximum depth. In this research note we describe a method to model bathymetry and estimate lake volume with a limited set of data that consists only of a maximum depth measurement and a GIS layer of lake shoreline. Using a simple linear transformation, we estimated depth as a function of distance from shoreline and with the resultant information estimated lake volume. We applied and compared this method with estimates derived from field bathymetry data of 129 lakes in New Hampshire. In New Hampshire lakes, the assumption of depth as a function of distance is appropriate, and the simple GIS method has lower overall error than simply using the formula for volume of a cone to estimate lake volume. This approach has broad implications in the assessment of lake condition from national surveys (e.g., US Environmental Protection Agency's National Lakes Assessment) and should improve upon models of nutrients, contaminants and hydrology, even in the absence of detailed bathymetric data. Supplemental materials are available for this article. Go to the publisher's online edition of Lake and Reservoir Management to view the free supplemental file.
Manganese sources and cycling in a tropical eutrophic water supply reservoir, Paso Bonito Reservoir, CubaCarmen Betancourt; Fanny Jorge; Roberto Suárez; Marc Beutel; Seyoum GebremariamLake and Reservoir Management1040-23810743-81412632010217 - 226Manganese sources and cycling in a tropical eutrophic water supply reservoir, Paso Bonito Reservoir, Cuba Paso Bonito Reservoir (mean depth = 6.5 m; volume = 8.0 106 m3) is a small raw water reservoir in south-central Cuba. This study evaluated sources of high levels of manganese in the reservoir causing taste and odor problems. Watershed monitoring showed that levels of total manganese (Mn) and total iron (Fe) were high (Mn 0.14-0.64 mg/L; Fe 5.3-12.4 mg/L) during the first flood of the wet season in river sampling stations near historical pyrite mining operations. Monitoring in the reservoir showed that Mn and Fe were present in bottom waters throughout the year, with peak levels (>8 mg/L of Mn and >30 mg/L of Fe) coinciding with low levels of oxygen in summer months. Empirical modeling of Mn concentration in the reservoir water column showed that it correlated significantly with Fe (positive correlation), redox potential (negative correlation) and dissolved oxygen (negative correlation). Statistical evaluation of the temporal cycle of Mn in raw water delivered to the Juan Gonzales Water Treatment Plant showed that Mn accumulation was highly seasonal, peaking annually around September when dissolved oxygen in raw water was at a minimum. Data suggest that during first-flood conditions early in the wet season, mass loading of Mn and Fe from the watershed to the reservoir is high. During the subsequent drier low-flow summer period, external mass loading of metals drops dramatically and the reservoir becomes a large exporter of Mn and Fe as the metals are internally recycled under anaerobic conditions in bottom waters.
Food web effects and the disappearance of the spring clear water phase in Onondaga Lake following nutrient loading reductionsRoland W. Wang; Lars G. Rudstam; Thomas E. Brooking; David J. Snyder; Mark A. Arrigo; Edward L. MillsLake and Reservoir Management1040-23810743-81412632010169 - 177Food web effects and the disappearance of the spring clear water phase in Onondaga Lake following nutrient loading reductions The annual spring clear water phase (May-June) in Onondaga Lake, New York, unexpectedly disappeared in 2003 following several years of phosphorus and ammonia loading reductions at the Metropolitan Syracuse Wastewater Treatment Facility (Metro). Mean chlorophyll a concentration during May-June was higher from 2003 to 2007 than from 1990 to 2002, with mean Secchi disk depths <2 m. Large zooplankton (Daphnia sp.) were abundant during April-June before 2003 but were rare from 2003 to 2007, while abundance of small zooplankton (Bosmina longirostris) increased. Alewife (Alosa pseudoharengus) catches from electrofishing surveys dramatically increased in 2003, and hydroacoustic surveys estimated the alewife population to be between 1600 and 2300 fish/ha in spring 2005-2007. The alewife population in 2005 was dominated by a strong 2002 year class. Increasing biomass of the 2002 year class coincided with the timing of the shift from large to small zooplankton in late summer of 2002. This indicates that the strong 2002 alewife year class initiated a classic trophic cascade in Onondaga Lake, causing the decline and continuing low abundance of Daphnia sp. and the disappearance of the spring clear water phase. The increase in alewife may have been associated with decreasing ammonia concentrations following improvement to Metro. Unionized ammonia has been below levels considered toxic to nonsalmonid fish species since 1999, and the ammonia concentration continues to decrease in the lake. Thus, reductions in nutrient loading can lead to unanticipated food web effects causing decreases rather the expected increases in water clarity in the spring-early summer period.
Avoidance of strobe lights by zooplanktonMartin J. Hamel; Nathan S. Richards; Michael L. Brown; Steven R. ChippsLake and Reservoir Management1040-23810743-81412632010212 - 216Avoidance of strobe lights by zooplankton Underwater strobe lights can influence the behavior and distribution of fishes and are increasingly used as a technique to divert fish away from water intake structures on dams. However, few studies examine how strobe lights may affect organisms other than targeted species. To gain insight on strobe lighting effects on nontarget invertebrates, we investigated whether underwater strobe lights influence zooplankton distributions and abundance in Lake Oahe, South Dakota. Zooplankton were collected using vertical tows at 3 discrete distances from an underwater strobe light to quantify the influence of light intensity on zooplankton density. Samples were collected from 3 different depth ranges (0-10 m, 10-20 m and 20-30 m) at <1 m, 15 m and ≥100 m distance intervals away from the strobe light. Copepods represented 67.2% and Daphnia spp. represented 23.3% of all zooplankton sampled from 17 August to 15 September 2004. Night time zooplankton densities significantly decreased in surface waters when strobe lights were activated. Copepods exhibited the greatest avoidance patterns, while Daphnia avoidance varied throughout sampling depths. These results indicate that zooplankton display negative phototaxic behavior to strobe lights and that researchers must be cognizant of potential effects to the ecosystem such as altering predator-prey interactions or affecting zooplankton distribution and growth.
A combined watershed-water quality modeling analysis of the Lake Waco reservoir: I. Calibration and confirmation of predicted water qualityJoseph D. White; Shane J. Prochnow; Chris T. Filstrup; J. Thad Scott; Bruce W. Byars; Lisa Zygo-FlynnLake and Reservoir Management1040-23810743-81412622010147 - 158A combined watershed-water quality modeling analysis of the Lake Waco reservoir: I. Calibration and confirmation of predicted water quality A coupled watershed-reservoir modeling system was applied to the Lake Waco reservoir and watershed to test possible sources of seasonal excess nutrient concentrations in Lake Waco. The Soil Water Assessment Tool (SWAT) was used for modeling watershed production of water and nutrients. This model included small lakes and dairies in the watershed, located spatially using geographic data. For the reservoir, the 2-dimensional, hydrodynamic model CE-Qual-W2 was used with inputs derived from the SWAT simulations. Calibration of the models was based on observed hydrographic information and stream and reservoir nutrient data. The relationship between predicted and observed stream flow values for the North Bosque River, the major tributary to the reservoir, were highly correlated (r2= 0.86) for the calibration period 1997-1998. Predicted daily nutrient values near the inflow of the North Bosque into Lake Waco reservoir were variable but similar to previously estimated annual loading values. Comparison of predicted water quality characteristics from the CE-Qual-W2 model with observed values showed acceptably reliable correspondence seasonally. Chlorophyll-a was used as the main measure for calibration accuracy due to its importance for reservoir management and was predicted to within 6.6% based on the mean percent error or an absolute root mean square error of 9.76 μg/L of observed values. The prediction of stream values from the SWAT model and reservoir nutrient concentrations were sensitive and robust for the next phase of the Comprehensive Lake Waco Study, which includes evaluation of multiple watershed and reservoir management options.
Loading of phosphorus and nitrogen to Lake Waco, TexasKenneth J. WagnerLake and Reservoir Management1040-23810743-81412622010123 - 146Loading of phosphorus and nitrogen to Lake Waco, Texas Cyanobacterial blooms in Lake Waco are linked to nutrient loading from the watershed. Direct measurement of nutrient levels over a period of 8 years facilitates calculation of loading of water, phosphorus (P) and nitrogen (N) to Lake Waco. The North Bosque River (NBR) provides 61% of the flow to Lake Waco, while the Middle Bosque River (MBR) contributes 15.5%. The South Bosque River (SBR) and Hog Creek (HC) each contribute about 7.5% of the total water load to the lake, while other sources contribute less. The lake receives average annual total phosphorus (TP) loading of approximately 147,000 kg and an annual total nitrogen (TN) load of about 1,450,000 kg, with considerable variability expected among years. The NBR contributes 67% of the TP and 37% of the TN. The MBR provides slightly more than 17% of the TP and 41% of the TN. Inputs from SBR are estimated at about 8% of the TP and 10% of the TN. All combined, HC, direct drainage to the lake, atmospheric deposition, ground water inseepage, human inputs associated with recreation, waterfowl inputs and internal loading contribute <8% of the TP and about 12% of the TN. The NBR is clearly the dominant source of TP to the lake, while MBR and NBR contribute roughly equal amounts of TN and much more than any other source. Inputs from wastewater treatment facilities (WWTF) represent about 4% of the TP input and <2% of the TN load to Lake Waco. Despite greater availability of the forms of P in WWTF inputs, this is a minor source for the lake. Inputs from dairy operations, including areas of active animal use and waste application fields, are estimated to contribute 34-42% of the NBR TP load and 23-28% of the overall TP load to Lake Waco. Dairy operations are estimated to contribute about half of the biologically available P load to Lake Waco and generate low N:P ratios in the lake. Despite high loading and resultant blooms, Lake Waco exhibits lower concentrations of P than would be predicted by multiple models, and the actual concentrations stimulate less algal growth than would be expected. In the absence of major inputs related to human activities, the predicted P load to Lake Waco would be less than half the current load, and very little of it would be biologically available. The initial regulatory target of a 50% reduction in P loading to NBR set by the Texas Commission on Environmental Quality is appropriate. If dairy inputs are successfully controlled, measurable improvement can be expected. Supplemental materials are available for this article. Go to the publisher's online edition of Lake and Reservoir Management to view the free supplemental file.
Investigation of benthic phosphorus flux controls in Lake Waco, TexasMarie E. Esten; Kenneth J. WagnerLake and Reservoir Management1040-23810743-81412622010114 - 122Investigation of benthic phosphorus flux controls in Lake Waco, Texas Investigations were completed to quantify the amount of phosphorus (P) available for release from the sediment of Lake Waco, Texas, as part of the Lake Waco Comprehensive Lake Management Study. Sediment oxygen demand and benthic nutrient flux measurements were obtained using an in situ chamber and an in situ nutrient analyzer available from Systea Inc. Sediment samples were also collected to determine the amount of loosely sorbed, iron-bound and total P present in the lake sediments by fractionation. Initial results indicated no orthophosphate, nitrate/nitrite or ammonia flux from the sediments into the water column during incubation periods. Sediment fractionation revealed nondetectable loosely sorbed P, low amounts of iron-bound P and moderate total P present in the sediments. Review of these data and comparison with other research suggests that calcium is responsible for controlling P cycling in Lake Waco. This hypothesis was examined by determining the mineral composition of the sediment samples utilizing X-ray diffraction methods. Results indicated the presence of enough calcium-phosphorus minerals to account for all of the total phosphorus reported in the sediments. Unlike many lakes where iron controls P cycling, release of P from calcium compounds in available forms is negligible in Lake Waco, even under anoxic conditions. Management for reduced water column P levels should focus on watershed sources.
A combined watershed-water quality modeling analysis of the Lake Waco reservoir: II. Watershed and reservoir management options and outcomesJoseph D. White; Shane J. Prochnow; Chris T. Filstrup; Bruce W. ByarsLake and Reservoir Management1040-23810743-81412622010159 - 167A combined watershed-water quality modeling analysis of the Lake Waco reservoir: II. Watershed and reservoir management options and outcomes In this study, calibrated watershed and reservoir models are used to explore a range of possible watershed conditions and potential management options to reduce available nutrients and algal growth in the Lake Waco reservoir. The management options are divided between watershed and reservoir options. The watershed management options include wetland construction, manure haul-off, agriculture conversion to pasture, absolute nutrient retention in the watershed and control of urban nutrient run-off. For the reservoir, management options of phosphorus inactivation and increased algal consumption by grazers were evaluated. For all individual management scenarios, only complete conversion of agricultural lands into rangeland decreased nutrient levels and algae growth significantly and achieved target levels for chlorophyll-a and total phosphorus. Combined management scenarios including wetland construction, manure haul-off from dairy operations and increased in-reservoir herbivory could further reduce chlorophyll-a and nutrient values, but with less efficiency than agricultural conversion alone. The management option study showed that decreasing nutrient inputs and water clarity were important factors for controlling algal growth in Lake Waco, and that substantial reduction in total phosphorus is needed to achieve target conditions.
Lake Waco Comprehensive Study: Background and overviewThomas M. ConryLake and Reservoir Management1040-23810743-8141262201074 - 79Lake Waco Comprehensive Study: Background and overview As a water supply, Lake Waco, Texas, is subject to the provisions of the Safe Drinking Water Act and related regulations. Aside from concern over primary contaminants that affect human health, there have been taste and odor incidents of increasing frequency, duration and severity over the last decade; therefore, this comprehensive study was developed to define historical and existing water quality conditions and to project possible management scenarios. Practical management approaches to maintain or improve existing water quality conditions within the lake and immediate watershed were identified and evaluated for implementation. The declining water quality within the lake necessitated the construction of an additional treatment process at a cost of $40 million to facilitate compliance with newer drinking water regulations. The investigators sought to assess the magnitude and relative size of water and nutrient contributions to Lake Waco, allowing assessment of loading in relation to acceptable levels for maintaining desired conditions in the reservoir. Thirty-five specific tasks (studies) were conducted concurrently, investigating specific issues or mechanisms of interest in relation to the lake, its watershed and its users. The majority of the $2 million study cost was provided by the City of Waco, although the US Army Corps of Engineers, US Environmental Protection Agency, US Geological Survey, and Texas Parks and Wildlife Department made important contributions to the study.
Hot spots and hot moments of planktonic nitrogen fixation in a eutrophic southern reservoirRobert D. Doyle; J. Thad Scott; Margaret G. ForbesLake and Reservoir Management1040-23810743-8141262201095 - 103Hot spots and hot moments of planktonic nitrogen fixation in a eutrophic southern reservoir Reservoirs have been identified as hot spots of biogeochemical activity, although they are known to exhibit pronounced temporal and spatial variability in planktonic community dynamics. Results from this 19-month study at 5 locations on a southern polymictic reservoir identify pronounced temporal (seasonal and interannual) and significant spatial variability in planktonic nitrogen fixation. Planktonic nitrogen fixation was found to be high during the warmest portion of the year and undetectable for most of the rest of the year. Interannual variability between 2 consecutive summer periods was high and likely due to differences in rainfall pattern and resulting differences in ambient nutrient concentrations and flushing rates. Rates during the dry summer exceeded those during the following summer when unexpected summer rains occurred. Spatial differences in areal and volumetric rates were also significant. Volumetric rates were highest in the inflow transition zone of a river draining a watershed impacted by dairy operations, with inflows exhibiting low N:P ratios. Areal rates were highest in the deeper and clearer portions of the reservoir. Areal rates of nitrogen fixation varied among the 5 stations by a factor of 4.4 in the dry summer and by a factor of 22 in the wetter summer.
Sediment transport mechanisms influencing spatiotemporal resuspension patterns in a shallow, polymictic reservoirChristopher T. Filstrup; Owen T. LindLake and Reservoir Management1040-23810743-8141262201085 - 94Sediment transport mechanisms influencing spatiotemporal resuspension patterns in a shallow, polymictic reservoir Although whole-lake sedimentation models have been developed for natural lakes, they may not apply to reservoirs due to differing physical, morphological, and hydrodynamic characteristics along a reservoir's longitudinal axis. We measured sedimentation rates immediately below the photic zone and near the sediment surface in a polymictic reservoir's riverine and lacustrine regions to identify transport mechanisms influencing sediment resuspension during an annual cycle. Lake-wide regression models revealed that wind-induced mixing depths explained <20% of sediment resuspension variability. However, site-specific mixing depth models explained 30% of sediment resuspension variability at a lacustrine station. Inverse relationships between mixing depth and sediment resuspension suggested that wind-induced mixing entrained deep-water advective river sediments into the photic zone rather than resuspending deposited sediments. Maximum mixing depths calculated from strong wind events never exceeded site depths, supporting this hypothesis. Lake-wide and site-specific mixing depth models were not improved by considering short-duration, strong wind events, suggesting that episodic winds did not generate enough momentum to effectively deepen mixing depths. Lake-wide regression models indicated that river discharge (r2= 0.19) was a better predictor of sediment resuspension than mixing depth. Site specific discharge models explained 44% and 30% of sediment resuspension variability at 2 riverine stations, emphasizing the influence of horizontal advection in riverine regions. River discharge and wind-induced mixing influenced sediment resuspension at one sampling station only, indicating that the site may have been located in the transition region. Future reservoir sedimentation models should incorporate weighting factors to appropriately represent sediment transport mechanisms along a reservoir's longitudinal axis.
The Lake Waco Comprehensive Study: PrefaceThomas M. ConryLake and Reservoir Management1040-23810743-8141262201073The Lake Waco Comprehensive Study: Preface
Historical, current, and future economic benefits and costs relating to Lake Waco, TexasThomas M. ConryLake and Reservoir Management1040-23810743-8141262201080 - 84Historical, current, and future economic benefits and costs relating to Lake Waco, Texas Lake Waco is an important economic asset for Central Texas. Since 1964, Lake Waco has been utilized as a multiple-purpose reservoir, providing flood protection (more than $258 million in damages prevented), a public drinking water source for 200,000 Central Texans (the City of Waco Utilities Department budget is $40 million per year), and recreational area by up to 2 million people per year. A rise in the conservation pool level increased the drinking water yield by 26 million cubic meters per year but temporarily interfered with recreation. Despite a drop in recreational usage for several years (2001-2005) and significant increases in the quality and quantity of recreational facilities during the pool rise project, the economic impact to local communities remained between $8 and $27 million dollars per year, depending on the method applied. Results from application of the Money Generation Model Version 2 indicate that approximately 750 local jobs are supported by recreational spending. There is a substantial economic return on investments in the enhancement and protection of Lake Waco.
The use of carbon-utilization profiling to determine sources of fecal contamination in a central Texas watershedMichelle D. Nemec; Rene D. MassengaleLake and Reservoir Management1040-23810743-81412622010104 - 113The use of carbon-utilization profiling to determine sources of fecal contamination in a central Texas watershed The purpose of this research was to characterize the relationship of Escherichia coli isolates from various animals, sewage, and water based on carbon substrate utilization patterns, and to use these patterns to determine the dominant contributors of nonpoint source fecal pollution to a central Texas reservoir from its watershed. We collected 1028 fecal samples from cattle, companion animals, goat, horse, poultry, sewage, sheep, and wildlife, collectively. From these, 1915 E. coli fecal isolates were analyzed. We collected 100 water samples throughout the North Bosque watershed; 910 E. coli water isolates were analyzed. The Biolog system was used to generate a carbon-utilization pattern for each isolate. A dendrogram constructed from the carbon-utilization patterns demonstrated that isolates from the same source category usually clustered together, excluding water isolates that were spread over many clusters. A bacterial-source tracking library was constructed from the carbon-utilization data obtained from the fecal and sewage isolates and analyzed for internal accuracy. Rates of correct classification for the library ranged from 12.8 to 78.6%. The average rate of correct classification for the library was 45.8%, and specificity values were high, ranging from 75 to 99%. When water isolates were submitted to the library for identification, 43 were classified as originating from cattle, indicating cattle were the dominant source of fecal pollution in the watershed. This was followed by sewage at 27%. Based on these data, our first recommendation for decreasing bacterial pollution in this watershed is to implement strategies that can reduce the contribution of fecal contamination from these 2 sources.
Changing water, phosphorus and nitrogen budgets for Valle de Bravo reservoir, water supply for Mexico City Metropolitan AreaJorge A. Ramírez-Zierold; Martín Merino-Ibarra; Emiliano Monroy-Ríos; Monica Olson; Fermín S. Castillo; Margarita E. Gallegos; Gloria VilaclaraLake and Reservoir Management1040-23810743-8141261201023 - 34Changing water, phosphorus and nitrogen budgets for Valle de Bravo reservoir, water supply for Mexico City Metropolitan Area Ramrez-Zierold JA, Merino-Ibarra M, Monroy-Ros E, Olson M, Castillo FS, Gallegos ME, Vilaclara G. 2010. 2010. Changing water, phosphorus and nitrogen budgets for Valle de Bravo reservoir, water supply for Mexico City Metropolitan Area. Lake Reserv. Manage. 26:23-34. Valle de Bravo reservoir (VB) provides water supply to the Mexico City Metropolitan Area and other surrounding cities. Nutrient loading to this reservoir increased 276% for phosphorus (P) and 203% for nitrogen (N) in a single decade. During 2002-2005, P and N mean loadings to VB were 120.8 103 kg P/y and 591.8 103 kg N/y. These loadings were quite variable because of source variations from uncontrolled domestic and agricultural inputs. More than half (56%) of the maximal water storage of the reservoir was withdrawn annually. Water withdrawal removed 22% of the P input. Comparative examination of P and N mass balances showed that most (85%) of the P input to VB accumulates in the sediments. Despite the hypolimnetic anoxia that VB exhibits from March to October, net P accumulation in the sediments is normally observed. Our results confirm that although VB behaves as a warm monomictic water body, its mean hypolimnetic temperature increases throughout the stratification period. Nitrogen limitation was indicated by the dissolved inorganic nitrogen (DIN) to total dissolved P (DIN:TDP = 8.3, molar) ratio during stratification periods. We estimated that N2 fixation exceeded denitrification. This net fixation could double the N loading from rivers and sewage. Management recommendations include (a) gauging of river and sewage inputs to VB, (b) reduction of P input through treatment of sewage from VB town and (c) monitoring and regulating fertilizers and other nonpoint source inputs in the Amanalco watershed. Valle de Bravo reservoir is similar to other eutrophic tropical lakes and reservoirs that could also improve their water quality through these management practices.
Abundance and habitat use of juvenile sunfish among different macrophyte standsParis D. Collingsworth; Christopher C. KohlerLake and Reservoir Management1040-23810743-8141261201035 - 42Abundance and habitat use of juvenile sunfish among different macrophyte stands Collingsworth, PD and Kohler, CC. 2010. Abundance and habitat use of juvenile sunfish among different macrophyte stands. Lake Reserv. Manage. 26:35-42. Juvenile Lepomis sunfish (< 75 mm total length, TL) density, plant stem density and invertebrate density were compared in the 3 most common habitats in the littoral zone of Cedar Lake, a Midwestern North American reservoir: nonvegetated areas, stands of the exotic macrophyte Eurasian watermilfoil (Myriophyllum spicatum) and stands of American pondweed (Potomogeton nodosus). Eurasian watermilfoil stands consistently had significantly higher stem density and invertebrate density than American pondweed stands. Juvenile sunfish densities were significantly higher in vegetated habitats than nonvegetated areas, but no significant differences were observed between the 2 vegetated habitats. Juvenile sunfish densities were initially higher in American pondweed stands than Eurasian watermilfoil stands, but fish density in American pondweed stands declined dramatically as water levels fell in autumn. Juvenile sunfish size structure was related to habitat type, with the smallest fish associated with Eurasian watermilfoil (38.2 mm TL), intermediate fish associated with American pondweed (43.1 mm TL), and the largest fish associated with nonvegetated habitats (51.2 mm TL). We suggest resource agencies should focus vegetation management efforts on eradicating Eurasian watermilfoil stands to provide foraging access for largemouth bass to improve their growth rate and reduce stunting of sunfish. However, management agencies must recognize that a healthy plant community below the depth of water level fluctuation may be the only source of cover for juvenile centrarchids during late summer in reservoirs prone to fluctuating water levels.
Influence of pumped-storage hydroelectric plant operation on a shallow polymictic lake: Predictions from 3-D hydrodynamic modelingMichael A. AndersonLake and Reservoir Management1040-23810743-814126120101-13Influence of pumped-storage hydroelectric plant operation on a shallow polymictic lake: Predictions from 3-D hydrodynamic modeling Pumped-storage hydroelectric plants play important roles in electrical supply grids by providing electricity during periods of peak demand, storing renewable energy and controlling supply frequency. The pumping of water from a lower lake or reservoir to an upper impoundment and the return of that water during power generation can strongly affect the properties of pumped-storage reservoirs, however. For example, plant operation has been found to delay, weaken or eliminate thermal stratification, resuspend bottom sediments and entrain organisms. The aim of this study was to better understand the impacts of a proposed pumped-storage facility on stratification, mixing and sediment resuspension in Lake Elsinore, a shallow, polymictic lake in southern California. Three-dimensional hydrodynamic simulations were conducted using the Environmental Fluid Dynamics Code (EFDC). Model simulations demonstrated regular variations in the lake surface elevation of 0.24-0.5 m associated with pumping and generation, although a large shore-mounted intake structure resulted in quite low velocities near the intake (< 6 cm/s), bottom shear values below the assumed critical threshold for resuspension (< 0.1 N/m2), and limited overall effect on stratification and mixing in the lake. Entrainment of larval fish and other planktonic organisms remains a concern, however.
Testing a methodology for assessing plant communities in temperate inland lakesAlison Mikulyuk; Jennifer Hauxwell; Paul Rasmussen; Susan Knight; Kelly I. Wagner; Michelle E. Nault; Daryl RidgelyLake and Reservoir Management1040-23810743-8141261201054 - 62Testing a methodology for assessing plant communities in temperate inland lakes We outline and test an aquatic plant sampling methodology designed to track changes in and make comparisons among lake plant communities over time. The method employs a systematic grid-based point-intercept sampling design with sampling resolution adjusted based on littoral area and lake shape. We applied this method in 72 Wisconsin lakes ranging from 6.5-245 ha in size, recording species presence-absence and depth at approximately 20,000 unique sample points. To assess how reductions in sampling effort might affect data quality, we used Monte Carlo simulations (100 iterations at each of 9 levels of sampling intensity) to reduce total lake sample points by 10% through 90% using a stratified random selection approach. Species accumulation curves were fit using the Michaelis-Menten 2-parameter formula for a hyperbola, and the predicted asymptote was similar to observed species richness. In a subset of lakes, oversampling (200% effort) did not yield significant increases in species richness. However, even a modest reduction (10-20%) in sampling effort affected species richness, while frequencies of occurrence of dominant species and estimations of percent littoral area and maximum depth of plant growth were less sensitive to sampling effort. In addition, we provide results of a power analysis for detecting changes in plant communities over time. Future applications of this protocol will provide information suitable for in-lake management and for assessing patterns in aquatic plant communities state-wide related to geographic region, hydrological characteristics, land use, invasive species and climate.
Assessing variability in total phosphorus measurements in Ontario lakesBev J. Clark; Andrew M. Paterson; Adam Jeziorski; Susan KelseyLake and Reservoir Management1040-23810743-8141261201063 - 72Assessing variability in total phosphorus measurements in Ontario lakes In most Ontario lakes, phosphorus is present in trace quantities, making the precise measurement of concentrations difficult. The considerable variation that results in many datasets can be attributed to imprecise analysis. Even with precise analysis, substantial variation in ice-free whole-lake, mean mixed layer, and spring turnover total phosphorus (TP) concentrations often remain, both between years and within a given year. Lake managers have adopted many strategies to address these issues. Whole-lake TP concentrations expressed as ice-free season means are difficult to derive because they require the collection of numerous, volume-weighted samples often from multiple lake layers. As a result, spring turnover or ice-free-mean, mixed layer TP concentrations are often used to characterize the trophic status of a lake or to describe the nutrients available for primary production. These different phosphorus characterizations will vary between years, leading many lake managers to use long-term (multiple year) means to describe trophic status. The ability to interpret natural variation or trends in these data can be reduced by any bias introduced through sample collection and storage (container) methods or as a result of sample contamination by zooplankton, which can produce high sample TP concentrations. Much variability can be reduced through precise analysis, and most sources of error can be eliminated by sampling directly into the same borosilicate glass tubes used to digest samples prior to analysis and by coarse filtering water samples in situ to 80 μ m to eliminate large zooplankton. We demonstrated the importance of collecting precise TP data and presented the variation associated with 25 years of TP measurements in Ontario, Precambrian Shield lakes. We also demonstrated various sample collection strategies that can be used to characterize the nutrient status of lakes and explained how the interpretation of these can be affected by variability in the results.
Common carp (Cyprinus carpio), sport fishes, and water quality: Ecological thresholds in agriculturally eutrophic lakesZachary J. Jackson; Michael C. Quist; John A. Downing; Joseph G. LarscheidLake and Reservoir Management1040-23810743-8141261201014 - 22Common carp (Cyprinus carpio), sport fishes, and water quality: Ecological thresholds in agriculturally eutrophic lakes We examined fish populations, limnological conditions, lake basin morphology and watershed characteristics to evaluate patterns in population characteristics of ecologically important fish species in relation to environmental conditions in agriculturally eutrophic lake systems. Fish populations and environmental characteristics were sampled from 129 Iowa lakes using standard techniques from 2001-2006. Lakes with high catch rates of common carp (Cyprinus carpio) had high nutrient concentrations, high phytoplankton biomass and low water transparency. In addition, lakes with high catch rates of common carp had low catch rates of important sport fishes including bluegill (Lepomis macrochirus), largemouth bass (Micropterus salmoides), black crappie (Pomoxis nigromaculatus) and white crappie (P. annularis). The relationship between common carp and sport fishes appeared to function as an ecological threshold. Specifically, when common carp catch rates were > 2 kilograms per fyke net night, catch rates of sport fish were always low and water quality in the study lakes was poor. Shallow systems (natural lakes, oxbows) had higher densities of common carp compared to deeper systems (impoundments, surface mines), thereby suggesting that shallow lakes are most sensitive to the effects of common carp and that restoration efforts incorporating biomanipulation of common carp will likely be most successful in shallow systems.
A retrospective analysis of suspended solids deposition in Onondaga Lake, New York: Composition, temporal patterns, and driversCraig A. Hurteau; David A. Matthews; Steven W. EfflerLake and Reservoir Management1040-23810743-8141261201043 - 53A retrospective analysis of suspended solids deposition in Onondaga Lake, New York: Composition, temporal patterns, and drivers Hurteau CA, Matthews DA, Effler SW. 2010. A retrospective analysis of suspended solids deposition in Onondaga Lake, New York: Composition, temporal patterns, and drivers. Lake Reserv. Manage. 26:43-53. Long-term and seasonal temporal patterns in the deposition of total (TSS), fixed (FSS) and volatile suspended solids (VSS) were documented for eutrophic Ca2 +-rich Onondaga Lake, New York, for the 1980-2008 interval. Weekly collections were made from sediment traps deployed below the thermocline from April to October in the deepest area of the lake (19.5 m). Downward fluxes of TSS (DFTSS), FSS (DFFSS) and VSS (DFVSS) decreased 42, 38, and 41%, respectively, following closure of a soda ash facility in 1986 that discharged ionic waste to the lake. The DFTSS decreased 47% from 2007 to 2008, driven mostly by lower CaCO3 deposition. Sediment accumulation rates derived from dry weight deposition were estimated to decrease from 0.8 cm/yr during 1980-1986 to 0.4 cm/yr during 1987-2007 to 0.2 cm/yr in 2008. On average, DFCaCO3 accounted for 83% of DFFSS and 69% of DFTSS. The event-like character observed for DFFSS was attributed to variations in CaCO3 precipitation, probably driven by variations in temperature, pH and the availability of nucleation sites. The DFVSS decreased 56% from 2.5 g/m2 · d to 1.1 g/m2 · d over the 1989 to 2008 interval. Decreased phosphorus loading from a municipal wastewater treatment facility explained 67% of the interannual variations in DFVSS. Weekly variations in the DFVSS were generally correlated with chlorophyll levels in the upper waters, and maximum values were observed during major phytoplankton blooms. Seasonal minima of DFVSS and DFFSS occurred during clear water phases, associated with Daphnia grazing, which were observed annually from 1987 to 2002, and again in 2008. Changes in primary production and lake chemistry could have significant effects on the burial of contaminants and microbial metabolism in the sediments.
Phosphorus balance of Lake Tiefwarensee during and after restoration by hypolimnetic treatment with aluminum and calcium saltsGerlinde Wauer; Thomas Gonsiorczyk; Michael Hupfer; Rainer KoschelLake and Reservoir Management1040-23810743-81412542009 377 - 388Phosphorus balance of Lake Tiefwarensee during and after restoration by hypolimnetic treatment with aluminum and calcium salts Between 2001 and 2005, the recovery of Lake Tiefwarensee from eutrophic to mesotrophic state was successfully accelerated by the stepwise hypolimnetic addition of 137 g aluminum and 154 g calcium per square meter of profundal sediment. In response to the treatment, an 8-cm sediment cover was formed, which almost completely suppressed the phosphorus (P) release from the sediments, and is still present. The spatial variability of the sediments was analyzed at eight sampling points at different lake depths. With increasing lake depth, soluble reactive phosphorus decreased in the pore water, whereas the total phosphorus (TP) increased in treated sediment. Total P in the upper sediment layer (0-10 cm) increased by about 3 tons during the treatment period, consistent with the simultaneous decrease in the water from 0.223 mg/L in 1998 to 0.013 mg/L in 2005 (annual mean values for the whole water body). After initial settling, the drastic TP decrease in the water column can be attributed to an increase in the sediment P-binding capacity, which is related to a decrease of the mobile P pool (NH4Cl-TP) and a strong increase in the Al:P ratio in sediment. In the 3 years after completion of the treatment, the lake TP concentration was well described by the Vollenweider model, indicating that a sustainable state of nutrient equilibrium was achieved.
Ecological classification of a set of Mediterranean reservoirs applying the EU Water Framework Directive: A reasonable compromise between science and managementE. Navarro; L. Caputo; R. Marcé; J. Carol; L. Benejam; E. García-Berthou; J. ArmengolLake and Reservoir Management1040-23810743-81412542009 364 - 376Ecological classification of a set of Mediterranean reservoirs applying the EU Water Framework Directive: A reasonable compromise between science and management The Water Framework Directive EU2000/60/EC (WFD) was implemented for reservoirs at a regional scale (northeastern Spain). Twenty-one reservoirs were monitored quarterly over the course of a year. Using principal component analysis, the reservoirs were classified into types according to their geological and morphometric features. The Ecological Quality (EQ) of the reservoirs was assessed by integrating values of total chlorophyll a, cyanophyta chlorophyll a concentration, fish metrics, Secchi depth, averaged hypolimnetic oxygen concentration and total phosphorus. For each reservoir type, a reference condition of quality was selected. When possible, this reference was the reservoir displaying the best EQ; otherwise expert judgment was used. To allow comparison of quality among reservoirs belonging to different types, thus identifying intrinsic differences, an Ecological Quality Ratio (EQR) was calculated by dividing the EQ value of each reservoir by that of its reference. According to EQR, the majority of the reservoirs accomplished the quality criteria of the WFD. This study identified a number of useful indicators for EQ assessment. Moreover, because the references were chosen among similar reservoirs, low EQR values are indicative of specific problems, such as untreated or wastewater spills or droughts. The results also demonstrate that expert judgment is a reasonable compromise when the low number of water bodies available for the study prevents statistical approaches.
Newman Lake restoration: A case study. Part I. Chemical and biological responses to phosphorus controlBarry C. Moore; David ChristensenLake and Reservoir Management1040-23810743-81412542009 337 - 350Newman Lake restoration: A case study. Part I. Chemical and biological responses to phosphorus control In the late 1960s and early 1970s, summer and fall blooms of cyanobacteria began to occur in Newman Lake, Washington (zavg: 5.6 m, zmax: 9.0 m); through the next decade, these blooms intensified and became an annual occurrence. Community efforts in the mid-1980s sparked a Restoration Feasibility assessment of the lake and watershed that indicated total annual gross phosphorus loading of at least 3000 kg, with a major portion (∼83%) attributable to internal recycling associated with summer hypolimnetic oxygen depletion. Implementation activities began September 1989, with watershed controls and a whole-lake alum treatment, followed in 1992 by installation of a Speece cone for hypolimnetic oxygenation and in 1997 by addition of a dual-port, microfloc alum injection system. Average summer volume-weighted total phosphorus has declined from prerestoration levels exceeding 50 μg-P/L to an average of 21 μg-P/L over the past 7 years (15-28 μg-P/L). Most notably, peak annual biovolumes of cyanobacteria and their representation within the phytoplankton community have decreased substantially, with increased prevalence of diatoms, green and golden-brown algae. A clearwater phase following spring blooms of diatom and/or golden-brown algae has occurred during those last 7 years, although this phenomenon was observed in the prior three decades. Overall, the restoration has been a success, and lake response to nutrient reduction at Newman Lake is consistent with worldwide observations that emphasize the need for long-term perspectives and commitment in lake restoration and management. Continuation of internal load controls and increased emphasis on external nutrient abatement will be necessary to continue the positive water quality trends despite future development increases and land use changes.
Newman Lake restoration: A case study. Part II. Microfloc alum injectionBarry C. Moore; David Christensen; Ann C. RichterLake and Reservoir Management1040-23810743-81412542009 351 - 363Newman Lake restoration: A case study. Part II. Microfloc alum injection Microfloc alum injection, in contrast to whole-lake alum treatments, is a relatively new technique for alum delivery that has been implemented in a relatively small number of lakes and reservoirs. Microfloc alum injection is primarily designed to precipitate phosphorus in the water column using low doses applied on a continuous or intermittent basis. The technique employs diffusers to create ultra-small aluminum hydroxide particles with lower settling velocities and longer residence times, compared to whole lake treatments, to strip dissolved phosphorus from the water column. Because relatively few microfloc systems have been deployed, a brief review of their characteristics and performance is provided. In Newman Lake, Washington, a microfloc alum injection system has been in use since spring 1997. We tested microfloc residence times using in situ enclosures; residence time was determined to be at least 10 days, supporting the underlying concept. In the lake itself, turnover events prior to alum injection consistently produced higher algae growth with accompanying lower Secchi transparency. Since alum injection, post-turnover Secchi depths have all improved. In 18 years with 32 monitored turnover events, this relatively robust dataset consistently indicates the short-term ability of microfloc to improve transparency through algae reduction. Volume-weighted total phosphorus concentrations also have generally declined following alum injection. Adverse biological impacts were not observed in either enclosures or the lake. In the enclosure studies, total zooplankton and cladoceran densities and biomass in treatments were not significantly different from controls. Further applications and study of this promising technology are warranted.
Phosphorus forms in urban and agricultural runoff: Implications for management of Danish Lake NordborgSara Egemose; Henning S. JensenLake and Reservoir Management1040-23810743-81412542009 410 - 418Phosphorus forms in urban and agricultural runoff: Implications for management of Danish Lake Nordborg The catchment of eutrophic Lake Nordborg, Denmark, consists of 25% urban areas with separate sewer systems and 63% agricultural areas with clayey soil and grain crops. Diffuse runoff is the only external phosphorus (P) source (∼ 550 kg/yr), but the lake suffers from high internal loading (∼ 1300 kg/yr). In-lake aluminum treatment is suggested if external P-loading can be brought down by ∼ 30% to an annual average inlet concentration of < 0.100 mg/L. We examined the share and bioavailability of particulate P (PP) in 14 tributaries during a winter season to evaluate if the reduction in bioavailable P-load can be obtained by construction of precipitation/retention ponds in major inlets. One-third of the P-load occurred as PP, independent of catchment type. For urban runoff, 62% of PP was surface adsorbed P, iron-bound P, and extractable organic P, all of which may be considered bioavailable. The corresponding value for agricultural tributaries was 76%. For both types of catchments more than 70% of total P (PP and dissolved P) was bioavailable, but total concentrations were much higher (0.174 ± 0.032 mg/L) in agricultural runoff than in urban runoff (0.082 ± 0.019 mg/L). Measurements of PP settling velocity revealed that ∼ 30% settled slower than 1 cm/h whereas ∼ 50% settled faster than 1 m/h. Therefore, water retention time in precipitation ponds to Lake Nordborg should exceed 8 h to reach the target reduction in P-load. Focus should be on the agricultural catchment that contributes 140 kg to PP load, rather than the urban catchment that only contributes 48 kg.
Assessing internal phosphorus load - Problems to be solvedGertrud K. NürnbergLake and Reservoir Management1040-23810743-81412542009 419 - 432Assessing internal phosphorus load - Problems to be solved Internal loading as phosphorus (P) released from anoxic sediment surfaces often represents the main summer P load to lakes and reservoirs and can have an immense effect on their water quality. Many difficulties in internal load assessment exist, however, including ignoring internal load altogether, ambiguity about the origin of sediment released P and inexact definitions. Most of these problems are due to the difficulty in distinguishing internal from external P sources, which is particularly challenging in polymictic lakes. To prevent misconceptions and facilitate its evaluation, internal load in stratified and polymictic lakes should be expressed in a similar way to external loads: as annual, gross and areal load of total phosphorus (TP). Possible approaches to internal load quantification are: in situ determination from hypolimnetic P increases, mass balance approaches, and estimates from anoxic active area and P release. Further suggestions to facilitate the study of internal loading include: (a) the differentiation between polymictic and stratified lakes, sections of lakes, and time periods when evaluating indicators and impact of internal load; (b) the separation of internal load (upward flux) from sedimentation (downward flux) of external and internal loads, and (c) the consideration of the downward flux of both external (Lext, mg/m2/yr) and internal (Lint, mg/m2/yr) loads by a retention model (Rsed) when predicting lake TP averages in a mass balance model of the form (qs = annual areal water load in m/yr):
Should nitrogen be reduced to manage eutrophication if it is growth limiting? Evidence from Moses LakeEugene B. WelchLake and Reservoir Management1040-23810743-81412542009 401 - 409Should nitrogen be reduced to manage eutrophication if it is growth limiting? Evidence from Moses Lake The recovery of Moses Lake from hypereutrophy to mesotrophy over a 25-year period resulted from the addition of large quantities of low nitrogen (N) and phosphorus (P) dilution water and a change in irrigation practices. Throughout the recovery, the in-lake ratio of nitrate-N to soluble reactive P (SRP) remained well below the Redfield ratio, indicating short-term N limitation. Nevertheless, the disproportionately greater reduction in inflow P than N, relative to the Redfield ratio, caused the long-term reduction of total P (TP), SRP and chlorophyll. Lake TN:TP ratios consistently remained slightly above the Redfield ratio, apparently through N fixation, despite continued N limitation. Cyanobacteria (primarily Aphanizomenon) dominated the plankton algae during the recovery period until the lake became mesotrophic and calculated net internal loading of P was undetectable. These results demonstrate that usually inflow P, not N, should be reduced to effect long-term recovery of eutrophic lakes, despite observed short-term limitation by N.
Nutrient fluxes across reaches and impoundments in two southeastern Michigan watershedsNathan S. Bosch; Thomas H. Johengen; J. David Allan; George W. KlingLake and Reservoir Management1040-23810743-81412542009 389 - 400Nutrient fluxes across reaches and impoundments in two southeastern Michigan watersheds River systems with impoundments are expected to experience greater nutrient removal as a consequence of enhanced nitrogen (N) loss by denitrification, settling and burial of phosphorus (P), and longer residence times of water relative to a free-flowing river. We evaluated the magnitude of N and P removal across stream reaches and impoundments, including annual and seasonal trends, in two southeastern Michigan rivers that differ in their degree of impoundment and watershed land use patterns. All nutrient fraction concentrations remained statistically unchanged across stream reaches of 2-3 km in length, but dissolved oxygen and pH increased. Impoundment outlets exhibited increases in water temperature and decreases in conductivity, TP, TN, TDP, SRP, TDN, and NO3-N relative to inflowing water. A nutrient load mass balance showed that two connected impoundments removed 18 and 32% of the annual river loads of TN and TP, respectively. Removal rates were seasonably variable, with TP removal most pronounced during winter months when the impoundment received episodic high P loads. Conversely, TN removal was greatest during summer and autumn months when impoundments were stratified and water temperatures were elevated. Strong seasonal differences in N and P transport through the impoundments demonstrated the capacity of impoundments to dramatically alter the timing and stoichiometry of downstream nutrient export. These seasonal differences also highlight the need to consider the entire annual cycle when estimating surface water nutrient dynamics or designing management plans for nutrient abatement.
Managing the lakes of the Rotorua District, New ZealandNoel Burns; John McIntosh; Paul ScholesLake and Reservoir Management1040-23810743-81412532009 284 - 296Managing the lakes of the Rotorua District, New Zealand In 2005, Burns, McIntosh and Scholes described strategies to manage the Rotorua Lakes using lake monitoring together with designated baseline Trophic Level Index values established for each lake. Continued monitoring has revealed that 9 of the 12 Rotorua Lakes have Trophic Level Index values in excess of their baseline values. Action Plans have been drawn up for the remediation of these damaged lakes that specify the excess nutrient loading to each lake and propose actions for the decrease of these loadings. Nutrient loading to various lakes has been decreased by upgrading waste treatment facilities, dosing tributary streams with alum, diverting an enriched tributary flow directly into the outflow channel of a lake, precipitating in-lake phosphorus with Phoslockâ„¢ and zeolite additions, and removal of macrophyte biomass from a lake and planting an artificial wetland at the entry point of a tributary to a lake. Where data are available, the results of these actions are explored. The similarities between the management system for the Rotorua lakes with the management systems used for two American and European lakes are described.
Reduced river phosphorus following implementation of a lawn fertilizer ordinanceJohn T. Lehman; Douglas W. Bell; Kahli E. McDonaldLake and Reservoir Management1040-23810743-81412532009 307 - 312Reduced river phosphorus following implementation of a lawn fertilizer ordinance Statistical comparisons of 2008 surface water quality data with a historical data set at weekly and subweekly resolution revealed statistically significant reductions in total phosphorus (TP) and a trend of reduction in dissolved phosphorus following implementation of a municipal ordinance limiting the application of lawn fertilizers containing phosphorus. No reductions were seen at an upstream control river site not affected by the ordinance. Nontarget analytes including nitrate, silica and colored dissolved organic matter did not change systematically as did P. The data were analyzed in the context of a statistical model that characterized historical temporal variability and predicted the sampling effort needed to detect changes of specified magnitude. Expected changes of about 25% in monthly mean value were predicted to require weekly samples during the summer for only 1 or 2 years for TP; statistically significant reductions measured after 1 year averaged 28%, or about 5 kg P/day. The lawn fertilizer ordinance was only one component of broader efforts to reduce nonpoint source loading of P, however, so the magnitude of its role in the measured changes remains uncertain.
Phosphorus reduction by dilution and shift in fish species in Moses Lake, WAEugene B. WelchLake and Reservoir Management1040-23810743-81412532009 276 - 283Phosphorus reduction by dilution and shift in fish species in Moses Lake, WA Water quality over most of the area of Moses Lake improved greatly over a 25-year period (1977-2001) due largely to the addition of large quantities of low-nutrient Columbia River water as well as changed irrigation practices and diversion of wastewater. The oligotrophication of Moses Lake from hypereutrophy to borderline mesotrophy was accompanied by a marked shift in fish populations, determined by creel census and biological surveys that included electrofishing and gill netting. The catch fraction of panfish (crappie and bluegills) decreased markedly; largemouth bass decreased to a lesser extent, while smallmouth bass, walleye and brown bullhead increased several-fold. These population shifts are consistent with observations elsewhere in response to oligotrophication and piscivory.
Partitioning phosphorus concentrations and loads in tributaries of a recovering urban lakeSteven W. Effler; Anthony R. Prestigiacomo; David A. Matthews; Edward M. Michalenko; Donald J. HughesLake and Reservoir Management1040-23810743-81412532009 225 - 239Partitioning phosphorus concentrations and loads in tributaries of a recovering urban lake The partitioning of phosphorus (P) loading to culturally eutrophic lakes according to sources is fundamental information to guide rehabilitation programs and support mathematical models. Patterns of concentrations and loading rates of forms of P are documented for the major tributaries of Onondaga Lake, New York, United States, an urban lake that has recently demonstrated marked recovery from extreme cultural eutrophy as a result of decreased P loading from a domestic wastewater treatment plant (WWTP). This analysis is based on long-term (19 yr) biweekly monitoring of total, dissolved, and soluble reactive forms of P at the mouths of the three largest tributaries, and shorter-term higher frequency monitoring of one of the streams at two sites to resolve rural versus urban contributions. Signatures of anthropogenic sources were identified, including: (1) combined sewer overflows, (2) leaky sewers or other dry weather discharges, and (3) hydrogeologic sediment sources. On an annual average basis, the prevailing tributary and WWTP contributions to the total P load are approximately 70 and 30%, respectively. However, in terms of effective P loading, that which can be used to support primary production during the critical summer months, the tributaries contributed substantially less (∼35%) of the P load. Under the prevailing WWTP loading rate, reductions in tributary loading from aggressive tributary loading management efforts (e.g., 20-30% decrease) would not be expected to yield conspicuous improvements in related features of lake water quality. However, noteworthy improvements are a reasonable expectation from such tributary management efforts following the mandated further reductions in WWTP loading.
Blue-green algal toxin (microcystin) levels in Minnesota lakesMatt Lindon; Steven HeiskaryLake and Reservoir Management1040-23810743-81412532009 240 - 252Blue-green algal toxin (microcystin) levels in Minnesota lakes Increased interest in blue-green algal toxins in recent years has led to increased monitoring to assess occurrence and levels of toxins in Minnesota lakes. Microcystin (MC), a hepatotoxin, is one of the primary toxins studied in Minnesota and elsewhere in North America. The Minnesota Pollution Control Agency has measured MC in numerous lakes across Minnesota as a part of three separate efforts: (1) A targeted survey in 2006 to assess MC levels in 12 eutrophic lakes in two south central Minnesota counties; (2) A stratified-random survey of 50 lakes in Minnesota as a part of the National Lake Assessment Project; and (3) Incident-based samples from various lakes during 2004-2007 with reports of severe nuisance algal blooms, potential for human health risk and/or documented dog deaths as a result of algal toxins. This investigation focuses primarily on the 2006 study and linkages between MC and other chemical, physical and biological measures. Of 133 MC samples, 94% were above the Method Detection Limit (MDL = 0.15 ug/L). Based on World Health Organization guidelines, 80% of all MC samples ranked in the “low risk” category (<10 μg/L), 8% as “moderate risk” (>10-20 μg/L), 11% as “high risk” (20-2000 μg/L), with an overall maximum of 8400 μg/L. Microcystin exhibited significant positive correlations (Rs) with pH and chlorophyll-a and significant negative correlations with alkalinity and Secchi depth. Data from the other two efforts place the 2006 results in perspective and provide a comprehensive representation of MC concentrations in Minnesota lakes and an improved basis for communicating risk to the public.
Microcystin in Missouri reservoirsJennifer L. Graham; John R. JonesLake and Reservoir Management1040-23810743-81412532009 253 - 263Microcystin in Missouri reservoirs During summers (May-Aug) 2004-2006, 177 Missouri reservoirs were sampled monthly at open pelagic locations to assess regional patterns in microcystin concentration, frequency of occurrence over successive summer seasons and relations with environmental factors. Microcystin was detected in 58% of Missouri reservoirs and 23% of samples (n = 1402). Total microcystin concentrations, measured by enzyme-linked immunosorbent assay, ranged from ≤ 0.1 to 21 μg/L. Concentrations ≥ 1 μg/L were detected in 10% of reservoirs and exceeded the human health concern limit of 20 μg/L once in a single sample. Microcystin occurred throughout summer, with maximum concentrations in individual reservoirs observed in each month. Occurrence was consistent across years, with about one-half of Missouri reservoirs having detectable microcystin each summer. Eleven reservoirs with microcystin maxima ≥1 μg/L were sampled multiple seasons; of these, 8 had detectable microcystin each summer, which indicates that short-term surveys can identify water bodies with the greatest potential for toxin production. Eutrophic reservoirs in northern Missouri had the greatest microcystin occurrence and concentrations. Reservoirs with detectable microcystin had significantly (p < 0.01) greater nutrient and chlorophyll values and significantly shallower Secchi depths than reservoirs without detection. All correlations, however, had r-values ≤ 0.35, and bivariate plots indicated nonlinear trends. Cylindrospermopsin was measured by enzyme-linked immunosorbent assay in 36 reservoirs once in late summer 2006; 14% had small detectable levels (total concentrations < 1 μg/L). This is the first report of cylindrospermopsin in Missouri.
Survey of toxic algal (microcystin) distribution in Florida lakesD. L. Bigham; M. V. Hoyer; D. E. Canfield Jr.Lake and Reservoir Management1040-23810743-81412532009 264 - 275Survey of toxic algal (microcystin) distribution in Florida lakes A survey of microcystin in 187 Florida lakes was completed from Jan to Dec 2006. Annual average microcystin concentrations of the 187 Florida lakes ranged from nondetectable (< 0.1 μ g/L) to 12 μ g/L, with concentrations in individual water samples (N = 862) ranging from nondetectable to 32 μ g/L. Only 7% of all the individual samples exceeded the World Health Organization (WHO) drinking guidance value of 1 μ g/L. Three individual water samples collected from two lakes (0.3%) exceeded the WHO recreational guidance value of 20 μ g/L. Using chlorophyll concentrations and Secchi depth measurements, tables were constructed to predict the probability that microcystin concentrations exceeded the WHO guidance values in Florida lakes. Additionally, six hypereutrophic lakes (Harris Chain of Lakes, Lake County, FL) were studied from Sep 2006 to Aug 2007 and 40% of the samples exceeded 1 μ g/L but none exceeded 20 μ g/L. This study also provides baseline information and relations between trophic status, seasonality, water chemistry and microcystin concentrations in Florida lakes.
A Review of “Environmental Best Management Practices for Aquaculture”Craig S. Tucker and John A. F. Hargreaves, eds. First edition 2008. Blackwell Publishing. ISBN-13: 978-0-8138-2027-9.Lake and Reservoir Management1040-23810743-81412532009336A Review of “Environmental Best Management Practices for Aquaculture”
Factors contributing to cucumber odor in a northern USA reservoirLauren A. Schroeder; Scott C. Martin; Amulya PoudelLake and Reservoir Management1040-23810743-81412532009 323 - 335Factors contributing to cucumber odor in a northern USA reservoir Episodic occurrences of cucumber odor caused by the alga Synura petersenii in Meander Creek Reservoir (MCR), northeastern Ohio, USA, are partly attributed to increased water transparency resulting from decreased phosphorus and suspended solids loading from the watershed. The first documented occurrence of nuisance odor levels was in 1984, 52 years after the reservoir was filled. This indicates that previous environmental factors constraining the growth of S. petersenii have been relaxed, probably from changes in the physical-chemical environment in the reservoir caused by changes in land use in the catchment. Reduction in farming since 1950, and diversion of sewage around the reservoir in 1977, reduced suspended solids and total phosphorus loading into the reservoir during the time that the cucumber odors occurred. These observations support the hypothesis that increased transparency of the reservoir, resulting from decreased sediment loading and reduced productivity, has permitted the occasional occurrence of nuisance densities of S. petersenii. Based on available data, pH, iron, and silica do not appear to be key factors regulating growth of S. petersenii in MCR. The transition to lower turbidity and total phosphorus concentrations from catchment restoration actions may increases the risk of S. petersenii blooms and cucumber odor episodes. While the overall benefits of cleaner raw water for water supply may outweigh this risk, it is desirable to understand the factors that promote nuisance growths and take actions to control them.
Assessing hypolimnetic oxygen concentrations in Canadian Shield lakes: Deriving management benchmarks using two methodsA. M. Paterson; R. Quinlan; B. J. Clark; J. P. SmolLake and Reservoir Management1040-23810743-81412532009 313 - 322Assessing hypolimnetic oxygen concentrations in Canadian Shield lakes: Deriving management benchmarks using two methods The ability to predict hypolimnetic dissolved oxygen concentrations in lakes and to track changes in concentrations over time in response to known environmental stressors is critical for effective lake management. The background concentrations of deepwater oxygen, in particular, provide important management benchmarks for assessing the impact of current and future shoreline residential development on water quality. Background can be defined as the conditions that exist in the absence of, or prior to, human influence. We compare 2 models commonly used to predict end-of-summer, volume-weighted hypolimnetic oxygen (VWHO) concentrations in Canadian Shield lakes. The paleoecological and empirical models are evaluated in their ability to predict present-day VWHO concentrations, and then compared in their predictions of background VWHO concentrations and in predictions of changes in VWHO from background to present-day conditions. The predictive power of the 59-lake paleoecological model (jackknifed r2 = 0.51, RMSEP = 2.18 mg/L) is comparable to other models that have used chironomids to predict the degree of hypolimnetic anoxia in lakes but is lower than that produced by the empirical modelling approach (r2 = 0.87, SE = 1.04 mg/L). However, this discrepancy may be offset by the enhanced realism of the paleoecological model, including its ability to predict declines in VWHO over time. The combined use of the paleoecological and empirical modelling approaches may allow lake managers to examine changes in deepwater oxygen concentrations in response to a single “targeted” stressor (e.g., residential shoreline development) and to multiple environmental stressors (e.g., climate change, hydrological management).
Using numerical models and acoustic methods to predict reservoir sedimentationŞebnem Elçi; Aslı Bor; Anıl ÇalışkanLake and Reservoir Management1040-23810743-81412532009 297 - 306Using numerical models and acoustic methods to predict reservoir sedimentation This study draws on drainage basin hydrography, numerical modeling and geographic information system (GIS) techniques in concert with dual frequency echo sounder data to estimate sediment thickness when initial surveys are unavailable or inaccurate. Tahtali Reservoir (Turkey), which provides 40% of water supply to the city of Izmir, was selected as the study site. Deposition patterns within the whole lake were estimated with a 3-D hydrodynamic and sediment transport model applied to Tahtali Reservoir. The numerical model simulated lake response to wind forcing and inflows and/or outflows and was used to describe sediment deposition patterns resulting from the erosion of soils quantified by the implementation of Universal Soil Loss Equation (USLE) to the whole watershed. Surveying of the lake via dual frequency (28/200 kHz) echo sounder system revealed the current bathymetry, and sediment thickness was estimated from the difference of depths measured by the dual frequency sounder along surveyed transects. These results were compared to the modeled sedimentation thicknesses and to preliminary estimates of watershed sediment yield estimated by USLE. Results of this study can be used for further water quality studies and for long term management plans.
Trophic status of three large Missouri River reservoirsDavid W. Bolgrien; Jill V. Scharold; Ted R. Angradi; Tim D. Corry; E. William Schwieger; John R. KellyLake and Reservoir Management1040-23810743-81412522009 176 - 190Trophic status of three large Missouri River reservoirs Bolgrien, D.W., J.V. Scharold, T.R. Angradi, T.D. Corry, E.W. Schwieger and J.R. Kelly. 2009. Trophic status of three large Missouri River reservoirs. Lake Reserv. Manage. 25:176-190. Probability-based surveys conducted between 2001-2004 characterized the three large reservoirs of the Missouri River—Lake Oahe, Lake Sakakawea, and Fort Peck Lake—as mesotrophic to eutrophic, phosphorus (P) limited, and generally supporting cold water habitat (bottom waters <15°C and dissolved oxygen [DO] concentrations >5 mg/L) in midsummer. Riverine zones were shallower, warmer, more eutrophic, and had lower DO and higher suspended matter concentrations than lacustrine zones. Similar, although more variable, differences were found between bays and open-water areas. Between sampling years, water levels decreased in each reservoir. In the first year of sampling, area-weighted mean reservoir trophic status index based on chlorophyll (TSIchl) was about 37 in all three reservoirs. Sixty percent of Oahe and Sakakawea and 40% of Fort Peck had TSIchl> 50. Trophic status index based on Secchi depth (TSISD) averaged about 50 in each reservoir across years. Because mean TSIchl< TSISD, light attenuation was considered to be silt, not algae, dominated. Trophic status index based on total P (TSITP) and the ratio of N:P concentrations indicated that the reservoirs were very P limited. Mean bottom temperature and DO concentration in Oahe were unchanged between years at about 19°C and 7.5 mg/L, respectively. Bottom temperatures in Sakakawea increased (from 15°C to 21°C) and DO concentration decreased (from 7.3 mg/L to 6.0 mg/L) with lower water levels. In Fort Peck, bottom temperature remained about 18°C, but DO concentration fell from 7.23 mg/L to 4.96 mg/L. Results show that surveys successfully characterized important environmental conditions throughout these large reservoirs.
Water-level observations of Lake Weishan-Zhaoyang-Nanyang in China during 1814∼1902 ADJie FeiLake and Reservoir Management1040-23810743-81412522009 131 - 135Water-level observations of Lake Weishan-Zhaoyang-Nanyang in China during 1814∼1902 AD Fei, J. 2009. Water-level observations of Lake Weishan-Zhaoyang-Nanyang in China during 1814 ∼ 1902 AD. This article reports the evaluation and preliminary interpretation of the monthly water-level observations of Lake Weishan-Zhaoyang-Nanyang (WZN) in east China during 1814∼1902 AD. Observations were conducted by the government. According to the extant historical literature, the gaps in observations for this time period are 13.2%, 24.9%, and 24.5%, respectively, for the three parts of the lake: Weishan, Zhaoyang, and Nanyang. After a preliminary interpretation, we suggest that a correspondence exists between the high water-level years of Lake WZN and the flood years of the Yellow River during 1814∼1902 AD.
Development and application of a WASP model on a large Texas reservoir to assess eutrophication controlMark R. Ernst; Jennifer OwensLake and Reservoir Management1040-23810743-81412522009 136 - 148Development and application of a WASP model on a large Texas reservoir to assess eutrophication control Ernst, M.R. and J. Owens. 2009. Development and application of aWASP model on a large Texas reservoir to assess eutrophication control. The Tarrant Regional Water District developed and calibrated an 11-yr WASP-Eutro model for Cedar Creek Reservoir, a 13,350 ha (33,000 ac) drinking water supply and recreation reservoir located near Fort Worth, Texas, that is experiencing eutrophication. Cedar Creek was partitioned into 22 segments with up to three vertical segments in the main pool. Loading to the reservoir was divided into four categories: (1) watershed, (2) nine wastewater treatment plants (5.6 mgd), (3) atmospheric loading, and (4) internal NH4 and OPO4 sediment flux. Watershed loading was derived from a SWAT model of the 1007 mi2 watershed. Wastewater treatment plant loading was based on 1 yr of weekly plant nutrient and flow data. Atmospheric loading was estimated from periodic rain sampling adjacent to the reservoir. Internal flux was estimated from hypolimnetic accumulation during stratification. Calibration was judged by conformity of median observed and predicted water quality data and longitudinal profiles in the reservoir. Sensitivity analysis of these four loadings revealed that Chla and total phosphorus were most influenced by the watershed nonpoint source load. Internal flux was the next most influential load; form, timing and location of loading are more important than actual magnitude of this load. Estimates of the nonpoint source reduction necessary for a significant reduction in Chla were about 30%, while estimates of reductions in OPO4 flux to significantly reduce Chla were 75-100%. A combination of watershed and internal nutrient control are needed to control eutrophication in Cedar Creek Reservoir.
Factors affecting water willow establishment in a large reservoirParis D. Collingsworth; Ryan A. Oster; Christopher W. Hickey; Roy C. Heidinger; Christopher C. KohlerLake and Reservoir Management1040-23810743-81412522009 191 - 198Factors affecting water willow establishment in a large reservoir Collingsworth, P.D., R.A. Oster, C.W. Hickey, R.C. Heidinger and C.C. Kohler. 2009. Factors affecting water willow establishment in a large reservoir. Lake Reserv. Manage. 25:200-207. We evaluated the transplanting potential of an emergent macrophyte, water willow (Justicia americana), into Rend Lake, a large, relatively unvegetated reservoir in southern Illinois. We transplanted water willow over two years into sites varying in physical conditions and using four propagule types. Transplanting in 2001 was performed to compare the durability of root crowns, plugs, and stem fragments, as well as to measure the effect of open water versus backwater sites on water willow survival. Water willow was transplanted in 2002 to explore how different planting protocols, such as planting in different months, planting different propagule types, and shoreline slope affect water willow survival. We found that water willow transplanted early in the summer had better post-winter colony survival and vigor (stem density within colonies) than transplants conducted later in the summer (Kruskal-Wallis test; P = 0.017). Rooted propagules had significantly greater first-year colony survival and ultimately exhibited greater vigor in newly established colonies. Lastly, we found that shoreline slope had a significant influence on the vigor of colonies following winter dormancy but was not significantly related to first-year colony vigor. In the summer following their initial transplanting, established water willow colonies planted on shorelines with steeper slopes (>5°) produced more plants than those planted on shallower shorelines (Kruskal-Wallis test; P = 0.003). Water willow seems to have high potential as a transplant species for reservoir management and riparian zone enhancement.
Effect of aquatic macrophytes on the survival of Escherichia coli in a laboratory microcosmGregory Kleinheinz; Amy Coenan; Tabitha Zehms; Justine Preedit; Mary-Catherine Leewis; Donna Becker; Colleen McDermottLake and Reservoir Management1040-23810743-81412522009 149 - 154Effect of aquatic macrophytes on the survival of Escherichia coli in a laboratory microcosm Kleinheinz, G., A. Coenan, T. Zehms, J. Preedit, M.C. Leewis, D. Becker and C. McDermott. 2009. Effect of aquatic macrophytes on the survival of Escherichia coli in a laboratory microcosm. Recreational beaches are very important as engines for tourism revenue in many areas of Wisconsin, United States, and microbial contamination of beach water can be very costly. Escherichia coli (E. coli) is the indicator organisms used in the Great Lakes region of the United States for recreational water monitoring. The overall objective of this study was to determine if aquatic macrophytes (Sagittaria sp., Myriophyllum sp.) allow for prolonged E. coli survival in the environment by using a laboratory microcosm as a test system. This study tested whether E. coli survival was greater in lake water alone or in lake water containing a high density of macrophytes (HDM), a low density of macrophytes (LDM), or plastic plant material. Water and plant substrate samples were analyzed for E. coli concentrations. ANOVA analysis indicated a significant difference between all treatments (p < 0.001). The Scheffe test revealed a significant difference between E. coli concentrations in water in the HDM treatment and the plastic plants (p = 0.003) and the controls (lake water only; p < 0.001), as well as differences between the LDM treatments and the plastic plants (p < 0.001) and the controls (p < 0.001). Attachment of E. coli to the macrophytes was rapid and may contribute to the rapid decline of E. coli found in the microcosm water samples. The presence of aquatic macrophytes did not appear to provide growth factors or other substances that could prolong the survival of E. coli in water, but the plants may contribute to bacterial survival by providing a medium for bacterial attachment. To our knowledge this is the first study reporting on the effects of aquatic macrophytes on E coli concentrations in water.
Using structural equation modeling and expert elicitation to select nutrient criteria variables for south-central Florida lakesMelissa A. Kenney; George B. Arhonditsis; Linda C. Reiter; Matthew Barkley; Kenneth H. ReckhowLake and Reservoir Management1040-23810743-81412522009 119 - 130Using structural equation modeling and expert elicitation to select nutrient criteria variables for south-central Florida lakes Kenney, M.A., G.B. Arhonditsis, L.C. Reiter, M. Barkley, and K.H. Reckhow. 2009. Using structural equation modeling and expert elicitation to select nutrient criteria variables for south-central Florida lakes. To protect the nation's waterbodies from excessive impairments from pollution leading to eutrophication, the Clean Water Act requires states to establish water quality standards. These water quality standards are designed to protect the designated use, or water quality goal; however, they are indirectly measured and assessed using a water quality criterion. An alternative approach to develop nutrient criteria is the predictive approach (Reckhow et al. 2005), which determines the predictive variables by combining water quality data with assessments from multiple experts on the probability of designated use attainment using structural equation modeling (SEM). Our objective was to expand the predictive approach to include a region of waterbodies and to use multiple experts. To demonstrate these extensions, the approach was applied to lakes in south-central Florida using four experts to quantify attainment of a fish and wildlife designated use. Multiple models were built that related eutrophication processes to the designated use. Of the two plausible models, total phosphorus was the most predictive of the designated use followed by chlorophyll a. Using the model results, the risk of nonattainment of the designated use for these two predictive variables was calculated; to achieve high attainment (90% or more), total phosphorus should be < 0.015 mg/L and chlorophyll a < 5 μ g/L. This study provides vital extensions to the previous approach through its use of multiple experts and a region of lakes, making the approach applicable to other regions of waterbodies and conclusions useful to inform policy.
Shoreline stabilization using riprap breakwaters on a Midwestern reservoirJohn P. Severson; Jack R. Nawrot; Mike W. EichholzLake and Reservoir Management1040-23810743-81412522009 208 - 216Shoreline stabilization using riprap breakwaters on a Midwestern reservoir Severson, J.P., J.R. Nawrot and M.W. Eichholz. 2009. Shoreline stabilization using riprap breakwaters on a Midwestern reservoir. Lake Reserv. Manage. 25:208-216. Shoreline erosion causes shoreline habitat loss and degradation and contributes to sedimentation, a major impairment in many lakes throughout the United States. Various shoreline stabilization techniques have been employed, but many are unsuccessful under high wave stress, do not contribute to shoreline habitat, or are too expensive to install on a large scale. Extensive erosion and lack of shoreline habitat on Kinkaid Lake in southern Illinois prompted lake managers to design and install riprap breakwaters to protect the littoral zone and bank as well as enhance habitat. The offshore breakwaters were shown to decrease wave height and associated erosion, allowing banks to start stabilizing and the protected littoral zone to begin sequestering sediment. Terrestrial area inside the protected zones was regressed against age since protection, bank height, and distance from bank to produce a terrestrialization predictive model. Vegetation richness was much greater at protected sites than unprotected sites, and vegetation cover increased with age since protection. The riprap breakwaters were successful at bank stabilization and habitat enhancement and should therefore be considered for use where these attributes are desired.
Relative influence of lake age and watershed land use on trophic state and water quality of artificial lakes in KansasEdward CarneyLake and Reservoir Management1040-23810743-81412522009 199 - 207Relative influence of lake age and watershed land use on trophic state and water quality of artificial lakes in Kansas E. Carney. 2009. Relative influence of lake age and watershed land use on trophic state and water quality of artificial lakes in Kansas. Lake Reserv. Manage. 25:199-207. Eutrophication is an extensively documented concern for lake and reservoir management throughout the world. Eutrophication is also recognized as a naturally occurring process in both natural and artificial lakes, although it can be greatly augmented by human activities and is then referred to as “cultural eutrophication.” Unfortunately, natural process eutrophication is still sometimes used as a rationalization for not working toward the prevention or abatement of nutrient related pollution. Here, trophic state and other water quality data from a long-term (1975 to present) lake monitoring program were examined to determine the relative influences of watershed land use conditions and age in determining the trophic state conditions of artificial lakes in Kansas. The results indicate that age alone exerts very limited influence on eutrophication whereas watershed land use exerts an extreme, and often rapid, impact. Regardless of age, lakes within relatively unimpacted watersheds displayed trophic state conditions near regional reference conditions. Conversely, lakes within watersheds rich in human activities, regardless of water body age, tended toward greatly elevated trophic status. Eutrophication as a natural process is shown to be an invalid argument for ignoring excessive nutrient export from watersheds.
A Review of “Pollution of Lakes and Rivers: A Paleoenvironmental Perspective”John P. Smol. Second Edition. 2008. Blackwell Publishing. ISBN: 978-1-4051-5913-5. 383 pagesLake and Reservoir Management1040-23810743-81412522009224A Review of “Pollution of Lakes and Rivers: A Paleoenvironmental Perspective”
Quantitative evaluation of water-level effects on “regeneration safe-sites” for lakeshore plants in Lake Kasumigaura, JapanJun Nishihiro; Izumi WashitaniLake and Reservoir Management1040-23810743-81412522009 217 - 223Quantitative evaluation of water-level effects on “regeneration safe-sites” for lakeshore plants in Lake Kasumigaura, Japan Nishihiro, J. and I. Washitani. 2009. Quantitative evaluation of water-level effects on “regeneration safe-sites” for lakeshore plants in Lake Kasumigaura, Japan. Lake Reserv. Manage. 25:217-223. We evaluated the effects of water-level regime on the area of “regeneration safe-sites” for seed germination and initial establishment of seedlings of helophytes occurring in the emergent vegetation zone of Lake Kasumigaura, Japan. Based on the results of previous studies and an original experiment, potential regeneration safe-sites (PRS) for helophytes were defined as sites in which the ground surface was inundated for less than 3 consecutive days from 1 April to 15 May. We estimated and compared the areas of PRS both before and after the implementation of an artificial water-level regime in the mid-1970s. Comparisons were made using data on daily water levels during 1960-1969 and 1996-2005, topographic profiles of the lakeshore in 1967 and 2005, and areas of the emergent vegetation in 1972 and 1997. We estimated that the current area of PRS in the lake has been reduced to 24% of past levels. This reduction was accompanied by both a complete loss of a spring drawdown and a decrease in the area of emergent vegetation. The areas of PRS under various water management regimes indicated that a relatively slight lowering of the spring water level could cause a marked increase in the area of PRS (e.g., a 10-cm decrease in the managed target water level could result in a doubling of the area of PRS). Our results suggest a water-level management policy that includes a spring drawdown can be effective in the restoration of helophyte species diversity through the recovery of PRS.
Using stable isotopes and a multiple-source mixing model to evaluate fish dietary niches in a mesotrophic lakeDavid R. Christensen; Barry C. MooreLake and Reservoir Management1040-23810743-81412522009 167 - 175Using stable isotopes and a multiple-source mixing model to evaluate fish dietary niches in a mesotrophic lake Christensen, D.R. and B.C. Moore. 2009. Using stable isotopes and a multiple-source mixing model to evaluate fish dietary niches in a mesotrophic lake. Lake Reserv. Manage. 25:167-175. We used stable isotope analysis (SIA) of δ13C and δ15N and a multiple-source mixing model to evaluate dietary niches within the Twin Lakes, Washington, fish community to identify potential for exploitative competition, resource partitioning, and predation. The SIA revealed distinct spatial feeding niches; pelagic species were δ13C depleted, while littoral organisms were δ13C enriched. Trophic feeding niches were identified from δ15N enrichment with each successive trophic level. We found δ15N progression with increasing largemouth bass size, suggesting ontogenetic diet variability. Model results suggested that the smaller bass (i.e., ≤299 mm length) fed principally on golden shiner, crayfish, and macroinvertebrates while larger bass (≥300 mm) primarily consumed brook trout and golden shiner. Isotopic signatures for golden shiner were intermediary, indicating both pelagic and littoral feeding sources, including phantom midges (nocturnal and pelagic) and damselflies (littoral) as principal diet sources, suggesting possible horizontal diel migration in golden shiner. Pelagic zooplankton was indicated as the most important food source for rainbow trout. Food resources appeared to be partitioned among the Twin Lakes fish community, possibly limiting competitive interactions. Piscivory in largemouth bass was focused on golden shiner and brook trout, suggesting possible top-down regulation of lower trophic levels. Stable isotope analysis and multiple-source mixing models are useful tools that can improve lake and fishery management decisions by providing data on food web dynamics such as competition, resource partitioning, and predation in lakes.
Water quality assessment and ecoregional comparison of a reservoir in east-central IndianaJarmila PopovičováLake and Reservoir Management1040-23810743-81412522009 155 - 166Water quality assessment and ecoregional comparison of a reservoir in east-central Indiana Popoviov, J. 2009. Water quality assessment and ecoregional comparison of a reservoir in east-central Indiana. Lake Reserv. Manage. 25:155-166. This study assessed water quality of a reservoir in an agricultural watershed of east-central Indiana, examined the effects of a thermal and oxygen regime on cycling of nutrients, and compared the results to ecoregional data and reference guidelines. Two locations were monitored biweekly from May through September 2007 for pH, temperature, dissolved oxygen, alkalinity, Secchi disk transparency (SD), chlorophyll a, and nutrient concentrations. The reservoir did not stratify during the monitoring season, although both anoxia and reoxygenation of the hypolimnion were observed. These conditions affected nitrogen (N) and phosphorus (P) cycling because nitrification was found to occur in the hypolimnion, and both internal load and water column mixing affected the concentrations and distribution of P. The reservoir was characterized as a eutrophic water body based on SD, total N and chlorophyll a concentrations, while total P concentrations classified the reservoir as slightly hypereutrophic (TSI = 73). This P overload has shifted the system toward N-limiting conditions (molar TN:TP = 18). Comparison of trophic parameters to Ecoregion 55 data placed this reservoir within the 75th percentile, and all parameters exceeded the U.S. Environmental Protection Agency ecoregional reference guidelines. I discuss a potential restoration of this water body to comply with the ecoregional nutrient criteria and to avoid future deterioration associated with N limitation.
Interactions between nitrogen dynamics and the phytoplankton community in Lake George, Florida, USAMichael F. Piehler; Julianne Dyble; Pia H. Moisander; Andrew D. Chapman; John Hendrickson; Hans W. PaerlLake and Reservoir Management1040-23810743-81412512009 1 - 14Interactions between nitrogen dynamics and the phytoplankton community in Lake George, Florida, USA Piehler, M.F., J. Dyble, P.H. Moisander, A.D. Chapman, J. Hendrickson and H.W. Paerl. 2009. Interactions between nitrogen dynamics and the phytoplankton community in Lake George, Florida, USA. Lake Reserv. Manage. 25:1-14. Nutrient addition bioassays were conducted to examine the relationship between inorganic nutrient enrichment and phytoplankton community structure and function in Lake George in the St. Johns River System, Florida, USA. Additionally, a nitrogen budget for the lake was developed and included data from the period of this study. We identified the factors that affected cyanobacterial productivity, prevalence, and nitrogen (N2) fixation. The importance of N2 fixation to the nitrogen (N) budget of the system was also assessed. We hypothesized that N2 fixation significantly contributed to the Lake George N budget and that changing the nutrient conditions in manipulative experiments would affect rates of N2 fixation and composition of the phytoplankton, particularly the N2-fixing community. Phytoplankton primary productivity in Lake George was stimulated by the addition of both N and phosphorus (P). Phytoplankton biomass accumulation was most often enhanced by the combined addition of N and P; however, N alone was also often stimulatory. When detected, N2 fixation was always stimulated by P additions. Short-term changes in phytoplankton community composition included taxonomic shifts in response to nutrient manipulations. Fixation of N2 appeared to be a significant contributor to the N load to the lake. Human impacts that change the loading of N, P, or both N and P to Lake George may affect phytoplankton community structure (composition and biomass) and function (primary productivity and N2 fixation). These changes could have consequences for biogeochemical cycling in Lake George and potentially through the freshwater-marine continuum. Continuing nutrient management efforts in this and other similar systems must account for the activity of N2-fixing cyanobacteria, as products (carbon fixation) and drivers (sources of new nitrogen) of eutrophication.
Sedimentary phosphorus in a cascade of five reservoirs (Lozoya River, Central Spain)Pilar Lopez; Rafael Marcé; Jaime Ordoñez; Iñaki Urrutia; Joan ArmengolLake and Reservoir Management1040-23810743-81412512009 39 - 48Sedimentary phosphorus in a cascade of five reservoirs (Lozoya River, Central Spain) Lopez, P., R. Marc, J. Ordoez, I. Irrutia and J. Armengol. 2009. Sedimentary phosphorus in a cascade of five reservoirs (Lozoya River, Central Spain). Lake Reserv. Manage. 25:39-48. The concentration of phosphorus (P), carbon (C), and nitrogen (N) in superficial sediments in a cascade of five reservoirs (Pinilla, Riosequillo, Puentes Viejas, El Villar, and El Atazar) located along the Lozoya river (Central Spain) was determined. The mean reservoir values of sedimentary phosphorus, nitrogen, and carbon increased from the first reservoir (Pinilla) to the central one (Puentes Viejas) where they reached 62 μ molP/g(dw), 5.36 mmolC/g(dw)and 0.56 mmolN/g(dw), respectively. They then followed a decreasing trend until the last reservoir (El Atazar), which presented concentrations close to those of Pinilla. Phosphorus and nitrogen usually tended to increase from the river end to the dam at each reservoir, while carbon did not show a regular trend associated to the river flow. The amount of phosphorus accumulated in sediments of the Lozoya System reservoirs was notably high (> 50 μ molP/g (dw)), especially at the three central reservoirs (Riosequillo, Puentes Viejas, and El Villar). Sedimentary phosphorus was positively related to nitrogen, small particles (∅: 2-10 μ m), and the ratio of iron to aluminium, Fe/Al, is an indicator of iron precipitation. This last variable explained more than 90% of the sedimentary phosphorus variance in four reservoirs (Pinilla, Riosequillo, El Villar, and El Atazar). In the other reservoir (Puente Viejas), sedimentary phosphorus (Psed) variance was explained by Fe/Al ratio as a main factor, but also by nitrogen as a secondary factor. Hence, association of sedimentary phosphorus to iron oxides with small size appeared as the main factor determining phosphorus accumulation in the sediments of the Lozoya reservoirs. Two main management recommendations arise from these results: (1) reduction in the flow of anoxic water from upstream reservoirs to prevent the transport of dissolved phosphate coming from internal loading, and (2) reduction in high flows that carry fine sediment particles with weakly bound P that may be released when the particle meets a new concentration of soluble reactive phosphorus in the downstream reservoirs.
Reconstructing the history of sediment accumulation in the Yesa reservoir: an approach for management of mountain reservoirsAna Navas; Blas Valero-Garcés; Leticia Gaspar; Javier MachínLake and Reservoir Management1040-23810743-81412512009 15 - 27Reconstructing the history of sediment accumulation in the Yesa reservoir: an approach for management of mountain reservoirs Navas, A., B. Valero-Garcs, L. Gaspar and J. Machn. 2008. Reconstructing the history of sediment accumulation in the Yesa reservoir: an approach for management of mountain reservoirs. Lake Reserv. Manage. 25:15-27. The Aragn River was impounded at the foothills of the Pyrenean Internal Depression in 1959; since then sediments accumulations have decreased the reservoir storage capacity. In this work, we interpreted the history of the sediment accumulation in the Yesa reservoir based on the detailed study of two sediment cores collected at the more stable area in the reservoir. The identification of main sedimentological facies together with the analysis of the grain size distribution of the materials accumulated at the bottom of the reservoir was used for interpretations of the sedimentary dynamics. These data were compared with records of known flood events to derive a tentative chronology of the infilling process by assigning main changes observed in the facies types and sediment components to specific years. In addition to grain size data of sediments accumulated in the river channels, suspended sediments from representative sites of the Aragn Basin to the Yesa reservoir were collected during high and low waters and analysed. Grain size data and sediment composition (organic matter, carbonates) were used to assess the characteristics and the pattern of the sediment transport through the Aragn River network and the role played by lithology and land use. The results provide information on the sediment transport. This approach can be used to assess the siltation processes in Mediterranean mountain reservoirs to improve the management of water bodies by preventing their infilling.
Model of zebra mussel growth and water quality impacts in the Seneca River, New YorkDavid Glaser; James R. Rhea; Daniel R. Opdyke; Kevin T. Russell; C. Kirk Ziegler; Wen Ku; Li Zheng; Joseph MastrianoLake and Reservoir Management1040-23810743-81412512009 49 - 72Model of zebra mussel growth and water quality impacts in the Seneca River, New York Glaser, D., J.R. Rhea, D.R. Opdyke, K.T. Russell, C.K. Ziegler, W. Ku, L. Zheng and J.J. Mastriano. 2009. Model of zebra mussel growth and water quality impacts in the Seneca River, New York. Lake Reserv. Manage. 25:49-72. A dynamic water quality model was developed to support management decision-making for the Seneca River, New York. The model incorporated two-dimensional hydrodynamics to simulate stratification observed within the system, a carbon-based zebra mussel growth model to account for the impact of this invasive species on water quality within the system, and a mechanistic representation of sediment diagenesis to account for zebra mussel-induced changes in carbon cycling. The Seneca River is on New York State's 303(d) list of impaired water bodies for nonattainment of dissolved oxygen criteria and is being considered as the potential receiving water for diverted effluent from an 85 million gallon per day (MGD) wastewater treatment plant (WWTP) serving the City of Syracuse, New York. The model was developed to examine the feasibility of such a diversion. The model was parameterized using site-specific field and laboratory studies and accurately simulated six years of routine, generally biweekly, river monitoring data for dissolved oxygen, chlorophyll-a, nitrogen, and phosphorus, collected over a range of flow conditions. The diagnostic application of the calibrated model provided valuable insights into the complex feedback mechanisms that exist within the system, particularly the role that zebra mussel filtration, respiration, and elimination have on phytoplankton production, sediment oxygen demand, and nutrient cycling within the system.
Evaluation of optimal dose and mixing regime for alum treatment of Matthiesen Creek inflow to Jameson Lake, WashingtonJillian J. Churchill; Marc W. Beutel; Peter S. BurgoonLake and Reservoir Management1040-23810743-81412512009 102 - 110Evaluation of optimal dose and mixing regime for alum treatment of Matthiesen Creek inflow to Jameson Lake, Washington Churchill, J.J., M.W. Beutel and P.S. Burgoon. 2009. Evaluation of optimal dose and mixing regime for alum treatment of Matthiesen Creek inflow to Jameson Lake, Washington. Lake Reserv. Manage. 25:102-110. An innovative method of reducing external phosphorus (P) loading to lakes uses engineered systems to treat lake inflows with aluminum sulfate (alum). In this study we used a series of jar tests to examine the optimal alum dose and mixing regime to remove P from Matthiesen Creek, an important external source of P to Jameson Lake. Matthiesen Creek is a good candidate for alum treatment because the creek runs year round, and the majority of P in the spring-feed creek is in the form of bioavailable dissolved P that can be efficiently captured in alum floc. The mixing regimes in this study mimicked a range of possible treatment scenarios that relied on natural turbulence in the creek or conventional mechanical mixing, and presumed the discharge of alum floc either directly to the lake or to an on-shore settling basin. Jar tests showed that an alum dose of 5 mg-Al/L was sufficient to decrease P from around 0.13 mg-P/L to below 0.02 mg-P/L for most mixing regimes. For all mixing regimes, doses of up to 20 mg-Al/L did not depress pH below the recommended minimum pH of 6. Flash mixing prior to low-intensity mixing did not enhance P removal over low-intensity mixing alone, but flash mixing alone resulted in lower levels of P removal from creek water. Jar testing with a mixture of alum-treated creek water and lake water showed that lake waters tended to inhibit P uptake by alum floc. This, combined with the fact that high pH favors the formation of the aluminate ion which could exhibit chronic toxicity to aquatic biota, suggests that discharge of alum solids directly to the lake should be avoided. We recommend an engineered inflow treatment system on Matthiesen Creek that maintains an alum dose of 5-10 mg-Al/L under moderate mixing conditions (Gt of 1,000-3,000) with alum floc collected in an on-shore settling basin.
Phytoplankton dynamics in a chain of subtropical blackwater lakes: the Upper St. Johns River, Florida, USAMillard M. Fisher; Steven J. Miller; Andrew D. Chapman; Lawrence W. KeenanLake and Reservoir Management1040-23810743-81412512009 73 - 86Phytoplankton dynamics in a chain of subtropical blackwater lakes: the Upper St. Johns River, Florida, USA Fisher, M.M., S.J. Miller, A.D. Chapman and L.W. Keenan. 2009. Phytoplankton dynamics in a chain of subtropical blackwater lakes: the Upper St. Johns River, Florida, USA. Lake Reserv. Manage. 25:73-86. Spatial and seasonal patterns in phytoplankton biovolume and community composition were examined for a chain of lakes in the Upper St. Johns River (USJR), Florida, USA. There was a general downstream trend in both increasing phytoplankton biovolume, and dominance of the algal community by cyanobacteria. Total algal biovolume increased from 0.7 106μ m3/ml in the headwaters lake to 5.6 106μ m3/ml downstream in Lake Winder. Cyanobacteria dominated the downstream lakes, accounting for approximately 50% of total algal biovolume, yet constituted only 2% of total biovolume in the headwaters lake. The diatom assemblage, as well as water quality data, suggests that these blackwater lakes are mesotrophic to eutrophic and neither nitrogen nor phosphorus limited growth. Fifteen months of cyanobacterial biovolume data were compared to water quality data to determine principal regulating factors. A regression model indicates that the major factors correlated with cyanobacteria in these lakes are temperature, total Kjeldahl nitrogen, water level, and color, with temperature alone accounting for 54% of the variability in cyanobacterial biovolume. This analysis demonstrates that multiple interacting factors need to be considered when attempting to explain spatiotemporal patterns in algal dynamics.
The effects of residential docks on light availability and distribution of submerged aquatic vegetation in two Florida lakesKym Rouse Campbell; Rick BairdLake and Reservoir Management1040-23810743-81412512009 87 - 101The effects of residential docks on light availability and distribution of submerged aquatic vegetation in two Florida lakes Campbell, K.R. and R.Baird. 2009. The effects of residential docks on light availability and distribution of submerged aquatic vegetation in two Florida lakes. Lake Reserv. Manage. 25:87-101. This study was conducted to determine the effects of residential docks on the density and diversity of submerged aquatic vegetation (SAV) within two freshwater lakes in Orange County, Florida: Lake Butler and Lake Jessamine. From a lake manager's perspective, an improved understanding of the effects of docks should result in better planning and management to help ensure that additional docks do not harm the aquatic environment, while still providing reasonable access to the water. Major issues considered in this study included whether the amount of light penetrating beneath a dock affected the density and diversity of SAV growing beneath it, and whether other variables affected the density and diversity of SAV beneath docks, including lake trophic status. Ten docks and 10 reference sites were surveyed in each lake in June and July 2007. During each survey, we collected numbers and species of SAV, field water quality, surface and underwater light, dock measurements, and surrounding condition information. We documented a reduction in available light under docks with a corresponding decrease in plant density. Density of SAV was higher under docks oriented north/south compared to those oriented east/west. Overall, turbidity had the most influence on SAV diversity, while Secchi depth had the most influence on SAV diversity under docks. For this investigation overall, including beneath docks, SAV density was most affected by the percent of surface light above the SAV/bottom, while SAV diversity was most affected by the clarity of the water.
Spatial disconnection of plankton dynamics in an Ozark reservoirJohn E. Havel; Russell G. RhodesLake and Reservoir Management1040-23810743-81412512009 28 - 38Spatial disconnection of plankton dynamics in an Ozark reservoir Havel, J.E. and R.G. Rhodes. 2009. Spatial disconnection of plankton dynamics in an Ozark reservoir. Lake Reserv. Manage. 25:28-38. This two-year study examined spatial distribution and seasonal population dynamics of algae and zooplankton in Table Rock Lake (Missouri, USA), a large clear reservoir threatened by increased development in the watershed. Regular samples were collected from a polymictic up-lake site (10 m deep, mean Secchi transparency 1.0 m) and a monomictic down-lake site (37 m deep, 4.0 m Secchi) in the productive James River arm. Average abundance and biovolume of most algae groups showed no statistically-discernable difference between these two sites, and maximum cell densities were similar in magnitude (∼ 105 cells/mL). Exceptional were the chlorophytes, which had their highest abundance up-lake. Based on taxonomic composition, both sites appear to be dominated by pelagic algae, with little evidence of riverine immigrants. Algae and zooplankton showed rapid seasonal changes in total densities and composition, and peak abundances showed no association in time between the two sites. Although no floating or suspended colonies were ever visible in the field, cyanobacteria (particularly Oscillatoria) were common at both study sites, and we found numerous genera linked to nuisance blooms in other lakes. Zooplankton communities differed between sites, with cladocerans common in winter and spring at the down-lake site and rotifers common year round at the up-lake site. Important cladoceran grazers, such as Daphnia, were usually not abundant; however, when they were common, algae abundance was always low.
Role of contemporary and historic vegetation on nutrients in Missouri reservoirs: implications for developing nutrient criteriaJohn R. Jones; Matthew F. Knowlton; Daniel V. Obrecht; Anthony P. Thorpe; James D. HarlanLake and Reservoir Management1040-23810743-81412512009 111 - 118Role of contemporary and historic vegetation on nutrients in Missouri reservoirs: implications for developing nutrient criteria Jones, J.R., M.F. Knowlton, D.V. Obrecht, A.P. Thorpe and J.D. Harlan. 2009. Role of contemporary and historic vegetation on nutrients in Missouri reservoirs: implications for developing nutrient criteria. Lake Reserv. Manage. 25:111-118. Using vegetative survey records from the time of Euro-American settlement (circa 1815-1850) we found the proportion of historic prairie accounted for 42% of cross-system variation in total phosphorus (TP) and 48% of total nitrogen in 156 Missouri reservoirs. When combined with dam height (surrogate for lake morphometry) and hydraulic flushing rate (TP only), 56% of variation in nutrients was explained. Consistent with previous analyses, some two-thirds of variation in nutrients was accounted for by contemporary cropland, morphometry, and hydrology (TP only). Adding prairie or historic forest cover to models based on current cropland did little to increase explained variation. The relationship between reservoir nutrients and land cover is partly an artifact of past land conversion; most arable soils with inherent fertility sufficient to generate economically viable produce and suitable topography were former prairies. The cross-system analysis of Missouri reservoirs showed that nutrients in these anthropogenic ecosystems are largely determined by nonpoint input from current land use as modified by morphology and hydrology. Historic vegetation cover, however, was our best measure of baseline conditions in the reservoir catchments and contributes to the framework for developing nutrient criteria for these artificial lakes. No natural reference conditions exist for Missouri reservoirs, and we recommend setting site-specific nutrient criteria for these constructed systems.
Sedimentary and historical context of eutrophication and remediation in urban Lake McCarrons (Roseville, Minnesota)Amy MyrboLake and Reservoir Management1040-23810743-81412442008 349 - 360Sedimentary and historical context of eutrophication and remediation in urban Lake McCarrons (Roseville, Minnesota) Geochemical analysis of the varved (annually laminated) sediments of a small, deep urban lake in east-central Minnesota shows that some water-quality and watershed indicators are approaching prehistoric (pre-1850s) values after an excursion to anomalous levels during the 1920s through 1950s. This high-resolution paleolimnological information (annually resolved for most of the 20th century), including varve thickness measurements on a digital image, carbon stable isotopic composition of organic matter, and sedimentary component quantification, provides historical perspective to lake managers planning remedial measures with reference to the “natural” state of the lake, especially in regard to the perception that water quality has declined only in recent decades (i.e., in the late 20th century). The lake is at present eutrophic and oligomictic, with oxygen-depleted bottom waters enriched in dissolved solids relative to surface waters; an alum treatment has contributed to the problem of persistent stratification at the same time as it has reduced phosphorus and increased transparency in lake surface waters. The sedimentary record shows the lake's strong response to agricultural, recreational, and urban development in the watershed, gradual improvement beginning at the time of sanitary sewer installation in the 1960s, and only a minor additional response to a concerted remediation effort in the mid-1980s to 1990s. Indices of terrestrial inputs and algal productivity show evidence of a lake that was at its most heavily impacted during the mid-20th century, and which has improved in some respects since the 1960s.
Water quality modeling of the effects of macrophytes on dissolved oxygen in a shallow tailwater reservoirJ. Stansbury; L. Kozimor; D. Admiraal; E. DoveLake and Reservoir Management1040-23810743-81412442008 339 - 348Water quality modeling of the effects of macrophytes on dissolved oxygen in a shallow tailwater reservoir Lake Ogallala, a 260-hectare tailwater reservoir, is subject to wide fluctuations of inflow water quality and quantity. These fluctuations impact lake temperatures, water stage, dissolved oxygen (DO), and nutrients. A two-dimensional, continuous simulation hydrodynamic and water quality model, CE-QUAL-W2, was used to simulate dissolved oxygen levels and to quantify DO sources and sinks in the lake. The elements modeled include surges of low DO and temperature; high chemical oxygen demands and dissolved nutrients; response of in-lake algae, macrophytes, and epiphytes; temperature and bathymetric induced circulation patterns; and weather impacts. The model's epiphyte routine was used to simulate macrophytes. The model was able to replicate the diurnal DO fluctuations, which ranged from 2 to 12 mg/L, as well as other water quality parameters. The study found that the chemical oxygen demand depressed daily DO minima by approximately 1.5 mg/L. This study also found that macrophyte respiration was an important factor in the low daily DO minima, depressing daily DO minima approximately 2 mg/L overnight.
Biodiversity in southern Wisconsin storm-water retention ponds: Correlations with watershed cover and productivityStanley I. DodsonLake and Reservoir Management1040-23810743-81412442008 370 - 380Biodiversity in southern Wisconsin storm-water retention ponds: Correlations with watershed cover and productivity This research is based on the management principle that watershed land cover is a better predictor of pond biodiversity than primary productivity. Ponds in watersheds with more than 30% lawn cover have few zooplankton species, no macrophytes, no snails, and no amphibians. A recent meta-analysis generated the hypothesis that watershed (catchment basin) land cover is a better predictor of lake biodiversity than traditional predictors (such as in-lake primary productivity) if the watershed includes human development (agriculture, residential, or urban). This hypothesis was tested via a field survey of 23 similar-sized artificial ponds in southern Wisconsin. The ponds had similar climate and geology, but differed in the relative proportions of land cover in the watershed. Twelve environmental variables (including pond area, depth, and primary productivity surrogates) and seven watershed land cover variables were correlated with biodiversity measures of seven major aquatic communities. Percent lawn cover was negatively correlated with zooplankton richness (r2 = 0.41), macrophyte abundance (r2 = 61), molluscan presence (r2 = 0.48), and amphibian presence (r2 = 0.55 for spring species and r2 = 0.78 for summer species). Fish presence was negatively correlated with percent watershed covered by meadow (r2 = 0.16). Chlorophyll a (a primary productivity surrogate) was negatively correlated with three groups: zooplankton richness (r2 = 0.18), macrophyte abundance (r2 = 0.23), and molluscan presence/absence (r2 = 0.31). Total phosphorus and nitrogen (surrogates of in-lake primary productivity) were weakly correlated with biodiversity.
Predicting Eurasian watermilfoil invasions in MinnesotaSarah S. Roley; Raymond M. NewmanLake and Reservoir Management1040-23810743-81412442008 361 - 369Predicting Eurasian watermilfoil invasions in Minnesota Eurasian watermilfoil is an invasive aquatic macrophyte that can be difficult to control once established in a lake. Identifying characteristics of lakes susceptible to Eurasian watermilfoil establishment can aid management by allowing managers to focus their education and monitoring efforts on susceptible lakes. Using linear discriminant function analysis and logistic regression to analyze known occurrences of Eurasian watermilfoil, we developed models to predict susceptible lakes in Minnesota. The most reliable predictors of Eurasian watermilfoil invasion were distance to the nearest invaded lake and duration of that invasion, indicating that transport (exposure) is an important variable. However, exposure is not a guarantee of establishment: lake size, alkalinity, Secchi depth, and lake depth were also significant predictors of invasion. Specifically, large deep lakes with moderate to high alkalinity and moderate Secchi depth were more likely to be invaded. Models predicted an additional 2,100 to more than 4,700 of Minnesota's more than 12,000 lakes could be invaded by Eurasian watermilfoil.
Effects of sediment resuspension on nutrient concentrations and algal biomass in reservoirs of the Central PlainsAndrew R. Dzialowski; Shih-Hsien Wang; Niang-Choo Lim; Jason H. Beury; Donald G. HugginsLake and Reservoir Management1040-23810743-81412442008 313 - 320Effects of sediment resuspension on nutrient concentrations and algal biomass in reservoirs of the Central Plains Historically, lake and reservoir management has focused on controlling external nutrient loading. However, it is becoming increasingly clear that internal mechanisms, such as the episodic resuspension of benthic sediments, can also contribute to the processes of eutrophication. We conducted laboratory bioassay experiments to determine how resuspended sediments affected nutrient concentrations and algal biomass in four eutrophic reservoirs of the Central Plains. Surficial sediments and surface water were collected from each reservoir and returned to the laboratory where they were added to 1-L bioassay bottles at five turbidity concentrations (0, 50, 150, 250, and 500 NTUs). Sediments in the bioassay bottles were resuspended daily, and algal biomass (measured as relative fluorescence) was measured for 11-14 days. Resuspended sediments at the lowest experimental turbidity concentration, 50 NTUs, had highly significant effects on algal biomass in each of the sediment resuspension bioassays. Algal biomass appeared to increase following experimental sediment resuspension due to an increase in available nutrients and/or the establishment of algae (meroplankton) from the sediment. Overall, our results highlight the importance of considering internal mechanisms when developing reservoir management and restoration plans for these important ecosystems.
Evaluation of the impact of water dilution within the hypereutrophic Lake Barato, JapanRyuichiro Shinohara; Takeshi Okunishi; Kumiko Adachi; Le Son Viet; Hiroaki Mine; Toshihiko Yamashita; Masahiko IsobeLake and Reservoir Management1040-23810743-81412442008 301 - 312Evaluation of the impact of water dilution within the hypereutrophic Lake Barato, Japan Field data and three-dimensional numerical simulations were used to evaluate the impact of water dilution on eutrophication. To dilute eutrophic water in Lake Barato, Japan, an Inlet Project was carried out during the summer of 2005 via a 1 m3/sec inlet. River water was discharged from the margin of the upper basin of the lake to dilute the water. We undertook a numerical simulation of total nitrogen (TN) and total phosphorus (TP) distribution considering five inlet cases by using Princeton Ocean Model (POM). Total N and TP concentrations of inlet water were TN: 1.3 mg/l and TP: 0.08 mg/l. Model results suggest the most effective and feasible way to achieve dilution is via a 5 m3/sec inlet (78% related to the total volume in the lake) and opening the Shinko Gate, connecting the lake with Ishikari Bay. Following this scheme, TN and TP concentrations would be reduced by 28% following 30 days of discharge according to the simulation results.
Lack of exotic hydrilla infestation effects on plant, fish and aquatic bird community measuresMark V. Hoyer; Melissa Woods Jackson; Micheal S. Allen; Daniel E. Canfield Jr.Lake and Reservoir Management1040-23810743-81412442008 331 - 338Lack of exotic hydrilla infestation effects on plant, fish and aquatic bird community measures The invasion of hydrilla into North American lakes has provoked concern over loss of native flora and fauna and resulted in costly suppression efforts. We used two data sets to determine if common measures of ecosystem health; abundance, species richness, diversity and evenness, were affected by the presence of hydrilla. Data Set 1 consisted of 27 Florida lakes, 11 of which had hydrilla present for approximately 4-8 years in varying abundances, and 16 did not have hydrilla. Given the number of lakes, each was sampled only once in the summers of 1986-1990 for community measures of aquatic plants, birds, and fish. Data Set 2 consisted of 12 lakes, six with abundant hydrilla for over 23 years and six without hydrilla. These lakes were sampled every year in the summer (with a few exceptions due to weather conditions) between 1999 and 2006 for community measures of aquatic plants and fish. The results for both data sets show that presence of hydrilla had no statistically significant effect (P > 0.05) on all community measures tested (i.e., richness, diversity, abundance). Our conclusions support the hypothesis that hydrilla in these Florida lakes has occupied a mostly vacant ecological niche and has not affected the occurrence or relative composition of native species of aquatic plants, birds, and fish. Because pond experiments have found negative effects of hydrilla, further focused research is needed to assist management decisions when considerable resources are to be spent each year on hydrilla suppression.
Seasonal changes in the zooplankton abundances of the reservoir Valle de Bravo (State of Mexico, Mexico)S. Nandini; Martín Merino-Ibarra; S. S. S. SarmaLake and Reservoir Management1040-23810743-81412442008 321 - 330Seasonal changes in the zooplankton abundances of the reservoir Valle de Bravo (State of Mexico, Mexico) Valle de Bravo is one of largest drinking water reservoirs in Mexico, serving nearly 12% of Mexico City's population of 26 million. We studied the monthly variations in the zooplankton density and diversity for one year (November 2004 to October 2005) at five different depths (2, 4, 8, 12, and 20 m) at each of the five sites of the reservoir. The water body was generally alkaline; pH decreased with increasing depth. Dissolved oxygen also decreased drastically with depth, from an average of 8 mg/L to less than 1 mg/L. Chlorophyll a concentration varied considerably (2.6 ± 0.06 to 12.5 ± 2.8 μg/L) both seasonally and with depth. Secchi depth averaged 1.65 m and varied between 0.63 and 3.21 m along the seasons but exhibited minimal differences among sites. Differences in zooplankton abundance and composition were small among sites, supporting the theory that anthropogenic disturbances affect the reservoir as a whole. The mean total zooplankton density was about 400 ± 293 ind./L, mostly composed of rotifer species, particularly Keratella cochlearis, Polyarthra vulgaris, and Trichocerca similis. Densities of K. cochlearis at 2-m depth exceeded 1800 ind./L during the rainy season (May-July). Average density of P. vulgaris was 200 ± 133 ind./L, while that of T. similis was half that amount. The dominant cladoceran taxa were Bosmina longirostris, Chydorus sphaericus, and Daphnia laevis. An inverse relationship between depth and zooplankton abundance and depth and diversity was observed. In contrast, we observed a direct relation between the mean rotifer and cladoceran density. Shannon-Wiener's species diversity index ranged between 1.00 and 4.09. Fourteen of the rotifer species found are new records for Valle de Bravo and another 13 species observed earlier were not encountered in the present study. The overall trends in both the densities and dominance of rotifer species of the reservoir did not essentially change during the last five years. Our data point toward the need for an integrated management of Valle de Bravo.
Assessing contribution of DOC from sediments to a drinking-water reservoir using optical profilingBryan D. Downing; Brian A. Bergamaschi; David G. Evans; Emmanuel BossLake and Reservoir Management1040-23810743-81412442008 381 - 391Assessing contribution of DOC from sediments to a drinking-water reservoir using optical profiling Understanding the sources of dissolved organic carbon (DOC) in drinking-water reservoirs is an important management issue because DOC may form disinfection by-products, interfere with disinfection, or increase treatment costs. DOC may be derived from a host of sources—algal production of DOC in the reservoir, marginal production of DOC from mucks and vascular plants at the margins, and sediments in the reservoir. The purpose of this study was to assess if release of DOC from reservoir sediments containing ferric chloride coagulant was a significant source of DOC to the reservoir. We examined the source-specific contributions of DOC using a profiling system to measure the in situ distribution of optical properties of absorption and fluorescence at various locations in the reservoir. Vertical optical profiles were coupled with discrete water samples measured in the laboratory for DOC concentration and optical properties: absorption spectra and excitation emission matrix spectra (EEMs). Modeling the in situ optical data permitted estimation of the bulk DOC profile in the reservoir as well as separation into source-specific contributions. Analysis of the source-specific profiles and their associated optical characteristics indicated that the sedimentary source of DOC to the reservoir is significant and that this DOC is labile in the reservoir. We conclude that optical profiling is a useful technique for understanding complex biogeochemical processes in a reservoir.
Landscape structure and habitat composition in reservoirs, lakes, and riversE. G. Drakou; A. S. Kallimanis; S. P. Sgardelis; J. D. PantisLake and Reservoir Management1040-23810743-81412432008 244 - 260Landscape structure and habitat composition in reservoirs, lakes, and rivers We compared reservoirs that were proposed to be included in the Greek Natura 2000 network of protected sites, with natural lakes and rivers from the same network. We analyzed landscape spatial pattern, habitat type composition, and spatial pattern of human activities. We found that the landscapes of reservoirs are distinct from those of rivers and natural lakes. More specifically, the reservoir water bodies were characterized by a more complex shape than the water bodies of rivers and lakes. Furthermore, based upon the landscape spatial pattern of the entire protected area, we could clearly discriminate among the three aquatic ecosystem types. It was also possible to discriminate these ecosystem types based upon the habitat composition of the surrounding landscape. The habitat composition among the different sites showed low similarity. Human presence in all sites was documented, but its spatial pattern was not differentiated among the three aquatic ecosystem types. The results highlight the ambiguous nature of reservoirs; thus, we advocate the need for specific management measures for reservoirs that will accomplish both their intended purpose and the conservation of habitat composition and landscape structure.
Predicting the spatial mud energy and mud deposition boundary depth in a small boreal reservoir before and after draw downP. M. Cooley; W. G. FranzinLake and Reservoir Management1040-23810743-81412432008 261 - 272Predicting the spatial mud energy and mud deposition boundary depth in a small boreal reservoir before and after draw down We predicted the distribution of coarse- and fine-grained substrata in a small boreal lake at natural lake level and then assessed if the extents of sediment focusing due to water level manipulation could be predicted. The littoral substratum and upper limit to the distribution of mud was mapped completely prior to experimental draw down and the upper depth limit of mud was mapped in each of the first 2 years of a new water level regime. Six published equations for estimating the position of the mud boundary and the lower limit of surface wave energy were applied using maps of fetch, slope, and depth. At natural lake level, the agreement between observed and estimated mud boundaries in deep water was remarkable (<5 m horizontal). Agreement between the depth of mixing by surface waves and mud boundaries in shallow water was closest, at times exact, for equations with estimates similar to maximum wave height. However, the size of waves responsible for the shallow sediment boundaries remains unclear due to natural variation of lake level. All models overestimated energy in shallow depositional settings where exposure and slope was low. Refocusing of sediment due to maximum winter draw down of 3 m resulted in contraction and expansion of the profundal zone; a net decrease in area of 3% was evident after 2 years. Our results demonstrate that mud deposition models can be used in deep lake basins to map the littoral and profundal zones. Sediment refocusing in the first few years of winter draw down is forced mainly by falling lake levels. The interpretation of littoral habitat complexity can be simplified by understanding the lake-wide spatial pattern of erosion, transport, and deposition of sediments.
Probabilistic model for temperature and turbidity in a reservoir withdrawalRakesh K. Gelda; Steven W. EfflerLake and Reservoir Management1040-23810743-81412432008 219 - 230Probabilistic model for temperature and turbidity in a reservoir withdrawal The development and application of a probabilistic modeling framework to conduct a priori simulations (forecasts) of temperature (Tw) and turbidity (Tn,w) in the withdrawal of a water supply impoundment, Schoharie Reservoir, N.Y., is documented. The model framework incorporates previously tested transport/hydrothermal and turbidity submodels, long-term (57 years) records of meteorology, hydrology, and operations, and empirical models to specify other drivers, including tributary temperature and turbidity inputs, over the same period. The probabilistic framework closely simulates the observed wide variations in Tw and Tn,w for an 18-year period. The major sources of variability for both Tw and Tn,w were demonstrated to be variations in hydrologic and linked operating conditions. Application of the probabilistic framework indicates the goal for Tw could be met continuously with a multi-level intake (MLI) facility instead of the existing single, fixed-depth intake. However, this management alternative would provide only modest benefits for Tn,w levels. The model predicts that moving the MLI facility to a deeper portion of the reservoir will not improve the water quality of the withdrawal within the context of management goals.
Minnesota's approach to lake nutrient criteria developmentSteven Heiskary; Bruce WilsonLake and Reservoir Management1040-23810743-81412432008 282 - 297Minnesota's approach to lake nutrient criteria development Ecoregion-based phosphorus “criteria” that reflect the diversity of lake condition, varying from deep pristine lakes in the north to shallow hypereutrophic lakes in the south, were developed by the Minnesota Pollution Control Agency (MPCA) in the late 1980s. Since then the criteria, including several refinements, have been widely used for local, state, and federal lake watershed management efforts in Minnesota. More recently, the criteria have been used to define thresholds for Clean Water Act Section 303(d) listing of nutrient-impaired lakes and are being advanced as lake standards to protect a wide diversity of beneficial uses. This paper summarizes the evolution of these criteria and describes data and research used in their development. A weight-of-evidence approach describes how this information was used to refine the criteria values.
Secchi transparency of Boulder Basin, Lake Mead, Arizona-Nevada: 1990-2007James F. LaBountyLake and Reservoir Management1040-23810743-81412432008 207 - 218Secchi transparency of Boulder Basin, Lake Mead, Arizona-Nevada: 1990-2007 Over 5,500 individual Secchi readings were taken from Boulder Basin of Lake Mead, Nevada-Arizona, between July 1990 and December 2007. Annual and seasonal patterns are plainly displayed by these data. Variations in Secchi depth measurements are both spatial and temporal. Peak water transparency >15 m generally occurs in April and March and at sampling locations along the thalweg of the Colorado River channel in the Outer portion of Boulder Basin. Transparency steadily decreases toward the tributary inflow into Las Vegas Bay. Transparency in open water of Las Vegas Bay ranges from <1 m during the growing season to 5-7 m in winter. These differences are generally driven by varying algal production which decreases in a cline from Las Vegas Bay to the Outer Basin. Entrainment of small sediment particles from the urban inflow also influences water transparency. Steady lowering of the reservoir during the 2000 to 2007 drought exacerbated the influence of turbidity due to entrainment of former lake bottom sediments into the epilimnion. However, the strongest statistical relationships with decreasing Secchi transparency are with chlorophyll a (chl-a) and total phosphorus (TP). The patterns and relationships presented establish the nature of Boulder Basin's water clarity to 2008 that will be useful in light of imminent and future alterations of the aquatic ecosystem by both anthropogenic and nonanthropogenic factors. Perhaps the largest change will occur due to the recent introduction of the quagga mussel (Dresseina rostriformis bugensis). After discovery in January 2007, the mussel population has been increasing rapidly. The data sets in this presentation form the basis of conditions in Boulder Basin prior to the introduction of quagga mussels.
Turbidity and temperature patterns in a reservoir and its primary tributary from robotic monitoring: Implications for managing the quality of withdrawalsAnthony R. Prestigiacomo; Steven W. Effler; David M. O'Donnell; David G. Smith; Donald PiersonLake and Reservoir Management1040-23810743-81412432008 231 - 243Turbidity and temperature patterns in a reservoir and its primary tributary from robotic monitoring: Implications for managing the quality of withdrawals A robotic water quality monitoring network, consisting of 2 in-reservoir profiling platforms and a unit positioned in the primary tributary, was used to document patterns of temperature (T) and turbidity (Tn) and the impact of runoff events on Tn levels over the spring to fall interval of 3 years. The patterns were evaluated in the context of water quality goals for T and Tn for reservoir withdrawal and potential benefits of specified management alternatives. Exceedences of a proposed withdrawal T goal of 21.1 °C (70 °F) and a conservative representation of the Tn goal of 15 NTU were demonstrated. The exceedences occurred in late summer during intervals of extensive drawdown for T and irregularly following runoff events for Tn. Conspicuous increases in Tn in the tributary and lacustrine portions of the reservoir were demonstrated in response to all monitored runoff events (n = 34). Lacustrine levels exceeded 75 NTU following several major events. The turbidity load from the tributary usually enters the reservoir as a turbid density current during runoff events, at a depth predicted well by stream temperature. The high frequency and vertical resolution attributes of the robotic monitoring (2 profiles per day for reservoir deployments) were invaluable in resolving impacts because these were usually attenuated within a week following events. The diminishment of reservoir Tn levels following events was demonstrated to be well represented by a first-order loss rate. The loss rate for the largest runoff event of the study (return interval ~25 y) was more than an order of magnitude lower than any other, indicating a difference in settling attributes of turbidity-causing particles for this extreme case. Benefits from a shift to delayed withdrawals for the existing intake, or installation of a multi-level intake facility, for improving status with respect to the water quality goals are suggested from the monitoring data. However, continuously meeting the Tn goals for particularly severe events may not be feasible through these approaches.
Nutrient budgets and river impoundments: Interannual variation and implications for detecting future changesJ. A. Ferris; J. T. LehmanLake and Reservoir Management1040-23810743-81412432008 273 - 281Nutrient budgets and river impoundments: Interannual variation and implications for detecting future changes Temporal variability at monthly and annual scales was quantified at the inlets and outlets of 3 sequential impoundments for total phosphorus, dissolved phosphorus (TP), total nitrogen (TN), dissolved nitrogen, particulate nitrogen, colored dissolved organic matter, specific conductance, and pH over three years. Chlorophyll a (Chl-a) was measured within the largest of the 3 impoundments; Secchi disk transparency depth was measured over 9 years. The data were analyzed to characterize “ordinary” temporal variability, and statistical models were constructed to evaluate the sampling effort that would be required to detect predicted changes in response to a municipal ordinance banning phosphorus in lawn fertilizers, as well as to possible removal of the dam forming the middle impoundment. Changes of 25% in monthly mean value would require weekly samples during the summer for only 1 or 2 years for TN and TP, but about 8 years for Chl-a to achieve statistical confidence that conditions had changed. Bioassay experiments in the most upstream and largest of the 3 impoundments indicated that water residence times are in general too short to permit phytoplankton the opportunity to develop populations large enough to alter biogeochemistry substantially in any of the impoundments. Mass balance calculations tended to confirm this conclusion; the reservoirs acted neither as nutrient sources nor sinks over the period of study.
Short-term effects of a buffered alum treatment on Green Lake sediment phosphorus speciationRebecca A. Dugopolski; Emil Rydin; Michael T. BrettLake and Reservoir Management1040-23810743-81412422008 181 - 189Short-term effects of a buffered alum treatment on Green Lake sediment phosphorus speciation Green Lake, Washington, was treated with a dose of 24 mg Al/L aluminum sulfate (alum) and sodium aluminate during March-April 2004 to reduce dissolved phosphorus concentrations to ameliorate a variety of eutrophication-related problems. Four sediment cores collected six months after the alum treatment in Green Lake were used to examine the short-term effects of alum on sediment phosphorus speciation. Peaks in aluminum bound phosphorus (Al-P) and total aluminum (Tot-Al) were observed in three of the four cores analyzed, resulting in an average ratio of added Al to Al-P formed (Al:Al-P) of 112:1. By comparing this ratio to the average ratio of ~11:1 found in other alum-treated Washington lakes, it can be inferred that approximately 10% of the binding capacity of the added Al had been utilized. Assuming a final ratio of Al:Al-P of 11:1, the added Al has the potential capacity to bind a total of 21.6 g/m2 of P. The amount of sediment inorganic P that supports internal loading (Fe-P and labile-P) in the fall of 2004 was determined to be 2.8 g/m2. Thus the quantity of alum added to Green Lake should be sufficient to inactivate the remaining inorganic mobile-P and to control future P mobilization from the pool of organic sediment P.
Nutrients, seston, and transparency of Missouri reservoirs and oxbow lakes: An analysis of regional limnologyJohn R. Jones; Daniel V. Obrecht; Bruce D. Perkins; Matthew F. Knowlton; Anthony P. Thorpe; Shohei Watanabe; Robert R. BaconLake and Reservoir Management1040-23810743-81412422008 155 - 180Nutrients, seston, and transparency of Missouri reservoirs and oxbow lakes: An analysis of regional limnology A long-term (1978-2007) summer monitoring study of 167 Missouri reservoirs and floodplain lakes shows wide ranges in the trophic state variables total phosphorus (TP; 6-395 μg/L for reservoir means), total nitrogen (TN; 200-3290 μg/L), chlorophyll (Chl; 1-223 μg/L) and Secchi depth (0.15-4.3 m). There are strong regional contrasts between eutrophic-hypereutrophic water bodies in the predominantly agricultural Osage Plains, Glaciated Plains and Big Rivers sections and the mostly oligotrophic-mesotrophic reservoirs in the largely forested Ozark Highlands. The ecotonal Ozark Border was intermediate. Missouri reservoirs had slightly less TN relative to TP than predicted by global models, but TN:TP (median = 18.4) is typical of North American lakes and was about five- fold lower in the most enriched reservoirs compared to the least enriched ones. Concentrations of seston, measured as total suspended solids (TSS), volatile suspended solids (VSS), nonvolatile suspended solids (NVSS), filterable (small) suspended solids (fTSS) and the sum of all fractions (ΣTSS), were strongly correlated with TP, TN, and Secchi depth. The proportion of mineral seston (NVSS, fTSS) increased with TSS and was the dominant fraction in most reservoirs, especially in the agricultural regions. Phytoplankton was dominated by small forms (<11 μm), and Cyanophyta were the most common algae comprising a median 46% of phytoplankton biovolume. Chlorophyll-nutrient regressions showed a dominant effect of TP (r2 = 0.83 for reservoir means) with a lesser, negative effect of mineral seston (NAS or fTSS, partial r2 ~ 0.05). Secchi depth was more strongly controlled by mineral seston than by phytoplankton such that Secchi was a better predictor of nutrients (especially TP) than algal biomass. Frequency of algal blooms (Chl >10 μg/L) and Secchi <1 m increased sigmoidally with TP and TN with midrange nutrient concentrations (TP 20-50 μg/L, TN 400-700 μg/L) showing the greatest response to change. Trophic state criteria appropriate for Missouri reservoirs are similar to other north temperate lakes except for Secchi depth for which cutpoints are much lower because of nonalgal turbidity.
The effects of water level fluctuations and some physical and chemical variables on the macrophyte density in Lake Işıklı, TurkeyCengiz KoçLake and Reservoir Management1040-23810743-81412422008 196 - 206The effects of water level fluctuations and some physical and chemical variables on the macrophyte density in Lake Iıklı, Turkey The effects of water level fluctuations and some water quality variables of Lake Iıklı (western Turkey) on the density of water macrophytes were investigated between 1987 and 2005. Water depth, light transmission, suspended solids, and macronutrients were analyzed to determine the water quality of the lake and compared to dry and wet biomass of macrophytes. Light transmission and water level were identified as the main factors for the increase of macrophyte density in the lake. At minimum surface elevations, the decline in lake surface area accompanied the density-dependent decline of macrophytes during the September-November period. Subsequent increased surface elevation (in March-May) also restricted the plant growth through decreased light availability.
Monitoring periphyton in lakes experiencing shoreline developmentDaniel Lambert; Antonella CattaneoLake and Reservoir Management1040-23810743-81412422008 190 - 195Monitoring periphyton in lakes experiencing shoreline development Early detection of degradation is crucial in previously pristine lakes experiencing residential development along their shores. Despite suggestions that the littoral zone responds to anthropogenic disturbance before open water, the use of periphyton for monitoring lake trophic status has been hindered by the heterogeneous distribution of this community. We examined the response of periphyton growing on different natural substrata — rocks, wood, sediments, and macrophytes — as well as on introduced plastic strips along a gradient of residential development in the Laurentian lakes (Quebec). We measured periphyton biomass as chlorophyll a and as thickness estimated with a ruler with the goal to evaluate the best method to monitor the incipient degradation of these lakes. Our findings suggest that rocks are the best substratum to sample because they are ubiquitous, and epilithic algae show a stronger response to shoreline residential development than algae on other substrata. Measurement of epilithon thickness appears a fast and reliable tool for estimating epilithon biomass. If measurements of chlorophyll a require several field and laboratory manipulations that are not readily available for voluntary lake monitoring by residents, measurement of periphyton thickness on rocks may allow examining spatial and temporal changes in a large number of lakes.
Modeling the influence of land use on groundwater chloride loading to lakesPaul M. McGinleyLake and Reservoir Management1040-23810743-81412422008 112 - 121Modeling the influence of land use on groundwater chloride loading to lakes Concern over potential ecological impacts of rising chloride concentrations in lakes has intensified interest in predicting how chloride concentrations in lakes will change over time. Since the 1970s, chloride concentrations have risen in a group of central Wisconsin lakes. The principal source of water to these lakes is groundwater, and rising chloride concentrations have coincided with increased chloride use within the groundwater contributing areas. A groundwater lake loading model was developed to show how chloride sources in groundwater-contributing areas change chloride concentrations in lakes. By using this model with measured chloride concentrations from the lakes, the chloride exported from different land uses was estimated. Chloride export from agricultural and residential land uses was estimated to be 41 kg/ha·yr and 51 kg/home·yr, respectively. Highway deicing was determined to be a minor source of chloride to these lakes due to the low density of primary roads. Chloride concentrations will increase in these lakes until they are at steady-state with respect to chloride loading. The groundwater lake loading model showed that concentrations in these lakes average 50% of their predicted steady-state concentrations, but individually they range from <10% to >90% of their ultimate concentrations.
Growth, condition, diet, and consumption rates of northern pike in three Arizona reservoirsJon M. Flinders; Scott A. BonarLake and Reservoir Management1040-23810743-81412422008 99 - 111Growth, condition, diet, and consumption rates of northern pike in three Arizona reservoirs Northern pike (Esox lucius L.) introductions are controversial in the western United States due to suspected impacts they might have on established sport fisheries and potential illegal introductions. Three Arizona reservoirs, Parker Canyon Lake, Upper Lake Mary and Long Lake were sampled to examine the diet, consumption dynamics, and growth of northern pike. Northern pike diets varied by season and reservoir. In Parker Canyon Lake, diets were dominated by rainbow trout in winter and spring and bluegill and green sunfish in the fall. In Long Lake the northern pike ate crayfish in spring and early summer and switched to young of the year common carp in summer and fall. Black crappie, golden shiners, and crayfish were the major prey in Upper Lake Mary during spring, but they switched to stocked rainbow trout in the fall. Northern pike growth was in the high range of growth reported throughout the United States. Estimated northern pike specific consumption rate (scr) of rainbow trout (g/g/d 10-6) was greatest in Upper Lake Mary (scr = 329.1 ± 23.7 g/g/d 10-6) where stocked fingerling (<120 mm total length [TL]) rainbow trout were most vulnerable to these predators, compared to larger (>280 mm TL) rainbow trout stocked in Long Lake (scr = 1.4 ± 0.1 g/g/d 10-6) and Parker Canyon Lake (scr = 287.2 ± 15.1 g/g/d 10-6) where catchable-sized rainbow trout were stocked. Managers should consider the cost-benefits of stocking fish >200 mm TL in lakes containing northern pike.
Development of phosphorus load reduction goals for seven lakes in the Upper Ocklawaha River Basin, FloridaRolland S. Fulton III; Dale SmithLake and Reservoir Management1040-23810743-81412422008 139 - 154Development of phosphorus load reduction goals for seven lakes in the Upper Ocklawaha River Basin, Florida External phosphorus loading targets have been developed for seven lakes in the Upper Ocklawaha River basin (UORB), and for six of these lakes the loading targets have been used as a basis for total maximum daily loads (TMDLs). External phosphorus loads for the seven lakes were estimated from 1986-2005. Three of the lakes that have received partial reductions in external loads have shown proportional reductions in phosphorus concentrations. Natural background phosphorus concentrations for the lakes were determined through a weight-of-evidence approach combining existing concentrations in reference lakes and modeling of natural background conditions in the basin. Target phosphorus concentrations were established by allowing a 10% degradation from natural background water transparency, as specified in Florida water quality standards. Data collected from the UORB lakes were analyzed to determine the relationship between phosphorus concentrations and water transparency. Target phosphorus concentrations ranged from 14-32 μg/L, which range from 15-100% of existing concentrations in the lakes. Recommended external phosphorus load reductions for the lakes range from 0 to 85%. We estimated that meeting the target phosphorus concentrations in the lakes with poorest water quality would reduce mean chlorophyll a concentrations up to 80%, substantially reduce algal bloom frequencies, and more than double mean Secchi transparency.
Implications of redox processes for the rehabilitation of an urban lake, Onondaga Lake, New YorkSteven W. Effler; David A. MatthewsLake and Reservoir Management1040-23810743-81412422008 122 - 138Implications of redox processes for the rehabilitation of an urban lake, Onondaga Lake, New York A synthesis of the impacts of domestic and industrial wastes on oxygen resources and redox conditions of polluted Onondaga Lake, Syracuse, N.Y., is presented based on a long-term (1978-2005) monitoring program. Insights from this retrospective analysis are used to evaluate management alternatives for the remediation of oxygen resources and redox conditions. Reduced byproducts of anaerobic metabolism accumulated annually in the hypolimnion, causing low dissolved oxygen (DO) concentrations in the upper waters during fall turnover. The high natural sulfate (SO42-) concentration of the lake promoted DO depletion and the production of methylmercury (CH3Hg+). Severe depletions of DO occurred annually in the upper waters during fall mixing, representing violations of water quality standards for extended intervals from 1978 to 1996. Depletions of DO during fall were less severe from 1997 to 2004. The improvement is reported to be in response to: (1) more routine occurrence of spring turnover following closure of an industry; (2) reduction in primary productivity; (3) return of large bodied Daphnia from closure of the industry; (4) satisfaction of historic debt from earlier higher primary production levels; and (5) year-round nitrification at a contributing domestic wastewater facility. Additional improvements in oxygen resources and decreases in SO42- reduction are anticipated based on mandated future upgrades of phosphorus and ammonia treatment at the wastewater facility. Prevailing DO conditions during fall turnover, particularly within the context of anticipated improvements from the mandated upgrades, indicate hypolimnetic aeration or oxygenation is not required to meet water quality goals. Amendments to the hypolimnetic pool of NO3- are recommended instead of aeration or oxygenation to inhibit production of CH3Hg+ by SO42- reducing bacteria.
Seasonal increases in polycyclic aromatic hydrocarbons related to two-stroke engine use in a small Alaskan lakeStanley D. Rice; Larry Holland; Adam MolesLake and Reservoir Management1040-23810743-81412412008 10 - 17Seasonal increases in polycyclic aromatic hydrocarbons related to two-stroke engine use in a small Alaskan lake To determine if hydrocarbon levels in salmon-rearing lakes are affected by seasonal increases in the number of two-stroke powered watercraft, passive hydrocarbon sampling devices were deployed in Auke Lake in southeast Alaska for five successive summers (1999-2003). Estimates of the number of two-stroke powered water craft were made by daily census in 2003. Passive samplers mimic the bioconcentration of trace waterborne lipophilic contaminants by living organisms and are used worldwide for in situ monitoring of organic contaminants such as polycyclic aromatic hydrocarbons (PAHs). Monthly increases in PAHs coincided with monthly increases in the number of two-stroke powered watercraft (jet skis and powerboats) on the lake during the summer. This increase in PAHs varied in magnitude from year to year. PAHs were detected in the surface waters (1 m), particularly in high use areas, and were not detected at 9 m depth. These localized seasonal inputs appeared to come primarily from recreational watercraft rather than from runoff. Alaska's recreational boating season is very compressed and coincides with migrations of anadromous fish. Increased use of two-stroke engines may transfer enough hydrocarbons to the lake to affect fish populations.
Effects of oxygen and nitrate on nutrient release from profundal sediments of a large, oligo-mesotrophic reservoir, Lake Mathews, CaliforniaMarc W. Beutel; Alex J. Horne; William D. Taylor; Richard F. Losee; Randy D. WhitneyLake and Reservoir Management1040-23810743-81412412008 18 - 29Effects of oxygen and nitrate on nutrient release from profundal sediments of a large, oligo-mesotrophic reservoir, Lake Mathews, California Lake Mathews is a large, oligo-mesotrophic reservoir located in Southern California. The reservoir has elevated levels of nitrate and periodically experiences hypolimnetic anoxia. Experimental sediment-water chamber incubations and reservoir water quality monitoring were conducted to evaluate how oxygen and nitrate in overlaying water affect nutrient release from profundal sediments and internal nutrient loading. In experimental incubations, under nitrate-free anoxic conditions, sediment nutrient release rates were 3.4 ± 0.8 mg-P/m2 ·d for phosphate and 2.8 ± 1.2 mg-N/m2 ·d for ammonia (average ± standard deviation; n = 6). Oxygen repressed phosphate release and greatly diminished ammonia release from sediments in experimental incubations while nitrate only repressed phosphate release. Similar nutrient release dynamics were observed in the reservoir. Nutrient release rates estimated from seasonal nutrient profiles collected from the reservoir were 3.4 mg-P/m2 ·d for phosphate and 2.5 mg-N/m2 ·d for ammonia. Ammonia accumulation in the hypolimnion commenced with the onset of anoxic conditions, but phosphate accumulation did not start until nitrate disappeared from bottom waters approximately 6 weeks later. The time lag decreased total internal phosphorus loading by approximately 25% relative to hypothetical nitrate-free conditions. Laboratory and field data show that both oxygen and nitrate repress sediment phosphate release, likely via the maintenance of an oxidized surficial sediment layer that retains phosphate in iron-oxide complexes. However, only oxygen and not nitrate was effective in decreasing sediment ammonia release, likely by enhancing biological nitrification and assimilation in surficial sediments under oxic conditions. A number of in-lake management strategies have been developed to inhibit internal nutrient loading including calcium nitrate addition, aluminum sulfate addition, and oxygenation. In our view, the deliberate addition of nitrate to lakes and reservoirs poses several risks that must be carefully considered when evaluating strategies to control sediment phosphorus release.
The role of river inputs on the hypolimnetic chemistry of a productive reservoir: implications for management of anoxia and total phosphorus internal loadingRafael Marcé; Enrique Moreno-Ostos; Joan ArmengolLake and Reservoir Management1040-23810743-81412412008 87 - 98The role of river inputs on the hypolimnetic chemistry of a productive reservoir: implications for management of anoxia and total phosphorus internal loading The effect of DOC and nitrate river inputs on summer hypolimnetic oxygen and nutrient dynamics in the advective-dominated, canyon-shaped Sau Reservoir (Spain) was investigated using 11 years of monitoring data. River water entering the reservoir during summer was the main driver defining hypolimnetic oxygen and nutrient concentration. Thus, volume-normalized hypolimnetic oxygen concentration was highly correlated with the river DOC, but not significantly correlated with surrogates of the epilimnetic primary production or with in-lake features. Also, the areal extent of anoxia and nitrate concentration controlled total phosphorus content in the hypolimnion, suggesting that the river DOC and nitrate inputs control internal load of phosphorus. Because improvement of the river water quality was the consequence of implementation of advanced wastewater treatment plants in the reservoir watershed, we advocate these solutions to manage reservoir eutrophication problems. Our results should prompt reservoir limnologists to always take into account the probable, direct effect of allochthonous sources in the hypolimnetic oxygen content and nutrient dynamics, especially in human-impacted systems.
Role of land cover and hydrology in determining nutrients in mid-continent reservoirs: implications for nutrient criteria and managementJohn R. Jones; Matthew F. knowlton; Daniel V. ObrechtLake and Reservoir Management1040-23810743-81412412008 1 - 9Role of land cover and hydrology in determining nutrients in mid-continent reservoirs: implications for nutrient criteria and management Effects of nutrient input, hydraulic flushing rate and depth on reservoir nutrients were examined in the mid-continent landscape of the Ozark Highlands and Plains in Missouri and Plains of southern Iowa. Regionally the clear south-to-north increase in reservoir nutrients, amounting to a 4-fold increase in median total phosphorus (TP) and 3-fold increase in median total nitrogen (TN), showed a strong cross-system pattern with cropland cover (a surrogate for nonpoint-source nutrient loss from agricultural watersheds) but not with an index of hydraulic flushing rate. Cropland accounted for variation in TP in the Ozarks (51%) and TN in all 3 regions (Ozarks 58%, Plains 41%, Iowa 27%). Flushing accounted for variation in TP in the Missouri Plains (49%) and Iowa (29%). Our models suggest large-scale nutrient reduction will require massive changes in land cover to reduce nutrient input. In the Missouri Plains, for example, reducing cropland from 60% to 30% reduces TP and TN by only about 20% when other factors are held constant. Hydrology places added limits on reducing reservoir nutrients; consistent with theory, TP values in Missouri Plains reservoirs effectively double between flushing rates of 0.25 and 2 at any given cropland value. Dramatic nutrient reduction in these reservoirs is unlikely, and the influential role of hydraulic flushing adds additional management challenges for compliance with regional nutrient criteria. The analyses suggest hydrology must be considered when setting nutrient criteria, and it would be unreasonable to establish criteria based on water bodies with long retention time and apply them to rapidly flushed lakes.
Drivers of change for lakewater clarityLawrence A. Baker; Johanna E. Schussler; Stephanie A. SnyderLake and Reservoir Management1040-23810743-81412412008 30 - 40Drivers of change for lakewater clarity Lakes in the Upper Midwest have undergone extensive lakeshore development over the past 30 years, raising concerns about eutrophication. We examined 11 case study lakes in Minnesota that had undergone substantial shoreline development over the past 30 years to evaluate drivers of change in clarity. Relationships between current Secchi disk transparency (SDT) and the density of permanent equivalent houses (PEHs) and between change in SDT and change in density of PEHs were not statistically significant. For lakes with large watershed area-to-lake area (WSA: LA) ratios, modeled worst-case scenarios for impacts of shoreline housing show that phosphorus (P) inputs may not be sufficient to reduce SDT. For sensitive lakes, improved P management policies may counteract increased shoreline development, at least in part. For lakes with large WSA:LA ratios, activity outside the shoreline area, particularly agricultural activity, is probably more important than shoreline development in affecting SDT. Although policies considered “lake management” operate at fairly small scales, drivers of change in SDT operate at various temporal and spatial scales, from household to global.
Lake management (muck removal) and hurricane impacts to the trophic state of Lake Tohopekaliga, FloridaMark V. Hoyer; Roger W. Bachmann; Daniel E. Canfield Jr.Lake and Reservoir Management1040-23810743-81412412008 57 - 68Lake management (muck removal) and hurricane impacts to the trophic state of Lake Tohopekaliga, Florida Lake Tohopekaliga is a large (surface area 9,800 ha) and shallow (mean depth 2.1 m) natural lake in central Florida. Cultural eutrophication and lake water level stabilization led to accelerated growth of invasive native and non-native aquatic macrophytes, resulting in the buildup of thick deposits of organic matter along the shoreline. Those shoreline areas were often devoid of oxygen, and the muck buildup filled feeding grounds for wading birds and spawning fish. Muck build up has also reduced aesthetics and boat access. To remove organic accumulation, the lake water level was dropped and heavy equipment was used to scrape the plants and dead organic materials from the underlying sand substrates from more than 1,420 ha of the littoral zone. Most of this material was heaped into large piles in shallow parts of the lake to form 29 artificial islands with basal areas from 0.4 to 3.3 ha each. Our study was designed to determine: (1) amount of nutrients stored in islands relative to annual inflows, (2) nutrient release to the lake from the islands, and (3) changes in lake trophic state due to the muck scraping and construction of the islands. The lake enhancement project was completed in late summer 2004, and the average thickness of organic materials in the scrapped areas was reduced from 46 cm to 1.6 cm, improving access and aesthetics tremendously. The islands stored several times the annual inflow of total phosphorus (TP, 3.1 times) and Total Nitrogen (TN, 6.5 times) and thus could potentially affect the lake's trophic state by leaching nutrients. Our study of water quality in the vicinity of the islands indicates that the islands had no statistically significant impact on the water chemistry of the lake through leaching of nutrients. In the 2 years following the muck removal, substantial increases in average TP (39%), chlorophyll (56%), and color (53%) and a decline in dissolved oxygen (-10%) were found in open water stations. An unintended complication to our experimental design was the occurrence of 3 major hurricanes with high winds and heavy rainfalls that passed over the Lake Tohopekaliga area immediately following the muck removal project. To account for the effects of hurricane activity we examined monthly TP, TN, chlorophyll, Secchi depth data, and quarterly color values measured for 55 relatively small (median surface area 33 ha), nearby lakes. Our sample of 55 nearby lakes showed significant increases in TP (8.2%), TN (4.1%), chlorophyll (20.1%), and water color (23.8%), and decreases in Secchi depth (-8.2%) coinciding with the passage of the hurricanes. Additionally, data from a larger control lake (Kissimmee, surface area 19,800 ha) located 10 km south of Lake Tohopekaliga showed a much larger increase in total phosphorus (66%). Therefore, some or possibly all of the differences we measured before and after scraping could have been the result of low quality water (high nutrients and organic color) flushed into the lake following the heavy rains (93 cm in August and September of 2004) accompanying the storms. The effects of muck removal cannot be completely separated from those of hurricanes because they both occurred at the same time. However, aquatic plant (Florida Department of Environmental Protection) and water chemistry (Florida Fish and Wildlife Conservation Commission) data collected after this project was completed show that submersed aquatic macrophytes in Lake Tohopekaliga have returned and total phosphorus and chlorophyll concentrations are down to levels measured prior to muck scraping and hurricane impacts. Thus, the changes in water chemistry caused by muck removal and/or the hurricanes were relatively short lived (approximately 2 years).
Insights for the structure of a reservoir turbidity model from monitoring and process studiesSteven W. Effler; David M. O'Donnell; David A. Matthews; MaryGail Perkins; Susan M. O'Donnell; Rakesh K. Gelda; Anthony R. Prestigiacomo; Feng Peng; David G. Smith; Andrew P. Bader; James D. MayfieldLake and Reservoir Management1040-23810743-81412412008 69 - 86Insights for the structure of a reservoir turbidity model from monitoring and process studies An array of in situ and laboratory measurements were made and in situ settling velocity experiments were conducted to support identification of model structure features necessary to simulate transient turbidity impacts in Schoharie Reservoir, NY, from runoff events. The program included: (1) extended deployments of recording instruments measuring temperature (T) and specific conductivity (SC) in the primary tributary and the reservoir surface waters; (2) automatic sampling of the tributary during runoff events for laboratory turbidity (Tn) measurements; (3) collection of vertically detailed profiles of T, SC, and the beam attenuation coefficient at 660 nm (c660; a surrogate of Tn) at multiple sites along the longitudinal and lateral axes of the reservoir with rapid profiling instrumentation; (4) chemical and morphometric characterizations of individual particles from the tributary and reservoir during dry weather conditions and for a runoff event with scanning electron microscopy coupled with automated image analysis and X-ray microanalysis (SAX); and (5) in situ measurements of settling velocity (SV) as a function of particle size with a LISST-ST®. A strong positive relationship between Tn, associated primarily with clay minerals, and tributary flow (Q), and a negative relationship between SC and Q, were reported. The entry of the primary tributary as a plunging turbid density current because of its lower T, and associated spatial and temporal patterns in c660 and SC imparted in the reservoir, were documented for two runoff events. SC was identified as a viable tracer of the movement of density currents in the reservoir, and the internal contribution of resuspension to c660 levels was depicted. The results of SAX analyses demonstrated a substantial fraction (i.e., 30-40%) of the Tn that enters the reservoir from the primary tributary was associated with particles >9.1 μm in diameter that do not contribute to Tn levels in the lacustrine portions of the reservoir. Higher SV values were observed for larger particles, but were much lower than Stokes Law conditions, suggesting that they existed as aggregates. The monitoring and SV experiment results were considered within the context of the structural needs of turbidity models, for two levels of complexity, to simulate the transient impacts of runoff events on the reservoir. A two- or three-dimensional transport submodel will be necessary to represent spatial patterns, and a kinetics submodel will need to represent (either implicitly or explicitly) size dependent settling, particle coagulation, and sediment resus-pension.
Application of a nutrient-saturation concept to the control of algal growth in lakesWilliam M. Lewis Jr.; James F. Saunders III; James H. McCutchan Jr.Lake and Reservoir Management1040-23810743-81412412008 41 - 46Application of a nutrient-saturation concept to the control of algal growth in lakes Either phosphorus or nitrogen can be responsible for nutrient limitation of algae in lakes. Nitrogen limitation can be defeated by heterocystous cyanobacteria through nitrogen fixation, but no comparable mechanism exists for P. Therefore, P is considered the predominant factor limiting phytoplankton biomass in lakes. Even so, increasing numbers of studies show that many lakes are limited by N deficiency because heterocystous cyanobacteria do not become sufficiently abundant to offset N deficiency. Where N limitation prevails, P control over phytoplankton populations can be achieved only if P concentrations are first reduced to a saturation threshold that is determined by the amount of available N. The extent of this reduction, which will typically occur without any suppression of phytoplankton biomass, can be estimated from nutrient chemistry, nutrient enrichment experiments, and information on the stoi-chiometry of phytoplankton, as illustrated with data for a Colorado reservoir in which a reduction of N of about 50% would be necessary to induce P limitation. Analysis based on stoichiometry could allow managers of water quality in lakes to anticipate the implications of N limitation for P-based management of water quality.
Watershed management in north Florida: public knowledge, attitudes and information needsMallory M. McDuff; Gary S. Appelson; Susan K. Jacobson; Glenn D. IsraelLake and Reservoir Management1040-23810743-81412412008 47 - 56Watershed management in north Florida: public knowledge, attitudes and information needs Water management policies in Florida emphasize the need for public involvement in managing watersheds, yet little is known about the environmental literacy of key stakeholders - nearby residents and recreational user groups. A mail survey was conducted to assess public environmental knowledge, attitudes, and information needs about watershed management based on a stratified random sample of 700 households in the 1683-km2 Orange Creek Basin in Florida. Most respondents had limited knowledge of the local environment and limited awareness of the local watershed as a landscape feature. Consumptive resource-users (e.g., anglers and hunters) had more knowledge of surface water features than non-consumptive users or non-users. Respondents generally held positive attitudes toward overall ecosystem management objectives. Attitudes toward specific management activities, such as aquatic plant control to improve boating access, differed among groups. Most respondents wanted to learn more about local ecology and preferred to obtain information about the local environment from television, newspapers, and direct mail. Consumptive users preferred to receive information from fish camps and sporting clubs, while non-consumptive users preferred to receive information from nature parks. On-site interpretive programming is needed throughout the basin, along with mass media outreach, to increase public knowledge of and support for sustainable watershed management.
Decline of springtime abundance of the pileworm Neanthes succinea in relation to hydrographic conditions at the Salton Sea, CaliforniaDeborah M. Dexter; Joan S. Dainer; Paul M. Detwiler; Marie F. Moreau; Stuart H. HurlbertLake and Reservoir Management1040-23810743-81412352007 570 - 581Decline of springtime abundance of the pileworm Neanthes succinea in relation to hydrographic conditions at the Salton Sea, California The Salton Sea is the largest lake in California, and its most abundant macroinvertebrate is the pileworm (Neanthes succinea: Polychaeta). This is a major dietary item for three of the four most abundant fish species in the lake, and for at least one waterbird, the eared grebe (Podiceps nigricollis). Pileworm abundance in April 2004 was monitored at depths of 2, 6 and 10 m on seven transects distributed around the perimeter of the lake. Temperature and oxygen showed marked stratification with depth. Densities were compared to those observed in April 1999. Abundances at 2 m stations were similar to those in 1999; however, densities were greatly reduced at 6 and 10 m stations compared to 1999. The development of hypoxic or anoxic bottom conditions apparently occurred earlier in the spring in 2004 than in 1999. This was the most likely cause for the low densities at 6 and 10 m. Worm densities were higher at sites with coarser sediments (sand and/or barnacle shell debris), and lowest at 2 m sites near or downstream of freshwater inflows and at 10 m where near anoxic conditions prevailed. In March 2005, a sampling of 74 stations at depths ranging from 1 m to 10 m all around the perimeter of the lake found only a single pileworm. It was evident that the lake had just turned over and that sulfide levels were very high and had probably killed off most pileworms and many other organisms as well.
Selenium, arsenic, DDT and other contaminants in four fish species in the Salton Sea, California, their temporal trends, and their potential impact on human consumers and wildlifeMarie F. Moreau; Janie Surico-Bennett; Marie Vicario-Fisher; Russell Gerads; Richard M. Gersberg; Stuart H. HurlbertLake and Reservoir Management1040-23810743-81412352007 536 - 569Selenium, arsenic, DDT and other contaminants in four fish species in the Salton Sea, California, their temporal trends, and their potential impact on human consumers and wildlife A summary of all existing information gathered since 1980 on contaminants in bairdiella (Bairdiella icistia), orangemouth corvina (Cynoscion xanthulus), and sargo (Anisotremus davidsonii) living in the Salton Sea is presented. Comparisons are made with an earlier analysis of contaminants in tilapia (Oreochromis mossambicus x O. urolepis hornorum hybrid). Risks are assessed for humans and piscivorous birds consuming these fish and for the health of the fish populations themselves. Of the 17 trace elements, 42 organic pesticides and 48 polychlorinated biphenyls (PCBs) sampled in whole-body and fillet samples of fish collected from the Salton Sea, only arsenic (As), selenium (Se), total DDT (tDDT), and total PCBs (tPCBs) were determined to be of potential concern for the health of human consumers. Recent average concentrations of total As in fillet tissue are 1.3 μg g-1 wet weight (ww) for bairdiella and 1.2 μg g-1 ww for corvina and tilapia, respectively, with the inorganic As fraction representing 0.3-0.4 percent of total As. Based on U.S. Environmental Protection Agency (U.S.EPA) guidelines, these levels do not pose a threat of non-cancer adverse health effects in anglers, but consumption of 360 g (13 oz) of bairdiella, 650 g (23 oz) of corvina, or 540 g (19 oz) of tilapia per week for 70 years would increase the upper bound cancer risk by 1 per 100,000 consumers exposed. Between 1997 and 2002, total As levels in these three species increased an average of ~22 percent per year. Recent geometric mean Se concentrations were 2.9, 2.8, 2.2 and 1.7 μg g-1 ww in fillet tissues of bairdiella, corvina, sargo, and tilapia, respectively. These levels were not found to present unacceptable risk for adverse health effects for adult anglers consuming up to 492 g (17 oz) of bairdiella, 571 g (20 oz) of corvina, 754 g (27 oz) of sargo, or 1000 g (35 oz) of tilapia per week, even when additional intakes of Se from other food items are taken into account. However, during 1997-2000, Se levels in at least corvina and tilapia may have been increasing by an average of ~16 percent per year though they still were lower than 20 years earlier. tDDT (mostly DDE) and PCBs were recently detected in all fish samples. Compared to screening values proposed by the U.S. EPA, these concentrations seem unlikely to cause adverse health effects in anglers consuming less than 70 g of Salton Sea fish per week, but the potential for endocrine disruptive effects warrants further study. tDDT levels have declined by ~50 percent between the early 1980s and the 1990s in bairdiella, corvina and tilapia, paralleling declines in tDDT levels in eggs of fish-eating birds at the Salton Sea. Salton Sea sportfish may be safer for human consumption than was previously thought, but these conclusions are strongly affected by the particular parameter values and assumptions used in risk analyses. Given the strong temporal trends documented for key contaminants in this changing and geochemically unusual lake, risk assessments can also become quickly out of date. Se concentrations may be elevated enough to negatively affect fish health or reproduction as well as the immune systems of piscivorous birds feeding on the fish. Levels of other contaminants in fish were not found to be of concern for birds, but given the paucity of recent analyses on whole fish, additional analyses would be deisrable. Rising salinity caused all these fish species except for tilapia to become extinct in the lake by 2003. If and when fish populations are reestablished, new asessements of contaminant levels and risks should be undertaken immediately.
Ciliate plankton dynamics and survey of ciliate diversity in the Salton Sea, California, 1997-1999Mary A. Tiffany; Brandon K. Swan; Glenn F. Gebler; Jeffrey C. Cole; Maria R. González; Kristen M. Reifel; James M. Watts; Eugene B. Small; Stuart H. HurlbertLake and Reservoir Management1040-23810743-81412352007 606 - 619Ciliate plankton dynamics and survey of ciliate diversity in the Salton Sea, California, 1997-1999 Planktonic ciliates and other protozoa were monitored at mid-lake stations in the saline, polymictic Salton Sea during the period 1997-1999, at approximately two-week intervals. Additionally, in 1999, a survey of ciliate diversity in a variety of microhabitats was undertaken. Ciliates generally comprised < 20 percent of the total zooplankton biovolume, with copepods, rotifers and larvae of a barnacle and polychaete worm making up the rest. However, in early 1999 tintinnids constituted ~40 percent of total zooplankton biovolume, and in September 1998 when metazooplankters were very scarce, ciliates represented nearly 100 percent. An anaerobic ciliate, Sonderia sp., invaded the mid-water column during periods of anoxia and high sulfide levels in 1998 and 1999. Large ciliates, such as Condylostoma spp. and Favella sp. increased in abundance over the three-year period while the smaller forms, mostly scuticociliates, did not. This pattern may be due to a decrease during our study in abundance of the filter-feeding hybrid tilapia (Oreochromis mossambicus x O. urolepis honorum), which may have selectively grazed upon the larger forms. An inverse relationship between copepod abundance and large ciliate abundance suggests copepods also prey on the larger forms. A total of 143 ciliate taxa were found as well as protozoans in other groups such as heliozoans and choanoflagellates.
Phytoplankton dynamics in the Salton Sea, California, 1997–1999Mary A. Tiffany; Maria R. González; Brandon K. Swan; Kristen M. Reifel; James M. Watts; Stuart H. HurlbertLake and Reservoir Management1040-23810743-81412352007 582 - 605Phytoplankton dynamics in the Salton Sea, California, 1997-1999 The dynamics of phytoplankton populations in the Salton Sea were studied over the 3-year period 1997-1999. Dino-flagellates were important components, often contributing over 80% of the total biovolume of cells larger than 5 μm. Gyrodinium uncatenum along with a similar, but rarer species Gyrodinium instriatum, was the most dominant taxon, present year-round, and became especially abundant in spring and summer. Diversity of dinoflagellates was high with three or four species often co-occurring with similar densities. The largest dinoflagellate, Gonyaulax grindleyi (= Protoceratium reticulatum), increased greatly in abundance during 1997-1999. Diatoms co-dominated year round with the colonial araphid Thalassionema sp. also becoming especially abundant in 1999. During the winter mixing period, diatom populations often were dominated by pennate species usually considered benthic, such as Pleurosigma ambrosianum, Ceratoneis closterium and Tryblionella punctata. Cryptomonads, represented by several species, were usually numerous and, although relatively small, constituted as much as 20-30% of total phytoplankton biovolume. A raphidophyte, Chattonella marina, reported to be ichthyotoxic in other locales, was abundant in summer, comprising about a third of total phytoplankton biovolume then and reaching mid-lake densities of nearly 1,500 cells ml-1. Two colonial non-motile green algae were usually present; one of these, Crucigenia rectangularis, increased greatly in density in 1999. A euglenoid, Eutreptia lanowii, was highest in density in summer when it contributed about 5-10% of total biovolume at times after other species were reduced by sulfide events. Filamentous planktonic cyanobacteria were very rare. The increase in large species of phytoplankton over the three-year period coincided with a dramatic decrease in abundance of a planktivorous fish, the Mozambique mouthbrooder (Oreochromis mossambicus x O. urolepis honorum), which likely was responsible for these changes in phytoplankton composition. Phytoplankton biovolume densities and chlorophyll a concentrations each year were highest, 6-16 mm3 l-1 and 30-40 μg 1-1 respectively, in the spring. In summer and early fall, occasional windstorms mixed the water column causing sulfide-laden bottom waters to upwell and strip surface waters of oxygen. Sharp drops in abundance of most phytoplankton species occurred during these events presumably due to poisoning by hydrogen sulfide. Satellite images confirm the presence of large patches of high albedo surface waters at these times, lasting days to over a week, produced by backscattering from abundant crystals of gypsum produced following oxidation of hydrogen sulfide to sulfate.
Stratification, sulfide, worms, and decline of the Eared Grebe (Podiceps nigricollis) at the Salton Sea, CaliforniaThomas W. Anderson; Mary Ann Tiffany; Stuart H. HurlbertLake and Reservoir Management1040-23810743-81412352007 500 - 517Stratification, sulfide, worms, and decline of the Eared Grebe (Podiceps nigricollis) at the Salton Sea, California Over the last half century the Salton Sea has been an important migratory stopover site for the Eared Grebe (Podiceps nigricollis). However, in recent years there have been sporadic mass mortalities (i.e., 150,000 in 1992) and a great reduction in the number of grebes visiting during the winter. We propose that a worsening food supply is causing the decline and that starvation may be a major cause of the unexplained mortalities. While at the Sea, grebes forage almost exclusively on a benthic polychaete, the pileworm (Neanthes succinea). This resident pileworm population has increasingly been subject to periodic crashes driven by exposure to anoxic, sulfide rich, hypolimnetic water following lake mixing events. A set of interlocking mechanisms seem to be operating. These involve, in particular, increasing lake salinity, weather events favoring lake stratification, and booms and busts in tilapia (Oreochromis mossambicus O. urolepis hornorum) and plankton populations, including those of toxic cyanobacteria. In spring, Eared Grebes arrive from the Gulf of California and many arrive in need of food to fuel the remainder of their migration. When pileworms are scarce, many grebes are able to continue on toward their northern breeding grounds, but those that lack sufficient energy stores are forced to stay and may eventually perish. This analysis is surely incomplete, and definitive explanations of the excessive drinking and waterlogged plumage often exhibited by Eared Grebes during mass dieoffs have yet to be found.
Fish and fish-eating birds at the Salton Sea: a century of boom and bustAllen H. Hurlbert; Thomas W. Anderson; Kenneth K. Sturm; Stuart H. HurlbertLake and Reservoir Management1040-23810743-81412352007 469 - 499Fish and fish-eating birds at the Salton Sea: a century of boom and bust We reconstruct historical trends in both fish and fish-eating bird populations at the Salton Sea, California since the Sea's formation in 1905. The fish community has undergone dramatic shifts in composition, from freshwater species present in the initial wash-in to stocked marine species to dominance by an unintentionally introduced cichlid. Historical catch records, creel censuses, and gill-netting studies suggest that total fish biomass in the lake increased dramatically throughout the 1970s, crashed in the late 1980s, recovered in the mid-1990s, and crashed again in the early 2000s. We speculate that crashes in fish populations are primarily due to three physiological stressors—rising salinity, cold winter temperatures, and high sulfide levels and anoxia associated with mixing events. The trends in fish biomass are mirrored in population trends of both breeding and wintering fish-eating birds, as indexed by a number of independent bird surveys. In contrast, most non-piscivorous birds at the Salton Sea show no indication of these temporal dynamics. We discuss possible explanations for the observed trends in fish-eating bird populations, including decline in organochlorine insecticide use and fluctuations in prey abundance at the Salton Sea. Finally, we speculate on the future prospects of both fish and fish-eating birds at the Salton Sea given the environmental challenges the Sea currently faces.
Length-weight relations and growth rates of dominant fishes of the Salton Sea: implications for predation by fish-eating birdsRalf Riedel; Lucille M. Caskey; Stuart H. HurlbertLake and Reservoir Management1040-23810743-81412352007 528 - 535Length-weight relations and growth rates of dominant fishes of the Salton Sea: implications for predation by fish-eating birds The Salton Sea is the largest lake in California. Inflows are primarily from agricultural runoff, which render it eutrophic and able to support extensive fisheries. The lake and its surrounding wetlands are critical links for the Pacific Flyway, providing refuge and food for an extensive and diverse avifauna. We document fish size distributions, body shapes and growth rates and consider how they determine availability of fish to birds. Tilapia (Oreochromis mossambicus x O. urolepis hornorum) is the most important resource for fish-eating birds. Tilapia grow fast to a size that is readily handled by large birds and are the most abundant fish in the lake. Bairdiella (Bairdiella icistia) grow to a smaller size over a longer period. Corvina (Cynoscion xanthulus), sargo (Anisotremus davidsoni), and shad (Dorosoma cepedianum) are less important for fish-eating birds because they quickly grow to sizes outside bird handling capabilities (corvina) or are not readily catchable and currently of low abundance (shad and sargo). Shape, in particular girth, determines the weight of the largest individual fish that a bird can handle; a slender 1,000 g corvina, for example, being more easily ingested than a deeper-bodied 1,000 g tilapia. Shape, however, is of secondary importance to growth rate in determining importance of a fish species in a bird's diet. Predation by corvina on tilapia and other smaller species may have historically played a large role in determining availability of fish to fish-eating birds.
Coping with multiple stressors: physiological mechanisms and strategies in fishes of the Salton SeaBrian A. Sardella; Victoria Matey; Colin J. BraunerLake and Reservoir Management1040-23810743-81412352007 518 - 527Coping with multiple stressors: physiological mechanisms and strategies in fishes of the Salton Sea Saline lakes are found around the world, typically within inland drainage basins that lack outflow. While fish species in these lakes are not numerous, the Salton Sea in southeastern California, USA, supports several species and a substantial recreational fishery. The Salton Sea was formed in 1905, and since its formation, the salinity has varied greatly, and is currently approaching 44 g/l. The Salton Sea presents several environmental challenges to fishes that inhabit it, especially high salinity, large variations in temperature, and high levels of calcium and sulphate. Studies investigating the osmoregulatory ability of the California Mozambique tilapia (Oreochromis mossambicus x O. urolepis hornorum), the dominant species in the Salton Sea, indicate that they can tolerate salinities up to 65 g/l at 25 °C with minimal effects on osmoregulatory status. However, a reduction in temperature to 15 °C or an increase to 35 °C (both within the range of temperature observed in the Salton Sea) greatly reduce the salinity tolerance of this species. These data indicate that the seasonal winter kills of California Mozambique tilapia are likely associated with a direct effect of temperature on salinity tolerance at the current salinity of the Salton Sea. In this review we explore these environmental stressors and their effects on fish, particularly within the context of the Salton Sea fishery, and discuss how euryhalinity may give tilapia an advantage over the other Salton Sea species with respect to surviving the dynamic environment.
Dramatic blooms of Prymnesium sp. (Prymnesiophyceae) and Alexandrium margalefii (Dinophyceae) in the Salton Sea, CaliforniaMary Ann Tiffany; Jennifer Wolny; Matthew Garrett; Karen Steidinger; Stuart H. HurlbertLake and Reservoir Management1040-23810743-81412352007 620 - 629Dramatic blooms of Prymnesium sp. (Prymnesiophyceae) and Alexandrium margalefii (Dinophyceae) in the Salton Sea, California In early 2006, unusual algal blooms of two species occurred in the Salton Sea, a large salt lake in southern California. In mid-January local residents reported bioluminescence in the Sea. Starting in February, large rafts of long-lasting foam, also bioluminescent, were observed as well. Microscopy investigations on water and sediment samples collected in March showed the marine dinoflagellate, Alexandrium margalefii, and the prymnesiophyte, Prymnesium sp., both previously unreported in the Salton Sea, to be abundant. Bioluminescence and foam production continued through March. Other dinoflagellate species, recorded during earlier studies, were rare or not detected during these blooms. Despite the fact that many Alexandrium species are known paralytic shellfish poison (PSP) producers, preliminary saxitoxin tests on this population of A. margalefii were negative. Previous reports on A. margalefii do not mention bioluminescence. It appears that the foam was caused by the Prymnesium sp. bloom, probably via protein-rich exudates and lysis of other algal cells, and its glow was due to entrained A. margalefii. This is the first report of A. margalefii in U.S. waters and the first report of it in a lake.
History of eutrophic lake rehabilitation in North America with arguments for including social sciences in the paradigmG. Dennis CookeLake and Reservoir Management1040-23810743-81412342007 323 - 329History of eutrophic lake rehabilitation in North America with arguments for including social sciences in the paradigm The brief history of management and rehabilitation of eutrophic lakes and reservoirs in North America has gone in 4 directions: (1) solving the limiting nutrient controversy; (2) testing in-lake and watershed rehabilitation methods; (3) examining the roles of biology in determining lake trophic state; and (4) involving lake users and owners in lake research and management. Two major outcomes have been reached: (1) a great increase in understanding of eutrophication, its impacts on humans, and its solutions; and (2) major developments in understanding lake and reservoir ecology through a holistic rather than reductionist research model. Diversion and/or control of point and nonpoint sources of nutrients, silt, and organic matter, including internal nutrient recycling, were shown as necessary to lake improvement, but eutrophication problems often continue or return because social, political, and economic forces can thwart treatment effectiveness and longevity. An example is the “American Diet” that drives agricultural pollution of freshwater. The lake management and rehabilitation process should incorporate social scientists into its paradigm so that we can learn how to encourage humans to make choices and have behaviors better suited to successful longterm lake protection and management.
PrefaceRichard C. LathropLake and Reservoir Management1040-23810743-81412342007 321 - 322Preface
Perspectives on the eutrophication of the Yahara lakesRichard C. LathropLake and Reservoir Management1040-23810743-81412342007 345 - 365Perspectives on the eutrophication of the Yahara lakes Eutrophication of the four Yahara lakes—Mendota, Monona, Waubesa, and Kegonsa—near Madison, Wisconsin, has been dramatic since the mid-1800s. For Lake Mendota, the erosion of sediments from higher water levels established by the damming of the lake's outlet, plus the agricultural expansion of its watershed, resulted in blue-green algal growths. These impacts, however, were dwarfed by water quality problems stemming from Madison's wastewater inputs that directly entered Lake Monona from the late 1800s through 1936, and then Lake Waubesa until 1958. Blue-green algal blooms were so bad in the lower Yahara lakes that the Madison Public Health Department conducted major copper sulfate treatments during 1925-1954. During the wastewater input years, inorganic nitrogen (N) and especially dissolved reactive phosphorus (DRP) concentrations in the surface waters were very high (particularly in Waubesa and Kegonsa), indicating neither nutrient was limiting algal growth. No P legacy from the wastewater inputs was found in Waubesa and Kegonsa's sediments; minimal P-binding potential due to low iron (Fe) availability is the hypothesized reason. Mendota's algal blooms were not a problem until the mid-1940s when wastewater inputs from upstream communities increased as well as the agricultural use of N and P fertilizers. This increase in eutrophication symptoms coincided with an increase in indices of DRP and inorganic N concentrations in the lake. After wastewater diversion in 1971, blue-green algal blooms persisted in Lake Mendota, and the onus of the problem shifted to agricultural and urban nonpoint source pollution. While much progress has been made in recent years to control these pollution sources to Mendota, manure runoff during late winter continues as a management problem. As evidence, P loadings during January to March constituted 48% of total loadings measured for 1990-2006 in the Yahara River subwatershed. Much of this runoff P was dissolved and not associated with high sediment loads, whereas during other months, more of the runoff P was bound to sediments that could settle out in lower stream reaches prior to entering the lake. However, low P-binding potential of recently deposited sediments in Mendota along with signs of water quality improvements following periods of drought indicate the lake could respond rapidly to nutrient input reductions. Finally, DRP and inorganic N concentrations since 1980 have indicated that algal growth in the Yahara lakes during July-August may have been limited by not only P, but N (especially in the lower Yahara lakes). Aggressive programs to reduce inputs from both nutrients will be important to prevent scum-forming blue-green algal blooms and filamentous algal growths that could become problematic once zebra mussels become established in the Yahara lakes.
Perceived environmental quality and place attachment in North American and European temperate lake districtsRichard C. Stedman; Richard C. Lathrop; Bev Clark; Jolanta Ejsmont-Karabin; Peter Kasprzak; Kurt Nielsen; Dick Osgood; Maria Powell; Anne-Mari Ventelä; Katherine E. Webster; Anna ZhukovaLake and Reservoir Management1040-23810743-81412342007 330 - 344Perceived environmental quality and place attachment in North American and European temperate lake districts Sense of place, or the meanings and attachments held for settings, continues to emerge as an important factor in environmental management. Previous research in a lake-rich setting in northern Wisconsin, USA, demonstrated that attachment to lakes is based in part on the perceived water quality and perceptions of social conflict. This research explores how these findings are similar or different across sites with very different ecological and social characteristics. To explore these cross-site similarities and differences, a social science survey was implemented in 10 lake districts (total n = 2,278 respondents), including 5 sites in North America and 5 in Europe. These sites share several commonalities: they all lie at fairly similar latitudes in the Northern Hemisphere, and they are all regions relatively rich in lake resources. The results demonstrate the myriad commonalities and contrasts in behaviors, environmental perceptions, and place attachment across sites.
Sulfide irruptions and gypsum blooms in the Salton Sea as detected by satellite imagery, 1979–2006Mary A. Tiffany; Susan L. Ustin; Stuart H. HurlbertLake and Reservoir Management1040-23810743-81412352007 637 - 652Sulfide irruptions and gypsum blooms in the Salton Sea as detected by satellite imagery, 1979-2006 Bright pale-green surface waters, locally called “green tides,” are visible to the naked eye and satellite sensors in patches at the Salton Sea, usually between May and November. These were studied using satellite remote sensing and by direct sampling. Algal blooms are ruled out as a cause as phytoplankton abundance, and chlorophyll concentrations were lower within the patches than in surrounding areas. The presence of abundant microscopic gypsum (CaSO4·2H2O) crystals in surface waters suggests that scattering from this precipitating salt produces the intense signals. Biogeochemical factors include: the decomposition of organic matter, resultant anoxia and production of hydrogen sulfide by sulfate-reducing bacteria at depth, and oxidation back to sulfate and precipitation of gypsum during wind-induced overturn events. Sulfide concentrations following one such event in September 2005 ranged from 0.3 to 2.7 mg 1-1 at the surface and 1.2 to 25 mg 1-1 in bottom waters. Gypsum crystals occurred at densities up to 40,000 ml-1 in surface water on that date, most 20-30 μm in length with some as long as 190 μm. From 1998 to 2006, gypsum blooms appear to have increased in intensity and duration implying an increase in sulfide irruptions and anoxia in surface waters. As much as 97 percent of the lake was affected in early summer of 2003 and 75-80 percent in summers of 2005 and 2006. Events lasted for months at a time during these years. This intensification is likely due to the decline in abundance of a planktivorous fish, a hybrid tilapia, the California Mozambique mouthbrooder, leading to increased algal productivity, more severe anoxia and higher levels of dissolved hydrogen sulfide. Gypsum blooms seem to have occurred at least as far back as the 1970s, and are associated with frequent mass mortalities of fish, plankton and benthos.
Diffusive flux of selenium between lake sediment and overlying water: Assessing restoration alternatives for the Salton SeaEarl R. Byron; Harry M. OhlendorfLake and Reservoir Management1040-23810743-81412352007 630 - 636Diffusive flux of selenium between lake sediment and overlying water: Assessing restoration alternatives for the Salton Sea Elevated concentrations of selenium are a concern for humans and wildlife at the Salton Sea, a large salt lake in the desert of southeastern California. As the lake is highly eutrophic and has become too saline for most fish, various restoration alternatives have been proposed. These would alter the water quality, volume, depth, and surface area of the Salton Sea and possibly create new aquatic habitats. Such changes are likely to alter conditions at the sediment-water interface that could influence the release or storage of selenium in the surficial, most bioavailable layers of lake sediment. A 5-day, 23 factorial laboratory experiment using intact cores of lake sediment with overlying lake water documented effects of dissolved oxygen level (oxic, anoxic) and salinity (2, 20, 35 g/L) on selenium flux. Higher positive flux from sediments into water was observed under oxic conditions and at the lowest salinity values. Selenium flux from the water to the sediment dominated at salinities of 20 and 35 g/L. Dissolved selenite (SeIV) and organic selenium compounds predominated in the overlying water. Results imply that selenium in overlying water is likely to be sequestered to the sediment under future highly saline conditions, as it is today, but may be released into the overlying water if its salinity is very low or if oxygenation is enhanced over current conditions.
Assessment of internal and external lake restoration measures for two Berlin lakesInke Schauser; Ingrid ChorusLake and Reservoir Management1040-23810743-81412342007 366 - 376Assessment of internal and external lake restoration measures for two Berlin lakes Two previously highly eutrophic lakes, Lake Tegel and Schlachtensee in Berlin, Germany, were subjected to similar external but different internal restoration measures during the last 20-25 years. External phosphorus (P) load was reduced in both lakes by P-stripping their main inflows using P-elimination plants; internal P load was treated by aeration in Lake Tegel and by hypolimnetic withdrawal in Schlachtensee. Loads before and after treatment are compared with the targets using the Vollenweider model and a modified One-Box model. The results indicate that external load reduction was the main cause of the pronounced lake water quality improvements. The hypolimnetic withdrawal in Schlachtensee was effective only in the initial years. No significant positive effect can be identified for the aeration of Lake Tegel.
Spatial and temporal patterns of transparency and light attenuation in the Salton Sea, California, 1997–1999Brandon K. Swan; Kristen M. Reifel; Mary Ann Tiffany; James M. Watts; Stuart H. HurlbertLake and Reservoir Management1040-23810743-81412352007 653 - 662Spatial and temporal patterns of transparency and light attenuation in the Salton Sea, California, 1997-1999 Transparency, as measured by Secchi disk depth (SD), and light attenuation (Kd(PAR)) were measured in the Salton Sea in 1997-1999. Linear regression models were used to evaluate the relative importance of phytoplankton and non-phytoplankton substances in determining SD and Kd(PAR). Paired measurements of SD and Kd(PAR) made in 1999 were used to track relative changes in the importance of light absorption and scattering processes. Phytoplankton biomass was a poor predictor of both SD and Kd(PAR) at mid-lake stations, and this is most likely due to high concentrations of non-phytoplankton substances such as inorganic particulate matter in the Salton Sea. During strong windstorms in the warmer part of the year, the upper water column mixes with hydrogen sulfide-laden bottom waters, causing large crashes in plankton populations. This previously reported phenomenon also strongly affects the light regime through the production of gypsum crystals, which scatter large portions of penetrating light. Since a large amount of variation in both SD and Kd(PAR) is not explained by phytoplankton biomass, any use of this relationship to forecast future changes in water clarity through nutrient reductions must be done with caution.
PrefaceLake and Reservoir Management1040-23810743-81412352007467Preface
Danish and other European experiences in managing shallow lakesErik Jeppesen; Martin Søndergaard; Torben L. Lauridsen; Brian Kronvang; Meryem Beklioglu; Eddy Lammens; Henning S. Jensen; Jan Köhler; Anne-Mari Ventelä; Marjo Tarvainen; István TátraiLake and Reservoir Management1040-23810743-81412342007 439 - 451Danish and other European experiences in managing shallow lakes For a century eutrophication has been the most serious environmental threat to lakes in the densely populated or agricultural areas of Europe. During the last decades, however, major efforts have been used to reduce the external nutrient loading, not least from point sources. Despite these comprehensive efforts, lake eutrophication remains a major problem. Today, the highest pollution input is derived from diffuse sources mainly from agricultural land in lake catchments. We describe the actions taken to reduce the external nutrient loading and the lake responses to these actions as well as the use of additional methods to reinforce recovery, such as biomanipulation. We further discuss resilience and short and long-term responses. We highlight the Danish experiences, but add several examples from restoration measures taken elsewhere in Europe. We also briefly discuss how a potential change in climate may affect lake responses to diminished nutrient loading.
Perspectives on the long-term dynamics of lakes in the landscapeJohn J. MagnusonLake and Reservoir Management1040-23810743-81412342007 452 - 456Perspectives on the long-term dynamics of lakes in the landscape Lakes are valued as a part of our “sense of place” at a very local and personal level. Yet protecting a treasured lake from unwanted change increasingly requires that we address long-term drivers acting over broad spatial scales. Global climate change and invasion of exotics, for examples, cannot be dealt with efficiently or even at all at an individual lake scale. Protecting our lake requires regional and global advocacy and action. When we do not act at these longer and broader scales we are often beset with surprises, live with problems not of our choosing, seek solutions for thousands of lakes one lake at a time, and often must live with or manage the consequences of irreversible changes.
Lakes and society: Mirrors to our past, present and futureBrian MossLake and Reservoir Management1040-23810743-81412342007 457 - 465Lakes and society: Mirrors to our past, present and future Ultimately most things are connected. The lessons we learn from our arts, our literature and our science all reflect an understanding of the human lot. Ecology is concerned with systems that include humans but are dominated by other organisms. Sociology and economics are concerned with systems that include non-human organisms but are dominated by humans. Principles derived from a study of the first, it is argued, can be applied to the second (for they are both manifestations of the same thing) in an attempt to explain why we are failing to move toward a sustainable existence. A range of ideas that have emerged from ecological studies, and particularly the alternative states model of shallow lakes, is used to illuminate the current problems of human societies in relation to the global environment.
Lake responses to long-term hypolimnetic withdrawal treatmentsGertrud K. NürnbergLake and Reservoir Management1040-23810743-81412342007 388 - 409Lake responses to long-term hypolimnetic withdrawal treatments Hypolimnetic withdrawal is an in-lake restoration technique based on the selective discharge of bottom water to enhance the removal of nutrients and electro-chemically reduced substances that build up when the hypolimnion becomes anoxic. Comparison of water quality variables before and during treatment in about 40 European and 8 North American lakes indicates that hypolimnetic withdrawal is an efficient restoration technique in stratified lakes. Water quality improvement was apparent in decreased summer average epilimnetic phosphorus (P) and chlorophyll concentrations, increased Secchi disk transparency, and decreased hypolimnetic phosphorus concentration and anoxia. In particular, summer average phosphorus decreases were significantly correlated with annual water volumes and P masses withdrawn per lake area, indicating the importance of hydrology and timing of the treatment. Observations as well as models revealed that avoiding extreme temperature changes in the water column is critical for a successful application of the technique. The removal of colder bottom water may increase bottom water temperatures, which not only increases sediment release rates and sediment oxygen demand but, more important, may lead to thermal instability, resulting in enhanced entrainment of nutrient-rich hypolimnetic water and increased surface eutrophication. Hypolimnetic withdrawal also improved water quality in man-made lakes with bottom outlets unless too much withdrawal led to thermal instability. It failed to have a positive effect in a shallow oligomictic lake, probably because nutrient export was not much increased. A recognized disadvantage of hypolimnetic withdrawal is its impact on downstream waters, including eutrophication, temperature increase, oxygen depletion, and odor development. In the experiences evaluated, treatment of the withdrawal water ranged from no treatment in older remote applications in the European Alps, to passive treatment in wetlands and settling ponds, and modern waste water technologies in more recent applications. Overall, hypolimnetic withdrawal is an effective low-cost restoration technique to combat and potentially reverse eutrophication in stratified lakes and reservoirs.
Reduction of nutrient loading and biomanipulation as tools in water quality management: Long-term observations on Bautzen Reservoir and Feldberger Haussee (Germany)Peter Kasprzak; Jürgen Benndorf; Thomas Gonsiorczyk; Rainer Koschel; Lothar Krienitz; Thomas Mehner; Stephan Hülsmann; Heinz Schultz; Annekatrin WagnerLake and Reservoir Management1040-23810743-81412342007 410 - 427Reduction of nutrient loading and biomanipulation as tools in water quality management: Long-term observations on Bautzen Reservoir and Feldberger Haussee (Germany) Long-term (1976-1999) biomanipulation in Bautzen Reservoir (BR) revealed that a combination of piscivore stocking and catch restrictions for piscivores led to the desired effects of low planktivorous fish biomass and enhanced biomass of large filter feeders (Daphnia galeata). Despite the hypertrophic status of BR, fisheries management shifted the planktivore-dominated fish community into a piscivore-dominated community. High winter (Jan-Mar) Daphnia biomass was a sensitive indicator of reduced planktivory. Although edible phytoplankton was suppressed by elevated Daphnia biomass, mean seasonal (May-Oct) total phytoplankton biomass remained unchanged due to growth of large inedible algae and cyanobacteria. Inedible and total phytoplankton biomass was primarily controlled by phosphorus availability. However, during clear water periods a reduction of total phytoplankton was achieved with drastically increased Secchi readings. In Feldberger Haussee (FH), despite intensive long-term manual removal of cyprinids (1985-2002) and stocking of piscivorous fish (1988-2002), biomanipulation only had restricted, delayed, or transient effects on the ecosystem. Mean proportion of piscivores within total yield increased but was below 20% in most years. Planktivore cyprinid yields dropped until 1990 and remained constant thereafter. Daphnia biomass slightly increased after biomanipulation became effective (1987-1989) but declined to pre-biomanipulation levels later in the experiment (1996-2005). Beginning in 1997, both edible and inedible phytoplankton biomass started to decrease. Finally, when biomanipulation had been implemented after a delay of 8 years water clarity increased significantly. Although external loading reductions and biomanipulation in both lakes resulted in moderate phytoplankton biomass reduction and Secchi depth enhancement, the reasons for the observed changes were different. Even though strong cascading effects were detected at the top of the food web in BR, the trophic cascade was largely decoupled between phyto- and zooplankton. External plus internal phosphorus loading still exceeded a critical threshold below which a top-down-induced indirect effect of phosphorus sedimentation and finally limitation could have reduced phytoplankton biomass. In constrast to BR, the critical phosphorus loading threshold in FH has probably been approached. Nonetheless, cascading effects were weak due to insufficient reduction of planktivorous cyprinids. Improved water quality was primarily a result of resource-related effects. Thus, the 2 long-term experiments reveal that (1) biomanipulation cannot be applied successfully without reducing nutrient loading below a critical threshold (BR), and (2) for successful biomanipulation, 30-40% piscivores within total fish standing stocks are required (BR and FH). Without optimum piscivory, manual removal of planktivores will hardly produce sustained cascading effects (FH).
Long-term management of Pyhäjärvi (southwest Finland): eutrophication, restoration – recovery?Anne-Mari Ventelä; Marjo Tarvainen; Harri Helminen; Jouko SarvalaLake and Reservoir Management1040-23810743-81412342007 428 - 438Long-term management of Pyhjrvi (southwest Finland): eutrophication, restoration - recovery? Pyhjrvi, located in the centre of an intensive agricultural area in southwest Finland, is an example of a lake suffering from eutrophication. The lake has been intensively studied for decades and was the object of comprehensive restoration activities both in the catchment and in the lake since the 1990s. During the last 20 years the quality and general usability of water in Pyhjrvi has deteriorated due to increased algal blooms but has shown some signs of recovery during recent years. These changes have been driven by both a variety of human activities and natural climate related factors such as dry years. Pyhjrvi has been the object of intensive biomanipulation for decades, carried out by commercial fishermen, whose annual harvest rate approaches the total production of vendace (Coregonus albula), the main planktivore in Pyhjrvi. The restoration project has also subsidized the harvest of commercially unwanted fish since 1995. In 2002-2006, the EU provided funds for this fishing, which was especially intensive in 2002-2004. The main goal of the future management is to maintain and ensure the current levels of moderately low algal biomass considered acceptable by the financiers and local users of the lake. Achieving the level of water quality during the 1980s is not currently realistic due to current intensive agricultural use of the catchment, lack of cost-effective tools for load reduction from the agriculture, and climate change threats.
Assessment of multi-year (1956–2003) hypolimnetic withdrawal from Lake Kortowskie, PolandJulita A. Dunalska; Grzegorz Wiśniewski; Czesław MientkiLake and Reservoir Management1040-23810743-81412342007 377 - 387Assessment of multi-year (1956-2003) hypolimnetic withdrawal from Lake Kortowskie, Poland Hypolimnetic withdrawal as a restoration method comprises the withdrawal of the nutrient-rich hypolimnion by a pipe directly to the outlet, thus replacing the surface outflow. The method was first applied to Lake Kortowskie in 1956 and continues today. The direct effects of hypolimnetic withdrawal can be observed in the near-bottom waters during the pipe's operation (May-Sep). The treatment depends on the quantity of water withdrawn by the pipe. A high withdrawal rate increased the rate of hypolimnetic heating, diminished the water mass stability and shortened summer stagnation. Hypolimnetic withdrawal did not improve the oxygen conditions in Lake Kortowskie, although it shortened the duration of the anaerobic conditions near the bottom and diminished the spatial extent of oxygen deficiency. Increased release of phosphorus from the bottom deposits to the near-bottom water and finally the outlet via the withdrawal pipe has been observed, with a consequent impoverishment of the upper sediments. The amount of mineral phosphorus and ammonium nitrogen in the near-bottom water decreased independent of the withdrawn volume. The decrease of phosphorus and nitrogen during the pipe's operation shows that hypolimnetic withdrawal removes nutrients released from bottom deposits so that the lake becomes less enriched in nutrients. Multi-year examination has confirmed that this process is the most positive feature of this restoration method. The restoration can be optimized by maximizing nutrient export and withdrawing throughout the summer stagnation (particularly in August and September), when nutrient concentrations near the bottom are maximal
Assessing Fish Populations in Remote Subarctic Lakes Using HydroacousticsKyle J. Hartman; F. Joseph MargrafLake and Reservoir Management1040-23810743-81412332007 211 - 218Assessing Fish Populations in Remote Subarctic Lakes Using Hydroacoustics High latitudes of North America and Asia have many unstudied small lakes. The remoteness of these lakes presents a challenge to biologists who manage these systems. At Togiak National Wildlife Refuge in Alaska we evaluated the use of mobile hydroacoustic surveys as a tool for assessing unstudied lakes and setting priorities for further study. We sampled 50-ha Hole Lake in July 2002 with a 120-kHz split-beam hydroacoustic system, completing four surveys at different times throughout daylight and darkness. Despite day-night changes in distribution of fishes in the lake we found no significant differences in relative biomass, density, or in the detection of larger fish targets that may be of importance from a fisheries management perspective. However, between-transect variability in acoustic measures was high and may have masked the ability to detect these changes. Nonetheless, a simple design bisecting the study lake that was completed in 25 min was capable of detecting fish populations of potential interest to fisheries managers. We suggest a simple design (bisecting the lake) for scanning such lakes for the presence of fish populations of interest in these remote areas.
Controls on algal abundance in a eutrophic river with varying degrees of impoundment (Kalamazoo River, Michigan, USA)Nicole J. Reid; Stephen K. HamiltonLake and Reservoir Management1040-23810743-81412332007 219 - 230Controls on algal abundance in a eutrophic river with varying degrees of impoundment (Kalamazoo River, Michigan, USA) This study examined how nutrients and hydraulic flushing interact to regulate growth of phytoplankton in the Kalamazoo River (Michigan, USA), which has seven reservoirs with summer residence times ranging from <1 to 12 days. The largest reservoir, Lake Allegan, suffers from eutrophication and resultant impairments of beneficial uses, problems being addressed by a TMDL focused on control of phosphorus. Water residence time was the most important control on algal growth in the various impoundments, including Lake Allegan, where residence time remained <12 days through the summer. Based on longitudinal surveys, free-flowing river reaches appeared to remove phyto-plankton, whereas a series of old decommissioned dams above Lake Allegan evidently contributed to algal biomass accumulation in the river. Nutrient concentrations were generally high throughout the river system; thus, algal growth may not be nutrient-limited at present. Phytoplankton in the two largest reservoirs was dominated by diatoms and green algae during late summer, despite nutrient concentrations that would tend to favor cyanobacteria in lakes. The relative availability of phosphorus (P), nitrogen (N), and silicon (Si) can indicate how algal growth may respond if nutrient concentrations were to decrease in the future. Nutrient ratios suggest that N and Si could be important in addition to P, depending on the reservoir and the season. In reservoirs with short water residence times, strategies to control eutrophication by reducing phosphorus loading may not yield results as readily as they do in lakes; hydraulic flushing, other nutrients, and upstream impoundments must also be considered.
Improved estimation of wetland cover in the western Canadian boreal forestKendra Couling; Ellie E. Prepas; Daniel W. SmithLake and Reservoir Management1040-23810743-81412332007 245 - 254Improved estimation of wetland cover in the western Canadian boreal forest The Alberta Wetland Inventory (AWI), which is used in a variety of applications across the province to estimate wetland cover from aerial photographs, detected only 34% of confirmed wetland field plots in boreal forest watersheds in the Swan Hills of Alberta. Given the association between wetland cover and runoff and surface water chemistry in western Canadian boreal forest (Boreal Plain) watersheds, accurate quantification of wetland cover is critical to efforts to model hydrologic processes and water quality. Therefore, as a component of the Forest Watershed and Riparian Disturbance (FORWARD) Project, the Wetland Inventory and Identification Tool (WIIT) was developed and successfully detected 81% of the wetland field plots. Application of both models across a variety of landscapes in the boreal forest of Alberta demonstrated that wetland cover estimates were 1.5 times higher with the new WIIT model than with AWI. Also, WIIT identified polygons that were both smaller and contained taller trees than those identified by AWI, indicating that this computer model may be more effective than wetland identification methods that use only aerial photography. Results of this study show that careful interpretation of aerial photographs at the 1:15,000 scale, coupled with ground truthing and computer models, can provide an accurate means of identifying wetlands on Boreal Plain landscapes.
Turbidity and suspended solids levels and loads in a sediment enriched stream: implications for impacted lotic and lentic ecosystemsAnthony R. Prestigiacomo; Steven W. Effler; David O'Donnell; James M. Hassett; Edward M. Michalenko; Zhongping Lee; Alan WeidemannLake and Reservoir Management1040-23810743-81412332007 231 - 244Turbidity and suspended solids levels and loads in a sediment enriched stream: implications for impacted lotic and lentic ecosystems The implementation of an automated stream monitoring unit that features four probe-based turbidity (Tn) measurements per hour and the capability to collect frequent (e.g., hourly) samples for total suspended solids (TSS) analyses during runoff events to assess the dynamics of Tn, TSS and corresponding loads in sediment-rich Onondaga Creek, NY, was documented. Major increases in both Tn (maximum of 3,500 NTU) and TSS (maximum of 1630 mg/L) were reported for the stream during runoff events. Relationships between Tn, TSS and stream flow (Q) were developed and applied to support estimates of TSS loading (TSSL). Tn was demonstrated to be a better predictor of TSS than Q, supporting the use of the frequent field Tn measurements to estimate TSSL. During the year of intensive monitoring, 65% of the TSSL was delivered during the six largest runoff events that represented 18% of the annual flow. The high Tn levels and extensive in-stream deposition have negatively impacted the stream's biota and the esthetics of a downstream harbor. Onondaga Creek is reported to be the dominant allochthonous source of inorganic particulate material to downstream Onondaga Lake. These sediment inputs have important implications for the lake, within the context of two on-going rehabilitation programs aimed at contaminated lake sediments and the effects of extreme cultural eutrophication, by contributing substantially to sedimentation and turbidity. A satellite image documented the occurrence of a conspicuous turbidity plume that emanated from Onondaga Creek following a minor runoff event, suggesting such an effect is common and that related impacts are not spatially uniform.
Evaluation of aquatic macrophyte community response to island construction in the Upper Mississippi RiverHeidi A. Langrehr; Brian R. Gray; Jeffrey A. JanvrinLake and Reservoir Management1040-23810743-81412332007 313 - 320Evaluation of aquatic macrophyte community response to island construction in the Upper Mississippi River Impounding large rivers has often led to reductions in aquatic habitat diversity over time. One approach used to restore habitat on the Upper Mississippi River is island construction. A specific purpose of island construction is to increase the growth and diversity of aquatic macrophytes. We addressed whether this purpose was met for islands constructed in a reach of the Upper Mississippi River. Aquatic macrophyte levels and richness around 2 constructed island complexes were compared with those in open water reference areas in 1998 and 2000. These data suggest that macrophyte levels increased in the construction area relative to the reference area for the second but not the first island complex. Findings were similar for both percent frequency of occurrence and richness index models. These differences in response are attributed to the differing maturities of the 2 island complexes. The first complex was completed 6 years prior to the initiation of aquatic macrophyte sampling, whereas sampling began midway through the construction phase of the second complex. The response of aquatic macrophytes in the first island complex may have stabilized prior to sampling, whereas aquatic macrophyte responses to construction of the second island complex were partially captured during the sampling period. These findings suggest that island construction positively influences aquatic macrophyte levels in impounded reaches of large rivers.
Application of a steady-state nutrient model and inferences for load reduction strategy in two public water supply reservoirs in eastern ConnecticutFarhad Nadim; Amvrossios C. Bagtzoglou; George E. Hoag; Fred L. Ogden; Glenn S. Warner; David M. SoballeLake and Reservoir Management1040-23810743-81412332007 264 - 278Application of a steady-state nutrient model and inferences for load reduction strategy in two public water supply reservoirs in eastern Connecticut Mansfield Hollow Lake (MHL) and Willimantic Reservoir (WR) are two reservoir lakes located in eastern Connecticut in the northeastern United States. MHL formed behind the Mansfield Hollow Dam constructed by the U.S. Army Corps of Engineers in 1952 and is primarily fed by the Fenton, Mount Hope and Natchaug Rivers. The WR lies approximately 1-km downstream from the Mansfield Hollow Dam. Total dissolved nitrogen, phosphorus and chlorophyll a measurements indicate the water bodies could be classified as borderline mesotrophic/eutrophic. A steady-state numerical software package (Bathtub) designed to facilitate application of empirical eutrophication models to morphometrically complex reservoirs was used to determine the trophic status in MHL and WR based on different phosphorus and nitrogen loading budgets. The short hydraulic residence times and rapid flushing rates in MHL and WR are directly related to the flow rates in the streams discharging into MHL. The low flow period could significantly increase the hydraulic residence times of these two reservoirs. Therefore, the sampling design emphasized periods of low flow in late August and early September to assess the impact of nutrient inputs to MHL and WR during dry periods. The results of a low flow sampling period (August 2002) were used to calibrate and test the Bathtub model developed for these water bodies. Application of the Bathtub model to differing flow regimes, notably average flows, suggested that nitrogen or phosphorus could limit the productivity and cause eutrophication in the two lakes. Results of this study indicated that the Bathtub model could be used to predict total nitrogen and total phosphorus concentrations with reasonable accuracy, but it might not be a suitable tool for predicting organic nitrogen or algae in rapidly flushing lake systems. To further investigate and validate the assumptions made in this study, more sampling data are needed, especially during high intensity storm events to investigate possible sources of nutrient flow into the two lake system and further calibrate the Bathtub model for the MHL-WR watershed.
Response of Cylindrospermopsis raciborskii and Pseudanabaena limnetica to a potential biological control agent, bacterium SG-3 (Lysobacter cf. brunescens)Kathryn Wilkinson Flaherty; H. Lynn Walker; Clay H. Britton; Carole A. LembiLake and Reservoir Management1040-23810743-81412332007 255 - 263Response of Cylindrospermopsis raciborskii and Pseudanabaena limnetica to a potential biological control agent, bacterium SG-3 (Lysobacter cf. brunescens) A bacterium (SG-3) was reported by Walker and Higginbotham (2000) to lyse cells of filamentous planktonic species of cyanobacteria such as Anabaena, Oscillatoria and Lyngbya. We tested the efficacy of SG-3 in the laboratory to control Cylindrospermopsis raciborskii, a species with the potential to produce toxins, and Pseudanabaena limnetica, a species that causes taste and odor problems in water. Both were susceptible to SG-3 concentrations of 1.5 107 PFU/mL (PFU = plaque forming units), which was consistent with the concentrations used by Walker and Higginbotham (2000). In tests with a range of SG-3 concentrations (15 to 1.5 107 PFU/mL), cell numbers of the Lake Yale and Lake Griffin (FL) isolates of C. raciborskii in relation to untreated controls were reduced by 89-99% at SG-3 concentrations of 1.5 105 PFU/mL. The Lake Griffin isolate was somewhat more sensitive to SG-3 than the Lake Yale isolate. The calculated EC50 and EC100 for the Lake Griffin strain were 1.2 103 PFU/mL and 3.3 105 PFU/mL, respectively; the calculated EC50 and EC100 for the Lake Yale strain were 6.2 103 PFU/mL and 1.2 106 PFU/mL, respectively. The efficacy of SG-3 was also tested in lake water, which was spiked with the Lake Yale isolate of C. raciborskii; cell counts were reduced from 83 to 95% at SG-3 concentrations of 7.5 106 PFU/mL and higher. SG-3 concentrations greater than those that significantly reduced new cell growth were required to kill the initial populations of the Lake Yale strain present prior to treatment. Pretreatment cell numbers of the C. raciborskii isolates were consistent with those recorded in heavily infested lakes. Therefore, SG-3 at the higher end of the concentration range can kill bloom populations; however, it can also be applied at lower concentrations to act as an algistat on the initial cell populations while preventing additional bloom development, an approach that would avoid potential environmental damage from the cell release of toxins or taste and odor compounds.
Tracking long-term acidification trends in Pockwock Lake (Halifax, Nova Scotia), the water supply for a major eastern Canadian cityAmy E. Tropea; Brian K. Ginn; Brian F. Cumming; John P. SmolLake and Reservoir Management1040-23810743-81412332007 279 - 286Tracking long-term acidification trends in Pockwock Lake (Halifax, Nova Scotia), the water supply for a major eastern Canadian city Pockwock Lake, the drinking water supply for the city of Halifax (Nova Scotia, Canada), has been impacted by the deposition of strongly acidic anions. Because long-term monitoring data are lacking, we used diatom-based paleolimnological techniques to track changes in water quality variables in this important water source. Similar to other acidified lakes in this region, Pockwock Lake has undergone changes in diatom assemblages starting ~1940 with a corresponding lakewater pH decrease of 1.2 units. Before ~1940, Pockwock Lake had a diatom-inferred pH ~6.3 and a diatom assemblage dominated by Cyclotella stelligera and Asterionella ralfsii var. americana (>45 μm). With the onset of acidification, diatom-inferred lakewater pH decreased to ~5.8 and there was a shift to dominance by A. ralfsii var. americana (>45 μm) and Tabellaria flocculosa. A subsequent shift in diatom assemblages and inferred lakewater pH was recorded ~1990 suggesting a decrease in dissolved organic carbon (DOC) and water colour. Since ~1992 Pockwock Lake has undergone further acidification, as evidenced by a shift in the diatom assemblage to dominance by Fragilaria acidobiontica, Eunotia spp., and Frustulia pseudomagaliesmontana. Both diatom-inferred and measured lakewater pH = 5.1 during this time interval. The first (~1940-1992) acidification period followed the trend observed in other humic (high DOC) Nova Scotia lakes, whereas the second (post ~1992) acidification event resulted in a diatom assemblage more common in acidified clearwater (low DOC) lakes. Thus, the acidification signal observed in Pockwock Lake likely indicates a change in diatom assemblage resulting from a loss of DOC, and the sudden drop in diatom-inferred pH suggests that the weak acid buffering system of humic DOC had been exceeded. Further acidification and loss of DOC in this lake has the potential to increase the availability of metals in this important water source.
Response of calcareous Nagawicka Lake, Wisconsin, to changes in phosphorus loadingDale M. Robertson; Herbert S. Garn; William J. RoseLake and Reservoir Management1040-23810743-81412332007 298 - 312Response of calcareous Nagawicka Lake, Wisconsin, to changes in phosphorus loading Nagawicka Lake is a 400-ha, phosphorus (P)-limited, calcareous lake (hardness of 300 mg/L CaCO3) in Wisconsin. Because of concern over potential degradation in water quality associated with urban development in the watershed, a study was conducted to determine the effects of past and future changes in P loading on the lake's water quality through the use of empirical eutrophication models. Six existing empirical P models consistently overestimated total P (TP) concentrations in the lake by a factor of about 2 over a range in external P loading because the models do not account for the unique properties of calcareous lakes: co-precipitation of P with calcite and negligible release of P from the deep sediments. Confirmation of the calcite mechanism was proven by analysis of sediment cores. Once the results were adjusted for the consistent biases, other conventional empirical models fairly accurately predicted the measured chlorophyll a concentrations (CHL) and Secchi depths in the lake. The models, adjusted for the consistent overestimation of TP, were then used to predict the effects of increases and decreases in P loading. Total P and CHL were predicted to decrease or increase by a % similar to the % change in P loading to the lake; however, these relations may become very nonlinear with increases in P loading >100%. Because the natural buffering capacity resists eutrophication caused by P loading, roughly twice the P loading can be permitted in oligotrophic calcareous lakes than in noncalcareous lakes before eutrophication thresholds are exceeded.
Factors affecting the maximum depth of colonization by submersed macrophytes in Florida lakesAlexis J. Caffrey; Mark V. Hoyer; Daniel E. Canfield Jr.Lake and Reservoir Management1040-23810743-81412332007 287 - 297Factors affecting the maximum depth of colonization by submersed macrophytes in Florida lakes In 32 Florida lakes, Secchi depth (SD), light attenuation coefficient measured with a light meter, plant and sediment type, and slope were examined with respect to the maximum depth of plant colonization (MDC). The MDC was shown to be significantly related to light through measurements taken by SD (R2 = 0.46; p < 0.05) and a light meter (R2 = 0.41; p < 0.05). While both light measurements can be used to estimate MDC, SD accounted for more variance in MDC than light attenuation coefficients. Plant type, sediment type and slope did not account for more variance in MDC than light measurements for these Florida lakes. Additional unpublished data from 187 Florida Lakes (Florida LAKEWATCH, 279 lake-years of data) also showed a significant positive relationship between SD and MDC (R2 = 0.68; p < 0.05). The best fit MDC-SD regression line in meters was: log (MDC) = 0.66 log (SD) + 0.31. A maximum MDC line relating MDC to SD in meters was also calculated and was found to be equal to: log (max MDC) = 0.53 log (SD) + 0.59. The maximum MDC line describes light limitation when the MDC response falls on or near the response curve, and when MDC values fall below the line, some other factor likely limits colonization of macrophytes.
Identification of cyanobacterial toxins in Florida's freshwater systemsChristopher D. Williams; Mark T. Aubel; Andrew D. Chapman; Peter E. D'AiutoLake and Reservoir Management1040-23810743-81412322007 144 - 152Identification of cyanobacterial toxins in Florida's freshwater systems Toxigenic cyanobacteria are common components of Florida's surface waters and may pose a threat to their ecology and a risk to human health. The Lake County Water Authority, the Florida Department of Health, the St. Johns River Water Management District, the South Florida Water Management District, and the Lee County Health Department have all recently monitored local waters for cyanotoxins. In 2004, 6 central Florida lakes were sampled monthly for 12 months at centrally located open water sample sites. Toxin data (n = 72 for all toxin analyses) showed that microcystins (0.1-3.6 μg/L) were present in all 12 months; multiple bloom events per lake were observed; bloom concentrations ranged from 5-7,500 μg/L; and blooms occurred throughout the entire year. Cylindrospermopsin, ranging in concentration from 0.05 to 0.2 μg/L, was reported in 22% of all samples analyzed and occurred predominantly between August and December. Anatoxin-a was not reported in 2003/2004 but was identified in 2002/2003 (30%, 0.05-7.0 μg/L). Data from the St. Johns River was similar to that of the central Florida lakes. In general, microcystins ranged between 0.1 and 31 μg/L and were detected in all samples (n = 50), while cylindrospermopsin was observed less frequently (30%, n = 48) and at lower concentrations (0.07-1.6 μg/L). Anatoxin-a was not reported (n = 48). In contrast, the major Microcystis spp. blooms that occurred in the St. Johns, the St. Lucie, and the Caloosahatchee rivers in 2005 were reported to contain relatively high levels of microcystins (rangemax. conc.= 278-5700 μg/L) and persisted for approximately 2 months. Data indicate that cyanotoxin production can be a year-round phenomenon in Florida and can occur at levels that may cause ecological and human health problems.
A preliminary exposure assessment of microcystins from consumption of drinking water in the United StatesAnthony Fristachi; Glenn Rice; Jeffery Steevens; Igor LinkovLake and Reservoir Management1040-23810743-81412322007 203 - 210A preliminary exposure assessment of microcystins from consumption of drinking water in the United States This preliminary human exposure assessment of cyanotoxins from consumption of treated drinking water in the United States is based on reported concentrations of microcystin-LR equivalents, (herein referred to as MC-LR), a cyanotoxin measured in a study of North American drinking waters conducted by the American Water Works Association from June 1996 to January 1998. The sampling protocol resulted in a distribution of MC-LR concentrations in waters that likely overestimates the actual distribution encountered by the exposed population, yielding conservatively biased estimates of exposure. Over a 75-year lifetime, the estimated lifetime average daily dose of MC-LR from the consumption of drinking water was estimated to be 1.7 10-3 μg/kg-day with a standard deviation of 0.02. The 90 and 95 percentile exposure estimates were 1.5 10-3 and 3.9 10-3, respectively. Our results suggest that most individuals are exposed to cyanotoxin levels in finished North American drinking waters that are approximately an order of magnitude lower than the World Health Organization's provisional guideline level of 1 μg/L, which corresponds to approximately 0.04 μg/kg-day.
PrefaceJennifer L. Graham; Ann St. Amand; John R. JonesLake and Reservoir Management1040-23810743-81412322007 iPreface
The occurrence and response to toxic cyanobacteria in the Pacific Northwest, North AmericaJ. M. Jacoby; J. KannLake and Reservoir Management1040-23810743-81412322007 123 - 143The occurrence and response to toxic cyanobacteria in the Pacific Northwest, North America Toxic cyanobacteria are of increasing concern in the Pacific Northwest region of North America. Toxic blooms have been documented in Idaho, northern California, Oregon, Washington, and British Columbia and have caused animal poisonings, lake closures, and public health concerns. Microcystins are the most commonly detected cyanotoxins in this region and have been found at water concentrations from <1 μg/L to 30 mg/L. Anatoxins have also been measured in water bodies throughout the region and have been implicated in the deaths of both domestic and wild animals. Environmental factors associated with the occurrence of toxic blooms have been studied in several western Washington lakes. In these lakes, toxic blooms occurred during conditions of high phosphorus, water temperatures, and water column stability. Migration of cyanobacteria from the sediments contributed to toxic blooms in one of the lakes. Although regulations have not been formally adopted by the states and province in this region, some local jurisdictions use the World Health Organization proposed drinking water guideline of 1 μg/L microcystin-LR to close lakes to recreational use and for drinking water supplies. Recommendations currently advocated by Oregon take into account genera-specific differences, as well as separate, less stringent guidelines for recreational water bodies not used for drinking water.
Cyanobacterial toxins in Canadian freshwaters: A reviewB. G. Kotak; R. W. ZurawellLake and Reservoir Management1040-23810743-81412322007 109 - 122Cyanobacterial toxins in Canadian freshwaters: A review Cyanobacterial toxins are a serious water quality concern in productive water bodies worldwide. Microcystins (MCs), which are hepatotoxins, are prevalent in Canadian freshwaters while the occurrence of neurotoxins anatoxin-a, anatoxin-a(s) and saxitoxin appears to be much less common. Concentrations of microcystin-LR (MCLR), presumed to be the most common of the more than 70 MC analogues, are highly variable in phytoplankton assemblages of lakes and greatly influenced by phytoplankton species composition. The frequency of occurrence and concentrations of MC in lakes in western Canada tend to increase with lake trophic status as well as decreasing N:P ratio. Microcystins accumulate in the aquatic food web through feeding activities of invertebrates (i.e., filter-feeding by clams and grazing by zooplankton and gastropods). Eventual trophic transfer of MC to fish, and resulting mortalities have been documented. Human health may also be at risk. Conventional water treatment may adequately remove low MC concentrations from source water, but can fail to completely remove MCs when initial concentrations are high. To address human health concerns, Health Canada established a drinking water guideline of 1.5 μg/L of MCLR. More recently, it has been suggested that β/N-methylamino-L-alanine (BMAA), a non-protein amino acid produced by many species of cyanobacteria, may cause neuro-degenerative disease, thus representing a significant emerging health issue.
Microcystin distribution in physical size class separations of natural plankton communitiesJennifer L. Graham; John R. JonesLake and Reservoir Management1040-23810743-81412322007 161 - 168Microcystin distribution in physical size class separations of natural plankton communities Phytoplankton communities in 30 northern Missouri and Iowa lakes were physically separated into 5 size classes (>100 μm, 53-100 μm, 35-53 μm, 10-35 μm, 1-10 μm) during 15-21 August 2004 to determine the distribution of microcystin (MC) in size fractionated lake samples and assess how net collections influence estimates of MC concentration. MC was detected in whole water (total) from 83% of lakes sampled, and total MC values ranged from 0.1-7.0 μg/L (mean = 0.8 μg/L). On average, MC in the >100 μm size class comprised ~40% of total MC, while other individual size classes contributed 9-20% to total MC. MC values decreased with size class and were significantly greater in the >100 μm size class (mean = 0.5 μg/L) than the 35-53 μm (mean = 0.1 μg/L), 10-35 μm (mean = 0.0 μg/L), and 1-10 μm (mean = 0.0 μg/L) size classes (p < 0.01). MC values in nets with 100-μm, 53-μm, 35-μm, and 10-μm mesh were cumulatively summed to simulate the potential bias of measuring MC with various size plankton nets. On average, a 100-μm net underestimated total MC by 51%, compared to 37% for a 53-μm net, 28% for a 35-μm net, and 17% for a 10-μm net. While plankton nets consistently underestimated total MC, concentration of algae with net sieves allowed detection of MC at low levels (≤0.01 μg/L); 93% of lakes had detectable levels of MC in concentrated samples. Thus, small mesh plankton nets are an option for documenting MC occurrence, but whole water samples should be collected to characterize total MC concentrations.
The occurrence of cyanobacterial toxins in New York lakes: Lessons from the MERHAB-Lower Great Lakes programGregory L. BoyerLake and Reservoir Management1040-23810743-81412322007 153 - 160The occurrence of cyanobacterial toxins in New York lakes: Lessons from the MERHAB-Lower Great Lakes program New York State is bordered by Lake Erie, Lake Ontario and Lake Champlain, which provide recreational opportunities and drinking water for over 20 million people. Little is known about the occurrence of toxic cyanobacteria in New York waters. In 1999 and 2000, several dogs died from anatoxin-a poisoning after contact with Lake Champlain algae. In response to these events, an intensive field program was initiated to develop and evaluate monitoring methods for detection of cyanobacterial toxins in freshwater systems. This work resulted in the development of a tier-based system for monitoring harmful algal blooms. Between 2000 and 2004, more than 2,000 samples were collected and analyzed for the occurrence of cyanobacterial toxins from sites across New York State. These samples were tested for the hepatotoxic microcystins and cylindrospermopsin as well as the neurotoxins, anatoxin-a, and paralytic shellfish poisons (PSP). A simple extraction procedure using 50% methanol gave >90% recovery of PSP toxins, microcystins, and anatoxin-a from a single sample. This extract was analyzed for cyanobacteria toxins using multiple techniques including ELISA, enzyme inhibition assays, and HPLC with fluorescence, photodiode array, or mass spectrometry detectors. Microcystins were found at >1 μg L-1 in 15% of the samples. Anatoxin-a was found less frequently but was often associated with animal fatalities. The PSP toxins and cylindrospermopsin were found only in rare instances. In some lakes (i.e., Oneida Lake), >50% of the samples tested positive for microcystins. These results suggest that cyanobacterial toxins may be a common event in eutrophic waters, and their occurrence should be a concern for lake managers and public health officials.
First assessment of cyanobacterial blooms and microcystin-LR in the Canadian portion of Lake of the WoodsHuirong Chen; Janice M. Burke; W. Paul Dinsmore; Ellie E. Prepas; Phillip M. FedorakLake and Reservoir Management1040-23810743-81412322007 169 - 178First assessment of cyanobacterial blooms and microcystin-LR in the Canadian portion of Lake of the Woods Cyanobacterial blooms containing the hepatotoxin microcystin-LR (MC-LR) occurred at least once at each of 5 sites sampled in June, July and August 2004 in the Boreal Shield (Ont., Canada) portion of Lake of the Woods. In June, cyanobacteria constituted 3.5-49% (median 25%) of total phytoplankton biomass and consisted largely of Aphanothece spp. (median 98% of total cyanobacterial biomass). In July and August, cyanobacteria comprised 54-98% (median 77%) of total phytoplankton biomass in surface water samples and consisted largely of Aphanizomenon flos-aquae (median 82% of total cyanobacterial biomass). Three species of Anabaena (A. flos-aquae, A. lemmermannii, and A. mendotae), as well as Homeothrix janthina, Pseudanabaena spp., Aphanocapsa spp., and Woronichinia spp. were also present during the study period. Among study sites, total phosphorus concentrations in surface grab samples ranged from 11 to 31 μg/L and were positively associated with total cyanobacterial biomass (r = 0.64, P = 0.01). MC-LR concentrations (μg/g dry weight) in bloom material collected with a 64-μm tow net and analyzed by High Performance Liquid Chromatography were positively related to ammonium concentrations in surface grab samples (r = 0.94, P = 0.001), but not to the total biomass of cyanobacteria or any cyanobacterial taxon. In the isolated Boreal Shield basins of this lake, cyanobacterial blooms and cyanotoxins like MC-LR may have ecological and human health consequences and may be sensitive indicators of human disturbance in the drainage basin.
Efficacy of molecular DNA methods for confirming species identifications on morphologically variable populations of toxin-producing Anabaena (Nostocales)Ann St. Amand; Juli Dyble; Mark Aubel; Andrew Chapman; Joseph EilersLake and Reservoir Management1040-23810743-81412322007 193 - 202Efficacy of molecular DNA methods for confirming species identifications on morphologically variable populations of toxin-producing Anabaena (Nostocales) Algal samples were analyzed from 3 lakes, Crane Prairie Reservoir and Odell Lake in Oregon and an Anonymous North East System, using both standard taxonomic criteria for identification and DNA sequencing techniques. Two toxin-producing Anabaena populations, one with consistent akinete structure and another with variable akinete structure, were investigated. Samples were characterized based on several genetic markers (nifH, cpcBA-IGS, ITS1), toxins (anatoxin-a, saxitoxin, and microcystin) and morphological variation. Taxonomy within the Nostacales is based on vegetative and terminal cell structure, filament type and aggregation, and position and structure of heterocysts and akinetes. Many taxonomists rely heavily on akinete structure for microscopic identification. Identification from material preserved with Lugol's solution is challenging due to the breakup of colonies, cell distortion, and masking of pigment color. Based on morphological variation, the Crane Prairie and Odell populations were identified as A. flos-aquae, A. circinalis, or A. lemmermannii, and toxin analysis detected the presence of microcystin. These populations were most similar to A. lemmermannii (cpcBA-IGS) or Anabaena sp. (ITS1) by DNA sequence analysis. The Anonymous North East System population was identified as A. flos-aquae, A. circinalis or A. spiroides based on morphological variation, and both microcystin and anatoxin-a were detected in these samples. Sequences most similar to A. cylindrica (nifH), A. planktonica (cpcBA-IGS), A. spiroides or Aphanizomenon flos-aquae (ITS1) were identified in the Anonymous North East System samples, but there were no definitive matches. Although molecular methods can be useful tools for confirming identification based on field material, their ability to resolve issues of taxonomic identification are dependent on the comprehensiveness of the sequence database. Taxonomic keys based on cell morphology and identification based on current DNA sequence databases are subject to similar levels of variation and uncertainty.
Eutrophication and cyanobacteria blooms in run-of-river impoundments in North Carolina, U.S.A.Brant W. Touchette; JoAnn M. Burkholder; Elle H. Allen; Jessica L. Alexander; Carol A. Kinder; Cavell Brownie; Jennifer James; Clay H. BrittonLake and Reservoir Management1040-23810743-81412322007 179 - 192Eutrophication and cyanobacteria blooms in run-of-river impoundments in North Carolina, U.S.A. We compared monthly data taken during the dry summer growing season of 2002 in 11 potable water supply reservoirs (19-85 years old based on year filled) within the North Carolina Piedmont, including measures of watershed land use, watershed area, reservoir morphometry (depth, surface area, volume), suspended solids (SS), nutrient concentrations (total nitrogen, TN; total Kjeldahl nitrogen, TKN; nitrate + nitrite, NO3- + NO2-; total phosphorus, TP; total organic carbon), phytoplankton chlorophyll a (chla) concentrations, cyanobacteria assemblages, and microcystin concentrations from monthly data taken during the dry summer 2002 growing season. The reservoirs were considered collectively or as two subgroups by age as “mod.” (moderate age, 19-40 years post-fill, n = 5) and “old” (74-85 yr post-fill, n = 6). The run-of-river impoundments were meso-/eutrophic and turbid (means 25-125 μg TP/L, 410-1,800 μg TN/L, 3-70 μg chla/L and 5.7-41.9 mg SS/L). Under drought conditions in these turbid systems, there was a positive relationship between chla and both TN and TP, supported by correlation analyses and hierarchical ANOVA models. The models also indicated significant positive relationships between TN and TP, and between SS and both TP and TN. Agricultural land use was positively correlated with TKN for the reservoirs considered collectively, and with TN, TKN, TP, and chla in mod. reservoirs. In models considering the reservoirs by age group, TN:TP ratios were significantly lower and NO3- + NO2- was significantly higher in old reservoirs, and these relationships were stronger when reservoir age was used as a linear predictor. Cyanobacteria assemblages in the two reservoir age groups generally were comparable in abundance and species composition, and comprised 60-95% (up to 1.9 106 cells/mL) of the total phytoplankton cell number. Potentially toxic taxa were dominated by Cylindrospermopsis raciborskii and C. philippinensis. Although known microcystin producers were low in abundance, microcystin (< 0.8 μg/L) was detected in most samples. TP and chla were significant predictors of total cyanobacterial abundance. The data suggest that at present these turbid, meso-/eutrophic reservoirs have moderate cyanobacteria abundance and low cyanotoxin (microcystin) levels over the summer growing season, even in low-precipitation seasons that favor cyanobacteria. Accelerated eutrophication from further watershed development is expected to promote increased cyanobacterial abundance and adversely affect the value of these reservoirs as potable water supplies.
Temporal Coherence of Water Quality Variables in a Suite of Missouri ReservoirsMatthew F. Knowlton; John R. JonesLake and Reservoir Management1040-23810743-81412312007 49 - 58Temporal Coherence of Water Quality Variables in a Suite of Missouri Reservoirs A six-year time series of water quality data from four eutrophic prairie reservoirs located in adjacent watersheds in northwest Missouri were analyzed for seasonal patterns and temporal coherence of temperature, dissolved oxygen, transparency, major ions, nutrients, suspended solids and chlorophyll. Water temperature was strongly seasonal as determined by the square of the average correlation of monthly means among years. No other variable was consistently seasonal in all four reservoirs, although two reservoirs exhibited strong seasonality for total and dissolved nitrogen and nitrate. Percent temporal coherence, measured as the square of the correlation between paired reservoir data sets, ranged from ≥98% for water temperature to <15% for chlorophyll. Ionic constituents (especially magnesium and alkalinity) and phosphorus fractions (dissolved, total and soluble reactive) had the strongest coherence (43-66%) averaged across all reservoir pairs. Algal biomass as chlorophyll and volatile solids had the weakest temporal coherence (0-21%). Other variables showed intermediate coherence (≥35%) for one or more reservoir pairs. Coherence strength between reservoirs was related to juxtaposition of catchments and probably reflects catchment-specific features. Temporal synchrony among these reservoirs may reflect a greater influence of external conditions on nutrients than transparency or algal biomass.
Phosphorus and Nitrogen Budgets: Implication of Calcite Precipitation and N:P Ratio in Regulating Chlorophyll a ValuesSabah UI Solim; Ashwani WanganeoLake and Reservoir Management1040-23810743-81412312007 1 - 10Phosphorus and Nitrogen Budgets: Implication of Calcite Precipitation and N:P Ratio in Regulating Chlorophyll a Values Two strong mechanisms, calcite precipitation and chronic low N:P ratio level, are determined to operate in Dal Lake (a shallow Himalayan lake) during the growth period from April to August, and jeopardize the influence of TP and TN loading of 5.89 g/m2 yr-1 and 35.73 g/m2 yr-1, respectively, by restricting the average column chlorophyll a values to 14.1 mg m-3. Biogenic calcite precipitation was brought about during photosynthesis by dense macrophytic populations (average fresh biomass of 3.28 kg/m2) and was aided by increasing temperatures, pH, Saturation index (SI) and flushing rate. During the spring-summer period, from April to August, the average export NP ratio of 9:1 was reduced to 2.1:1 in the ambient system. The nitrogen dependence of algal biomass development was determined for the first time for this lake system by observing a better linear plot between TN loading yr-1 vs. chlorophyll a values (r2 = 0.37, r = 0.61, p = 0.06) instead of TP loading yr-1 vs. chlorophyll a values (r2 = 0.16, r = 0.40, p >0.05). This was further confirmed through two in situ experiments, where chlorophyll a was observed to increase progressively with increasing nitrogen share in NP ratio. Significant linear correlated plots were observed between enrichment medium having NP ratio of 4:1 to 16:1 at an interval of 4 vs. chlorophyll a (r = 0.95, r2 = 0.91 at p<0.05) and enrichment medium having NP ratio of 4:1 to 18:1 at an interval of 2 vs. chlorophyll a (r = 0.73, r2 = 0.53 at p<0.5).
Persistence and Remobilization of Arsenic in Massachusetts (USA) Lakes Treated With Arsenical HerbicidesPaul R. Lattanzi; David B. Senn; Jenny A. Jay; Valerie Monastra; Kathleen M. Regan; John L. DurantLake and Reservoir Management1040-23810743-81412312007 59 - 68Persistence and Remobilization of Arsenic in Massachusetts (USA) Lakes Treated With Arsenical Herbicides From 1953 to 1969 the Commonwealth of Massachusetts funded a program to evaluate the effectiveness of sodium arsenite for treating algae and macrophytes in lakes. It is well known that arsenic (As) is persistent in the environment; however, little work has been done to determine its long-term fate in the treated lakes. Once sodium arsenite is added to lakes, As typically precipitates and accumulates in bottom sediments, but under certain conditions As in surface sediments can be remobilized to the water column under certain conditions. The goals of this study were to determine whether residual As is present in elevated concentrations in the surface sediments (top 0-15 cm) of treated lakes, and whether As is being significantly remobilized. Eleven lakes were studied: five were known to have been treated with sodium arsenite; three were suspected of having been treated; and three untreated lakes were used for reference. Surface sediment grab samples were collected at multiple locations in each lake and analyzed for total As. In addition, water samples were collected along a vertical transect at the deepest point in each lake and analyzed for total As. In three of the five treated lakes and one of the lakes suspected of having been treated, sediment As concentrations were >100 mg/kg, or about four-fold higher than background. Analysis of the water samples showed that As was being remobilized from sediments of both the treated and untreated lakes where reducing conditions existed. The highest concentrations of dissolved As were measured in the bottom waters of treated lakes at levels >100 μg/L, which is about 50-fold higher than background. Elevated As levels in the sediments of treated lakes could have implications for lake management.
Long-term Increases in Oxygen Depletion in the Bottom Waters of Boulder Basin, Lake Mead, Nevada-Arizona, USAJames F. LaBounty; Noel M. BurnsLake and Reservoir Management1040-23810743-81412312007 69 - 82Long-term Increases in Oxygen Depletion in the Bottom Waters of Boulder Basin, Lake Mead, Nevada-Arizona, USA Long-term changes in the hypolimnetic volumetric oxygen demand (HVOD) of Boulder Basin, Lake Mead were determined from dissolved oxygen profiles collected from 1991 to 2007. HVOD is the rate at which oxygen in a deep layer in contact with the sediments is depleted during the period of thermal and/or chemical stratification. Generally, the rate at which oxygen is depleted is correlated to the amount of organic debris in the hypolimnion and sediments. The sediment oxygen demand reflects historical organic loading, while HVOD is a measure of productivity because of the organic particles settling from above. The lower hypolimnion in Boulder Basin remains relatively stable during the stratification period, enabling the calculation of HVOD in the near-bottom water layer. Small increases and/or decreases that occur in temperature and dissolved oxygen concentrations are detectable. Boulder Basin fully destratifies every other year on average, but mixes only partially in the spring (before May) of the remaining years. The HVOD rates after partial and complete destratification have been assessed separately for 1995-2005. The annual HVOD rate is generally lower the year after partial destratification than after complete destratification due to greater downward transport of oxygen into the hypolimnion. The HVOD of Boulder Basin is variable depending on loading of nutrients and water into the Basin. The rate dropped significantly following commencement of advanced wastewater treatment practices in 1994. The rates then increased 1996-2006 at a rate of approximately 0.75 mg DO/m3/day per year, or about 7% annually. During those years the inputs of nutrients steadily increased. Rates have been dropping from 2005 to present (2007) following further reduction of phosphorus input. A multiple regression analysis revealed that HVOD is significantly positive related to the total phosphorus concentration in Las Vegas Bay, but significantly negative to inflows of Colorado River water. That means HVOD was highest when reservoir water was nutrient-rich and flow rates were low. HVOD should be considered a major tool for monitoring trophic state changes in Boulder Basin.
Comparison of an Urban Lake Targeted for Rehabilitation and a Reference Lake Based on Robotic MonitoringJoseph S. Denkenberger; Charles T. Driscoll; Steven W. Effler; David M. O'Donnell; David A. MatthewsLake and Reservoir Management1040-23810743-81412312007 11 - 26Comparison of an Urban Lake Targeted for Rehabilitation and a Reference Lake Based on Robotic Monitoring A reference lake, Otisco Lake, NY, was selected to evaluate rehabilitation initiatives to mitigate severe cultural eutrophication of Onondaga Lake, NY. Onondaga Lake was mesotrophic before European development. The reference lake selection was based on an analysis of paired monitoring datasets for temperature, fluorometric chlorophyll (Chlf/a) and dissolved oxygen (DO), collected daily by robotic profiling platforms for the spring to fall interval of three years. The various metrics of trophic state documented here for Otisco Lake represent reasonable informal interim goals for the rehabilitation of the cultural eutrophication of Onondaga Lake. The use of Otisco Lake as a reference site is supported by its similar stratification/mixing regime and mesotrophic state, in addition to its proximity (~25 km) and similar morphometry with Onondaga Lake. Strong contrasts in water quality manifestations of trophic state are depicted in Onondaga Lake, including higher Chlf/a (3.5-fold), prevalence of blooms, greater deviations of DO from saturation conditions, much lower minimum DO values at fall turnover in the upper layers and a higher volumetric hypolimnetic oxygen deficit (VHOD; 1.55-fold). Advantages of the fine vertical and temporal scale capabilities of the monitoring platforms are demonstrated in characterizing these and other limnological features. Continued robotic monitoring at Otisco Lake as a reference site and Onondaga Lake through the rehabilitation program will support ongoing comparisons to assess progress and will help engage stakeholders in the process.
Inferred Phosphorus Cycling in Shallow and Deep Basins of Eutrophied Lake Hormajärvi, Southern FinlandSamu Valpola; Jutta Forsell; Veli-Pekka SalonenLake and Reservoir Management1040-23810743-81412312007 95 - 107Inferred Phosphorus Cycling in Shallow and Deep Basins of Eutrophied Lake Hormajrvi, Southern Finland Lake Hormajrvi is a typical small lake in southern Finland suffering from human-induced eutrophication. The lake has a complex basin morphology; the western basin is deeper and does not suffer the consequences of eutrophication of the shallower eastern basin, where poor water quality prevents swimming, fishing and other recreational use of the lake. Two short sediment cores from both basins were taken and studied to understand the eutrophication history of the lake, phosphorus (P) cycling within the respective basins and to evaluate needs for lake management and restoration. Sediments were analyzed for diatoms, P fractions, and physical properties. Spherical carbonaceous particles (SCP) were used for dating. Results indicate that diatom inferred autumnal lake surface water total P (DITP) does not follow the trend in accumulated P in the western basin, whereas there is a clear correlation in the eastern basin. The western basin acts as a permanent sink for P, but in the unstratified eastern basin, P released from sediment circulated throughout the water column. Results demonstrate that lake management or restoration decisions should not be made based on water quality and algal bloom observations alone. Detailed paleolimnological studies provide essential information to understand processes in complicated basins like Lake Hormajrvi.
Whole-lake Herbicide Treatments for Eurasian Watermilfoil in Four Wisconsin Lakes: Effects on Vegetation and Water ClarityKelly I. Wagner; J. Hauxwell; P. W. Rasmussen; F. Koshere; P. Toshner; K. Aron; D. R. Helsel; S. Toshner; S. Provost; M. Gansberg; J. Masterson; S. WarwickLake and Reservoir Management1040-23810743-81412312007 83 - 94Whole-lake Herbicide Treatments for Eurasian Watermilfoil in Four Wisconsin Lakes: Effects on Vegetation and Water Clarity Four pilot whole-lake herbicide treatments for extensive Eurasian watermilfoil (EWM) (Myriophyllum spicatum L.) infestations were conducted in Wisconsin between 1997 and 2001 using fluridone at a range of dosages (6-16 μg/L). Annual post-treatment data (4-7 years) were evaluated to assess (1) effects on exotic plants; (2) changes to native plant communities; and (3) effects on water clarity. Temporal shifts in treatment lakes were compared against natural fluctuations in untreated reference lakes. In conjunction with aggressive follow-up spot treatments with 2,4-D or manual removal, fluridone treatments provided between 1 and 4 years of substantial EWM relief, with the exotic ultimately re-establishing at pre-treatment levels or greater in 3 of the 4 lakes. Native plant communities shifted in all 4 lakes following fluridone treatment. The large decreases, outside the range seen in untreated lakes (first quartile of the reference lake distribution) for all treatment lakes containing EWM, Elodea canadensis, Ceratophyllum demersum, and Najas flexilis, strongly suggest a direct effect of the fluridone treatment. We observed large increases, outside the range seen in untreated lakes (fourth quartile of the reference distribution), for 1 of 2 treatment lakes with Potamogeton crispus, and 1 of 2 treatments with Chara spp. Secchi depth decreased significantly in 2 of the 3 lakes for which data were available. Future applications should consider, among other criteria, the dominant natives in the plant community, their sensitivity to fluridone, and potential impacts associated with decreased water clarity.
Potential Effects of Sediment Dredging on Internal Phosphorus Loading in a Shallow, Subtropical LakeK. R. Reddy; M. M. Fisher; Y. Wang; J. R. White; R. Thomas JamesLake and Reservoir Management1040-23810743-81412312007 27 - 38Potential Effects of Sediment Dredging on Internal Phosphorus Loading in a Shallow, Subtropical Lake Long-term phosphorus (P) loading to lakes has resulted in accumulation of P in sediments. Internal nutrient loading from sediments of shallow lakes such as Lake Okeechobee, Florida, has become a major concern in restoration programs. The objectives of this study were to determine (1) the potential impact of dredging on dissolved reactive P (DRP) flux out of sediments and (2) the equilibrium P concentration (EPCw) of post-dredge sediments. Intact sediment cores from one location representing P-laden mud sediments of the lake were obtained. Four simulated dredging treatments were implemented: control (no dredging-current conditions); top 30 cm; 45 cm; and 55 cm sediment removal. Phosphorus release/retention characteristics of sediments were determined at water-column DRP concentrations of 0, 0.016, 0.032, 0.064, and 0.128 mg/L. The water column in each core was replaced at approximately 60-day intervals, for a period of 1.2 years, with fresh lake water spiked with respective P concentrations. Significant decreases in water column DRP were observed only in sediment cores with 0-30 cm dredging. At ambient water column DRP levels, the P fluxes during the first 32 days were 0.4, 0.1, 0.4 and 0.2 mg P/m2/day for the 0, 30, 45, and 55 cm dredging treatments, respectively, and accounted for 11-38% of total P released during the 431 day study. At the end of the 1.2-year study, estimated EPCw were on the order of 0.033, 0.008, 0.022, and 0.037 mg P/L for 0, 30, 45 and 55 cm dredging treatments, respectively. Dredging the top 55 cm sediments would result in the removal of approximately 123 g P/m2, as compared to 80 and 108 g P/m2 for 30 and 45 cm dredging, respectively. Laboratory experiments suggest that dredging can reduce internal P loading. However, further evaluation is needed to determine the extent to which the controlled laboratory experiments can be used to predict fluxes in the lake under natural conditions, and the long-term sustainability of improving water quality by dredging.
Differential Prey Selectivity of Largemouth Bass Functional Feeding Groups in Twin Lakes, WashingtonDavid R. Christensen; Barry C. MooreLake and Reservoir Management1040-23810743-81412312007 39 - 48Differential Prey Selectivity of Largemouth Bass Functional Feeding Groups in Twin Lakes, Washington Largemouth bass (Micropterus salmoides) can be top-down regulators in a fish community. It is important for fisheries biologists who manage predator-prey populations to understand when bass become piscivorous. We examined the stomach contents of 622 largemouth bass in watershield (Brasenia schreberi) beds in North and South Twin Lakes, Washington. Bass displayed temporal and ontogenetic diet variation within and between lakes. Bass <100 mm fed principally on zooplankton and scuds in June and September and on benthic invertebrates, especially midge and damselfly larvae, during July and August. Damselflies, midges and scuds were major diet constituents for bass 100-199 mm. Bass 200-299 mm consumed large numbers of macroinvertebrates but also fed on crawfish and golden shiner (Notemigonus crysoleucus). Overall, the importance of large prey items like golden shiners and crawfish increased while macroinvertebrate importance to bass diets decreased as the fish grew larger. Bass piscivory was focused on golden shiners and was only observed in larger fish >300 mm. Golden shiner consumption was the lowest during June and September when cannibalism, crawfish and trout consumption increased. Temporal and ontogenetic variability in bass diets is most likely due to habitat variability, fish size, and prey availability and size. Manipulation of bass piscivory through slot-length-limits and/or macrophyte removal could be examined as a potential method for controlling nuisance forage fish such as golden shiners.
Posteruption Response of Phytoplankton and Zooplankton Communities in Spirit Lake, Mount St. Helens, WashingtonDouglas W. Larson; Jim Sweet; Richard R. Petersen; Charles M. CrisafulliLake and Reservoir Management1040-23810743-81412242006273 - 292Posteruption Response of Phytoplankton and Zooplankton Communities in Spirit Lake, Mount St. Helens, Washington Spirit Lake, Washington was radically altered limnologically by the May 1980 eruption of Mount St. Helens. The eruption provided a rare opportunity to study lake response and recovery in the wake of volcanic disturbance. During the eruption, and for several months thereafter, phytoplankton and zooplankton populations were subjected to extremely deleterious conditions. Consequently, these populations were virtually eliminated except for remnant organisms that somehow survived. During the next two years, the phytoplankton community and presumably the zooplankton community were comprised of only a few opportunistic species whose combined abundance was low. By 1983, however, phytoplankton abundance and species diversity had greatly increased due to increased lake-water transparency and increased availability of inorganic nitrogen. The reestablishment of the zooplankton community was also well underway by 1983, as indicated by the abundance of some species and the presence of most taxa that existed prior to the May 1980 eruption. By 1986, the phytoplankton and zooplankton communities were beginning to resemble those found in subalpine, oligotrophic/mesotrophic lakes in the Washington-Oregon Cascades. The rapid recovery of Spirit Lake demonstrated the vigor and resiliency of lake ecosystems and particularly plankton communities.
Limnological Characterization and Flow Patterns of a Three-coupled Reservoir System and Their Influence on Dreissena polymorpha Populations and Settlement During the Stratification PeriodEnrique Navarro; Montse Bacardit; Luciano Caputo; Toni Palau; Joan ArmengolLake and Reservoir Management1040-23810743-81412242006293 - 302Limnological Characterization and Flow Patterns of a Three-coupled Reservoir System and Their Influence on Dreissena polymorpha Populations and Settlement During the Stratification Period During summer 2001, zebra mussels (Dreissena polymorpha Pallas) were found (500 adults m-2) in the coupled reservoir system composed by Mequinenza, Riba-Roja and Flix (Ebro River, Northeast Spain). Two years later, mussels achieved densities of 4000 adults m-2, representing the first record of successful colonization by zebra mussels in the Iberian Peninsula. An August 2003 study investigated the environmental conditions that support the successful settlement of the zebra mussel populations during the stratification period. Flow patterns in the whole system and mussel populations near the dam were characterized. Chemical characteristics of water inputs, not the usual thermal stratification, determine the deep circulation of the Ebro River along the Riba-Roja reservoir, whereas water input from one tributary into Riba-Roja flows along the top of the water. Physico-chemical stratification of the water column seems to control the observed vertical distribution of zebra mussel biomass. Larger biomass and mean body size were found in the epilimnion, while meta- and hypolimnetic individuals were smaller in size and composed a lower biomass. Moreover, to know the influence of the water drawn off for electricity production in the settlement of mussel larvae, an artificial substratum (a rope) was placed in the influence area of the dam. Results indicate that flow conditions prevailing in the drawn-water layer may increase the attachment success of mussel larvae. Results show that during the stratification period the epilimnion of Riba-Roja was functioning as a 'biological reactor' where Dreissena populations thrived.
Watershed Development and Sediment Accumulation in a Small Urban LakeDavid J. Newman Jr.; David R. Perault; Thomas D. ShahadyLake and Reservoir Management1040-23810743-81412242006303 - 307Watershed Development and Sediment Accumulation in a Small Urban Lake The ever-increasing development of watersheds has raised the importance of assessing and mitigating the environmental impacts on water bodies located within disturbed areas. The removal of natural landcover can increase soil erosion and runoff along creeks and rivers, leading to heavier sediment build-up in ponds and lakes and to reductions in water quality and impoundment capabilities. For this paper, we described the possible impact from urbanization on sedimentation within a small lake. Landcover maps from two different time periods were compared against lake depths to assess relationships between development and sediment buildup. By understanding the mechanisms potentially leading to the ultimate loss of this lake, it is hoped that remediation strategies to reduce future degradation may be developed.
Effects of Small Ponds on Stream Water ChemistryG. Winfield Fairchild; David J. VelinskyLake and Reservoir Management1040-23810743-81412242006321 - 330Effects of Small Ponds on Stream Water Chemistry In many regions, small constructed ponds greatly exceed natural lakes in number and aggregate area. Many of these ponds are impoundments of small streams. Their effect in modifying stream water chemistry, however, remains poorly understood. Here we compare 19 physicochemical variables upstream vs. downstream of 11 ponds, sampled in March, May and July. The ponds greatly reduced inflow concentrations of SiO2 (by 71%), NO3- (by 82%) and PO43- (by 46%), while exporting water of higher pH, alkalinity and dissolved oxygen content, and much higher quantities of particulate and dissolved organic C, N and P than were present upstream. Higher % removals of NO3- and SiO2 were observed in ponds with longer hydraulic residence times. Based on ambient N:P ratios, algal periphyton below the ponds were likely P limited, but differential transformations of the components of total N vs. total P within the ponds greatly reduced N:P ratios downstream.
Application and Tests of the Canadian Water Quality Index for Assessing Changes in Water Quality in Lakes and Rivers of Central North AmericaJohn-Mark DaviesLake and Reservoir Management1040-23810743-81412242006308 - 320Application and Tests of the Canadian Water Quality Index for Assessing Changes in Water Quality in Lakes and Rivers of Central North America The Canadian Water Quality Index (CWQI) is a tool for communicating information to the general public and governments about water quality and assessing changes in water quality over time. It has been adopted for national and provincial reporting on water quality within Canada. It is used in this study to describe changes in water quality along a prairie river system and to assess changes in river water quality prior to and after the installation of tertiary clarifiers for the removal of phosphorus from wastewater effluent. CWQI values reflected the composite assessment of changes in individual parameter concentrations along the river. There was a slight increase in the CWQI after the installation of tertiary clarifiers, which reflected the improvement of only a few components of the wastewater. Several weaknesses of the CWQI were explored, including susceptibility to sample number per index period. A sound sampling design should form the basis of any monitoring program and, to a large extent, CWQI values are a reflection of the sampling program.
Book ReviewKenneth J. WagnerLake and Reservoir Management1040-23810743-81412242006342 - 343Book Review
Detection of Spatial and Temporal Trends in Wisconsin Lake Water Clarity Using Landsat-derived Estimates of Secchi DepthScott D. Peckham; Thomas M. LillesandLake and Reservoir Management1040-23810743-81412242006331 - 341Detection of Spatial and Temporal Trends in Wisconsin Lake Water Clarity Using Landsat-derived Estimates of Secchi Depth The existence of large-scale spatial and temporal trends in Wisconsin's lake water clarity is a topic that has not been thoroughly investigated. This study is an effort to reliably detect these trends by utilizing three inventories of satellite-derived lake water clarity predictions for over 2,000 lakes statewide. The data were analyzed statistically on a statewide, regional, lake type, and lake area basis. Statistically significant trends in clarity were found for the state overall, as well as for particular U.S. Environmental Protection Agency Ecoregions, Wisconsin Department of Natural Resources hydrologic lake types, and lake area categories. Results will aid in the establishment of a statewide lake water clarity database and demonstrate the effectiveness of satellite-based assessments in detecting trends in water transparency over the past three decades and into the future. Documenting such trends is essential to targeting and evaluating lake management practices as well as raising public awareness of lake clarity conditions throughout the state.
Temporal Variation and Assessment of Trophic State Indicators in Missouri Reservoirs: Implication for Lake Monitoring and ManagementMatthew F. Knowlton; John R. JonesLake and Reservoir Management1040-23810743-81412232006261 - 271Temporal Variation and Assessment of Trophic State Indicators in Missouri Reservoirs: Implication for Lake Monitoring and Management The magnitude and management implications of temporal variability in trophic state metrics was simulated by measuring mean values of total phosphorus (TP), total nitrogen (TN), chlorophyll (Chl) and Secchi depth (SD) in summer (May-August) and detecting trends in these variables in a virtual lake undergoing gradual (doubling over 20 years) and abrupt (doubling over two years) change. Numbers of samples required (samples per summer over number of summers) to adequately detect these rates of change were used to show the size and management implications of temporal variability. Long-term data from 116 Missouri reservoirs, including eight summer data sets based on daily sampling, provided estimates of autocorrelation and variation within and among summers (seasonal and year-to-year variance) used in Monte Carlo simulations to evaluate sampling requirements. In simulations based on median variance, obtaining long-term means with 95% confidence intervals spanning less than a factor of two took from three years (TN) to eight years (Chl) with monthly samples (n=3 per summer). For a lake with mean values doubling every 20 years, linear regression had >75% chance of detecting the trend after 13 years of monthly samples for TN, but Chl required >20 years. For a lake with Chl doubling over two years, at least six years of pre-change data and 11 years of post-change data were required before monthly sampling gave >75% probability of detecting the trend. Increasing sampling to weekly frequency (n=16 per summer) in most scenarios reduced required duration of sampling by <2 years. Variability data from lakes in other regions fall in the range exhibited by Missouri reservoirs. Results emphasize the need for long-term data to fulfill lake management needs and suggest that ordinary lake monitoring typically will not detect trends in individual lakes.
Influence of Chlorophyll and Colored Dissolved Organic Matter (CDOM) on Lake Reflectance Spectra: Implications for Measuring Lake Properties by Remote SensingKevin D. Menken; Patrick L. Brezonik; Marvin E. BauerLake and Reservoir Management1040-23810743-81412232006179 - 190Influence of Chlorophyll and Colored Dissolved Organic Matter (CDOM) on Lake Reflectance Spectra: Implications for Measuring Lake Properties by Remote Sensing Light reflected from lake surfaces can convey much information about water quality, especially algal abundance, humic content, turbidity and suspended solids. Light reflectance from lakes is complicated, and detailed spectra are needed for analysis of controlling factors. We obtained detailed reflectance spectra from the water surfaces of 15 lakes in east-central Minnesota and found patterns related to chlorophyll a (chl a), turbidity and humic matter (colored dissolved organic matter, CDOM). Increasing chl a and turbidity generally resulted in higher reflectance across the visible and near-infrared spectrum. Increasing CDOM led to low reflectance, especially below ~500 nm. Spectra of lakes with high chl a were distinguishable from those of lakes low in chl a, and lakes with low or high CDOM had readily distinguishable spectra. Several optical characteristics of lake water can be estimated from reflectance intensities measured over narrow wavelength bands. The ratio of reflectance at 700 nm to that at 670 nm was the best predictor of chl a over a wide range of conditions, including high turbidity and CDOM. Several relationships involving reflectance at 412, 443, 488, and 551 nm, the wavelengths used to calculate oceanic chl a from MODIS satellite data, also yielded a high R2. The ratio of reflectance at 670 nm to 571 nm provided the best estimates of humic color despite the low absorbance of CDOM at these wavelengths. Relationships involving reflectance for all 15 lakes in the range 400-500 nm, where CDOM absorbs light, had low r2 values; none was high enough for reliable estimates of lake color. For 10 lakes with low to medium chl a levels (≤10 mg m-3), regressions involving 412 and 443 nm yielded moderately good relationships. Airborne and satellite remote sensing thus might be used to identify lakes high in CDOM, and may provide reasonable estimates of humic color in lakes with low chl a levels.
Preliminary Results of Light Transmission under Residential Piers in Lake Washington, King County, Washington: A Comparison between Prisms and GratingPerry F. Gayaldo; Kitty NelsonLake and Reservoir Management1040-23810743-81412232006245 - 249Preliminary Results of Light Transmission under Residential Piers in Lake Washington, King County, Washington: A Comparison between Prisms and Grating During the summers of 2003 and 2004, 11 piers (two public and nine private) were evaluated for their ability to transmit light through the decking to the water surface below. Solid decking produces distinct shading that migrating juvenile Chinook salmon appear to avoid by swimming into deeper water where more potential predators live. Two new types of surface treatments (acrylic prisms and grating) were evaluated and compared to traditionally spaced decking as well as solid decking. Grating (with 37-58% open space) was found to transmit significantly more light to the water surface below (mean = 7.5% of full sunlight) than 23 5 cm acrylic prisms (mean = 0.7% of full sunlight). In other words, compared to full sunlight, grating transmits 10 times more light under the pier than acrylic prisms. In addition, light that passes through open grating penetrates the water evenly under the pier. Light transmitted through prisms concentrates beams of light that do not always reach the water surface.
Estimation of Sediment Volume in Karaj Dam Reservoir (Iran) by Hydrometry Method and a Comparison with Hydrography MethodMohammad Heidarnejad; Said Hassan Golmaee; Abolfazl Mosaedi; Mirkhalegh Z. AhmadiLake and Reservoir Management1040-23810743-81412232006233 - 239Estimation of Sediment Volume in Karaj Dam Reservoir (Iran) by Hydrometry Method and a Comparison with Hydrography Method Estimation of sediment volume in the reservoirs is an important management criterion in water use. Many methods are used for this purpose, including hydrography, remote sensing, hydrometry and mathematical and computer models. The high cost of field methods such as hydrography required other methods to be investigated more seriously. In the present research, the hydrometry method was used to estimate the sediment volume in Karaj Dam Reservoir, located on the southern slope of Mount Alborz of Iran. The estimation is based on evaluation of both suspended and bed-load sediments. Although the sediment rating curve method is not common in general, using corrected models based on effective factors of sediment transfer, such as time of measurement, have increased the model efficiency. For this purpose, the daily and annual suspended loads were estimated in two hydrometric stations of Seera and Beylaghan (inlet and outlet hydrometric stations of Karaj Dam) using daily water flow rates and monthly sediment rating equations. Because the empirical methods of bed load sediment did not give acceptable results, the Karaushev curve (which has suitable compatibility with Iranian rivers) was used and the ratio of bed load to suspended load was obtained based on the river slope at hydrometric stations. By using total sediment load and average sediment density, the volumes of sediment were calculated for dam inlet and outlet hydrometric stations. Subtraction of the two volumes gave the stored annual sediment in reservoir of about 406,000 m3. The sediment volume resulting from the hydrography method (from dam primary and secondary area-volume curves) was 416,000 m3, which gave 97% collation, and the trapping efficiency of the Karaj Dam was calculated to be 80%.
Development and Application of Rapid Antibiotic Resistance Analysis for Microbial Source Tracking in the Black River Watershed, MichiganLisa VanOmmeren; Elizabeth W. AlmLake and Reservoir Management1040-23810743-81412232006240 - 244Development and Application of Rapid Antibiotic Resistance Analysis for Microbial Source Tracking in the Black River Watershed, Michigan Microbial source tracking (MST) is often a desirable component of water quality monitoring. To enable local health departments to utilize MST regularly, rapid methods need to be developed that can be performed without costly equipment, increased laboratory space, or advanced technical requirements. This paper describes the development, validation, and application of a rapid, small-scale MST method based on antibiotic resistance analysis. An automated plate reader allows for earlier and repeated measurements and can distinguish treatment effects after only six hours of incubation, compared with the overnight incubation for the conventional assay. Using this rapid MST assay, a known-source Escherichia coli (E. coli) antibiotic resistance pattern database was constructed for the Black River watershed in southeastern Michigan. The average rate of correct classification for the known-source database was 70.4% when comparing each of seven specific animal sources, 72.5% when comparing three generic animal groups (human, waterfowl, and livestock), and 88.9% when comparing human to non-human animal sources. The rapid assay and database were then used to identify the sources of E. coli at a public recreational beach as human (34%), goose (34%), and cattle (20%).
Use of Robotic Monitoring to Assess Turbidity Patterns in Onondaga Lake, NYSteven W. Effler; David M. O'Donnell; Feng Peng; Anthony R. Prestigiacomo; MaryGail Perkins; Charles T. DriscollLake and Reservoir Management1040-23810743-81412232006199 - 212Use of Robotic Monitoring to Assess Turbidity Patterns in Onondaga Lake, NY Selected temporal and vertical patterns of turbidity (Tn) are documented for an eutrophic urban lake, Onondaga Lake, NY, and their diagnostic value in identifying hydrodynamic and metabolic processes and in estimating clarity is established. The analysis is supported by five years (spring to fall) of daily robotic profiling of Tn, temperature (T), and dissolved oxygen, and an array of more temporally limited measurements that included Tn and T levels in the major tributary input of terrigenous solids; lake particle characterizations with a profiling particle counter and a scanning electron microscope coupled with automated image analysis and X-ray microanalysis; and Secchi disc transparency (SD). Major runoff events are demonstrated to cause conspicuous short-term increases in Tn that are manifested as metalimnetic peaks in summer and early fall, associated with the entry of the negatively buoyant primary tributary source as an interflow. The annual occurrence of Tn maxima within the oxycline of the metalimnion in October is documented. Evidence supports the position that this layer is a bacterial plate of oxidizing bacteria that develops seasonally in response to increasing vertical transport of reduced species from the hypolimnion with the approach to fall turnover. A strong relationship between SD and Tn in the upper waters is reported, that is demonstrated to have utility in resolving the dynamics of substantial changes in SD that occur in the lake during clear water phases.
Application of a 2-Dimensional Water Quality Model (CE-QUAL-W2) to the Turbidity Interflow in a Deep Reservoir (Lake Soyang, Korea)Yoonhee Kim; Bomchul KimLake and Reservoir Management1040-23810743-81412232006213 - 222Application of a 2-Dimensional Water Quality Model (CE-QUAL-W2) to the Turbidity Interflow in a Deep Reservoir (Lake Soyang, Korea) The temporal and spatial distribution of water temperature was surveyed and simulated in a deep warm monomictic reservoir (Lake Soyang, Korea). The great depth (maximum depth 118 m) and wind-sheltered dendritic shape caused stable thermal stratification in summer. Turbid storm runoff during the summer monsoon formed a 20-40 m intermediate layer distinct from the clearer epilimnion and hypolimnion. The temperature distribution and movements of the density current were simulated by using the 2-dimensional hydrologic model, CE-QUAL-W2. The model was calibrated with data from 1996 and verified with data from 1995-2002 by applying the same set of parameters and constants as used in calibration. The model could simulate temperature profiles with excellent agreement. Movement of the intermediate density current also was well simulated. The CE-QUAL-W2 model was useful in the prediction of temperature distribution and movement of density current in reservoirs, which implies merit for further employment of this model in water quality simulations.
Effects of Hypolimnetic Releases on Two Impoundments and Their Receiving Streams in Southwest WisconsinDavid W. Marshall; Matt Otto; John C. Panuska; Steven R. Jaeger; Donna Sefton; Thomas R. BaumbergerLake and Reservoir Management1040-23810743-81412232006223 - 232Effects of Hypolimnetic Releases on Two Impoundments and Their Receiving Streams in Southwest Wisconsin The effects of bottom water withdrawals were evaluated within and below two southwestern Wisconsin impoundments. Like many man-made lakes in the unglaciated area of Wisconsin, Twin Valley Lake and White Mound Lake were constructed during the late 1960s for flood control and recreation. Both impoundments, which are located in large agricultural watersheds, were originally designed to release cold bottom water with the intended goal of managing trout below the dams. However, recent water quality monitoring results revealed that the streams became degraded due to frequent dissolved oxygen criterion violations and excessive filamentous bacteria growths. Organic loading from the bottom discharges is the likely reason that trout stream habitat was not successfully created below the dams as originally intended. Despite the accelerated phosphorus removal from the long-term withdrawals, blue-green algal blooms continued to be a problem in both impoundments. While maximizing total phosphorus export can improve lake water quality conditions, discharge rates from these impoundments were found to be excessively high, resulting in disturbance of their thermo-structure and entrainment of nutrients into the surface waters. In 2005, we blocked the bottom gate at Twin Valley Lake and monitored water quality and thermal responses. As a result, lake and stream water quality improved significantly while the downstream fish community structure did not change. The impoundment thermo-structure was restored with well-defined hypolimnion and epilimnion. We conclude that managing impoundments is often a balancing act between seemingly disparate goals of achieving optimum conditions above or below a dam, with undesirable consequences often occurring if the focus is disproportionately on a single goal.
Water Quantity and Quality of Mansar Lake Located in the Himalayan Foothills, IndiaVijay Kumar; S. P. Rai; Omkar SinghLake and Reservoir Management1040-23810743-81412232006191 - 198Water Quantity and Quality of Mansar Lake Located in the Himalayan Foothills, India Bathymetric survey and physico-chemical analysis of Mansar Lake, located in the Himalayan foothills in the state of Jammu and Kashmir, India, were carried out to assess water quantity and quality. The bathymetric survey indicated that Mansar Lake, with a surface area of 0.59 106 m2 at present outflow level, has a maximum depth, length and width of 38.25 m, 1204 m and 645 m, respectively. The lake mean width is 490 m, mean depth is 21 m, and mean slope of the lake floor is 0.14 m·m-1. The storage capacity of the lake up to present outflow level is 11.57 106 m3. Vertical variation of temperature, pH, electrical conductivity, dissolved oxygen, hardness and alkalinity suggest that Mansar Lake undergoes complete mixing during January and February and is stratified in other months. Calcium, magnesium and sodium are the dominant cations, and bicarbonate the dominant anion. Analysis of chemical parameters shows that the lake water is of Ca-Mg-HCO3-CO3 type. Phosphate concentration >0.03 mg·L-1 in the Mansar Lake water indicated that the lake is eutrophic. Suitable measures have been suggested for sustainable management of Mansar Lake.
Seasonal Dynamics of Phytoplankton Assemblages across Nutrient Gradients in Shallow Hypertrophic Lake Manyas, TurkeyKemal Çelik; Tuğba OngunLake and Reservoir Management1040-23810743-81412232006250 - 260Seasonal Dynamics of Phytoplankton Assemblages across Nutrient Gradients in Shallow Hypertrophic Lake Manyas, Turkey Species composition, abundance and size distribution (the average measure of the longest cell dimension and surface area to volume ratio) of phytoplankton in the shallow hypertrophic Lake Manyas, Turkey were studied between January 2003 and December 2004. A total of 165 species were recorded during the study. Diatoms and Cyanobacteria were the dominant taxa at most stations. Nitrate and phosphate values showed a decreasing gradient with the distance from Sigirci Inlet to Karadere Outlet. Bacillariophyta dominated the phytoplankton in spring, while Cyanobacteria prevailed in summer. Each summer, a peak of Euglenophyta was also observed at Sigirci Inlet. Nutrient gradients seemed to have a greater control over overall density than of species composition. The size distribution of the Cyanobacteria showed positive correlations with nutrient levels, while green algae and diatoms did not. There was a negative correlation between the average cell dimension of the phytoplankton cells and the surface area to volume ratio in general. The objective of this study was to determine the seasonal dynamics of species composition, abundance and size distribution of phytoplankton assemblages across nutrient gradients along a distance in the shallow hypertrophic Lake Manyas, Turkey.
Three-dimensional Management Model for Lake Washington, Part I: Introduction and Hydrodynamic ModelingSung-Chan Kim; Carl F. Cerco; Billy H. JohnsonLake and Reservoir Management1040-23810743-81412222006103 - 114Three-dimensional Management Model for Lake Washington, Part I: Introduction and Hydrodynamic Modeling A three-dimensional hydrodynamic model, CH3D-Z (curvilinear hydrodynamics in three dimension, Z-grid version), was implemented in Lake Washington as a part of a management model. The model was calibrated for hydrothermal distribution over a one-year time period for 1995 and verified for a two-year time period between 1996 and 1997. Simulation reproduced intra-annual variation of mixing represented by fall/winter mixing and spring/summer stratification. The simulated variation of vertical thermal structures also matched observation. Vertical flux was investigated in terms of stratification through turbulent mixing and internal waves. Basin scale internal waves showed a characteristic diurnal variation and modulation by surface wind. The model resolved the seasonal variation of thermal structures, assuring a good linkage to a nutrient-eutrophication model.
Comparison of Multiple Point and Composite Sampling for Monitoring Bathing Water QualityJulie L. Kinzelman; Alfred P. Dufour; Larry J. Wymer; Gareth Rees; Kathy R. Pond; Robert C. BagleyLake and Reservoir Management1040-23810743-8141222200695 - 102Comparison of Multiple Point and Composite Sampling for Monitoring Bathing Water Quality The United States Environmental Protection Agency's Beaches Environmental Assessment and Coastal Health Act (BEACH Act) requires states to develop monitoring and notification programs for recreational waters using approved bacterial indicators. Implementation of an appropriate monitoring program can, under some circumstances, be expensive. This study explored the use of composite sampling at two Racine, Wisconsin beaches over a four month period (n = 68 days) to determine whether compositing can provide a valid, unbiased, and cost-effective measure of water quality. Multiple point sampling occurred throughout the bathing season, with water samples collected daily from three or four fixed locations along each beach. From each individual sample, well-mixed aliquots were combined to form a composite sample. Individual and composite samples were assayed identically for Escherichia coli using Colilert-18 and Quanti-Tray 2000 (IDEXX Laboratories, Inc., Westbrook, ME). Results from this study indicate a reasonable expectation of a simple 1:1 ratio between the composite samples and the arithmetic mean of the individual samples. Additionally, log variance of the composite sample results did not differ significantly from that of the single sample averages (p > 0.2). Empirical values for log standard deviations varied by no more than 7% between the composite sample and individually assayed samples. Thus compositing, as performed in this study, appears to introduce neither significant bias nor additional variability into the monitoring results and stands as a reasonable alternative to data sets derived from single-sample methods. Regulatory programs adopting this approach could maintain sample integrity while reducing costs associated with recreational water quality assessment.
Natural Variability in Lakes and Reservoirs Should be Recognized in Setting Nutrient CriteriaMatthew F. Knowlton; John R. JonesLake and Reservoir Management1040-23810743-81412222006161 - 166Natural Variability in Lakes and Reservoirs Should be Recognized in Setting Nutrient Criteria Long-term data on total phosphorus (TP) and chlorophyll (Ch1) from statewide summer monitoring of Missouri reservoirs (n=p141) and daily collections from 6 summer seasons from Lake Woodrail (n=705) illustrate the magnitude of temporal variability in regional impoundments and the problem of assessing compliance with numeric nutrient criteria. Among individual observations, >24% of Chl values and >14% of TP values were >150% of long-term means in both data sets. Seasonal means varied by ~2-fold among years in Woodrail and by >3-fold in many reservoirs statewide. Simulated numeric criteria of 27 μg/L TP and 10 μg/L Chl were exceeded by 18-24% of individual measurements and 16-24% of seasonal means from reference reservoirs whose long-term means met these criteria. Seasonal mean values based on a single summer misclassified 15-17% of Missouri reservoirs with respect to the status of their long-term averages (8 or more seasons). Given this level of temporal variation, numeric criteria determined from average conditions in reference lakes should be applied only to long-term averages in target lakes. Rules for assessing compliance with nutrient standards should be framed with anticipation of the widely varying conditions in individual lakes.
Determining Ecoregional Reference Conditions for Nutrients, Secchi Depth and Chlorophyll a in Kansas Lakes and ReservoirsWalter K. Dodds; Edward Carney; Robert T. AngeloLake and Reservoir Management1040-23810743-81412222006151 - 159Determining Ecoregional Reference Conditions for Nutrients, Secchi Depth and Chlorophyll a in Kansas Lakes and Reservoirs Baseline environmental conditions are a critical consideration in the development of scientifically defensible aquatic nutrient criteria. We applied three methods to ecoregionally stratified data to determine reference conditions in Kansas lakes and reservoirs with respect to total phosphorus, total nitrogen, Secchi depth, and planktonic chlorophyll a (chl a). First, minimally developed lake/watershed units were identified based on existing geographical databases and visual basin surveys. Lakes and reservoirs in these watersheds were considered minimally-to-least impacted “reference” waters. Second, median nutrient, Secchi depth, and chl a values were determined for the best one-third of lakes and reservoirs and applied as indicators of reference condition (trisection). Third, a regression-based extrapolation method was applied to estimate water quality conditions in the absence of anthropogenic influences. The first method suggested no ecoregional effect on the trophic status of minimally impacted reference water bodies, whereas the other two methods indicated some significant ecoregional differences. Lack of ecoregional effect in reference bodies could indicate that differences were driven by anthropogenic influences rather than natural regional characteristics. Reference conditions, as determined by these three methods, broadly agreed for all parameters and were generally at or less than literature values for the mesotrophic-eutrophic threshold for lakes and reservoirs worldwide. Reference values for total phosphorus were primarily less than levels commonly associated with cyanobacterial blooms. Overall, the data suggest that multiple methods can be used to determine reference condition, and that in Kansas lakes and reservoirs reference condition corresponds to mesotrophic state.
Total Coliform and Escherichia Coli Counts in 99 Florida Lakes with Relations to Some Common Limnological FactorsMark V. Hoyer; Jennifer L. Donze; Eric J. Schulz; Daniel J. Willis; Daniel E. Canfield Jr.Lake and Reservoir Management1040-23810743-81412222006141 - 150Total Coliform and Escherichia Coli Counts in 99 Florida Lakes with Relations to Some Common Limnological Factors The degree of bacterial contamination of 99 Florida lakes was studied using total coliform and Escherichia coli (E. coli) counts as indicators. Over 75% of the 4055 samples analyzed for total colifoms and over 98% analyzed for E. coli were below Florida's state standards for total and fecal coliform bacteria, respectively. Thus, there is little evidence of widespread fecal contamination in the Florida lakes examined during this study. Future bacterial sampling in lake systems should consider the facts that open-water samples had significantly lower total coliform and E. coli counts than littoral samples, and that the variance in bacterial counts is greater among lakes over time than spatially within lakes. Additionally, lake trophic status and aquatic bird abundance were also positively related to both total coliform and E. coli counts, while lake surface area and percent area covered with aquatic macrophytes (PAC) showed no significant relations. The method of waste management around lakes is often a concern to many people citing septic tank systems for polluting aquatic systems. However, the data examined in this study showed no difference in bacterial counts between lakes managing waste with septic tanks and those with central waste water treatment systems. A routine, inexpensive bacterial monitoring program is recommended for lakes used for body-contact recreational activities to be safe and relieve concerns of the public about potential health problems.
Three-dimensional Management Model for Lake Washington, Part II: Eutrophication Modeling and Skill AssessmentCarl F. Cerco; Mark R. Noel; Sung-Chan KimLake and Reservoir Management1040-23810743-81412222006115 - 131Three-dimensional Management Model for Lake Washington, Part II: Eutrophication Modeling and Skill Assessment The CE-QUAL-ICM 3-dimensional eutrophication model was applied to Lake Washington for the period 1995-1997. Transport processes were obtained from the companion CH3D-WES hydrodynamic model. The model activated 18 state variables in the water column, including physical variables; phytoplankton; multiple forms of carbon, nitrogen, and phosphorus; dissolved oxygen; and fecal coliform. The water column was coupled to a sediment diagenesis model that computed sediment-water fluxes of dissolved oxygen, methane, ammonium, nitrate, and phosphate, based on computed inputs of particulate organic matter. The model successfully computed the annual cycles and spatial distributions of key water quality components. Nutrient loads were calculated and nutrient budgets were constructed as part of the model exercise. Load sources included river inflows, distributed loads, sewer overflows and atmospheric loading. The Sammamish River was identified as the largest source of nutrients to Lake Washington, followed by the Cedar River and other distributed sources. The majority of the nutrient load is deposited in the sediments. A lesser amount leaves via Lake Union. Our nutrient loads were 30% (nitrogen) to 60% (phosphorus) higher than the loads from the late 1970s.
A Review of Factors Affecting the Distribution and Abundance of Rainbow Trout (Oncorhynchus mykiss Walbaum) in Lake and Reservoir SystemsStephen SwalesLake and Reservoir Management1040-23810743-81412222006167 - 178A Review of Factors Affecting the Distribution and Abundance of Rainbow Trout (Oncorhynchus mykiss Walbaum) in Lake and Reservoir Systems Rainbow trout distribution and abundance in lakes and reservoirs has been correlated with a wide range of physical, chemical and biological factors. In North American lakes and reservoirs, distribution and abundance are affected by variables such as lake elevation, water chemistry, and lake morphology, as well as biological factors such as food availability and competition with other fish species. Chemical and physical features that serve as indices of biological productivity, including pH, alkalinity, total dissolved solids and morpho-edaphic index, have been related positively to trout abundance. Rainbow trout occurrence and distribution in lakes and reservoirs is determined mostly by a combination of factors, notably the concentration of dissolved oxygen, water temperature and food. The upper water temperature threshold for rainbow trout habitat in lakes is generally around 21°C, while a dissolved oxygen concentration of 2.5 mg L-1 is generally taken as the lower limit for distribution.
Analysis of Environmental Variation in a Great Plains Reservoir Using Principal Components Analysis and Geographic Information SystemsJames M. Long; William L. FisherLake and Reservoir Management1040-23810743-81412222006132 - 140Analysis of Environmental Variation in a Great Plains Reservoir Using Principal Components Analysis and Geographic Information Systems We present a method for spatial interpretation of environmental variation in a reservoir that integrates principal components analysis (PCA) of environmental data with geographic information systems (GIS). To illustrate our method, we used data from a Great Plains reservoir (Skiatook Lake, Oklahoma) with longitudinal variation in physicochemical conditions. We measured 18 physicochemical features, mapped them using GIS, and then calculated and interpreted four principal components. Principal component 1 (PC1) was readily interpreted as longitudinal variation in water chemistry, but the other principal components (PC2-4) were difficult to interpret. Site scores for PC1-4 were calculated in GIS by summing weighted overlays of the 18 measured environmental variables, with the factor loadings from the PCA as the weights. PC1-4 were then ordered into a landscape hierarchy, an emergent property of this technique, which enabled their interpretation. PC1 was interpreted as a reservoir scale change in water chemistry, PC2 was a microhabitat variable of rip-rap substrate, PC3 identified coves/embayments and PC4 consisted of shoreline microhabitats related to slope. The use of GIS improved our ability to interpret the more obscure principal components (PC2-4), which made the spatial variability of the reservoir environment more apparent. This method is applicable to a variety of aquatic systems, can be accomplished using commercially available software programs, and allows for improved interpretation of the geographic environmental variability of a system compared to using typical PCA plots.
Assessment of Long-term Trends in the Oxygen Resources of a Recovering Urban Lake, Onondaga Lake, New YorkDavid A. Matthews; Steven W. EfflerLake and Reservoir Management1040-23810743-8141221200619 - 32Assessment of Long-term Trends in the Oxygen Resources of a Recovering Urban Lake, Onondaga Lake, New York Long-term trends in dissolved oxygen (DO) resources are documented for ionically enriched, hypereutrophic Onondaga Lake, New York, for 1978-2002. Assessments of oxygen resources are based on DO profiles of 1 m resolution conducted hourly to weekly during April-October. Closure of an industry that operated on the lake's shore until 1986 resulted in an abrupt decrease in primary production and organic carbon deposition and marked changes in hypolimnetic and epilimnetic DO regimes. The hypolimnetic DO response was gradual, reflecting the influence of sediment feedback. The onset of complete hypolimnetic anoxia, which occurred by early June through the 1980s, took place approximately one month later over 1997-2002. The anoxic factor decreased significantly over the study interval, from 97±5 d to 67±2 d. Epilimnetic DO concentrations responded rapidly to the abrupt change in lake metabolism. Before closure of the industry, 41% of the April to mid-September DO observations deviated from saturation concentrations by >30%. In the years immediately following industry closure, this degree of disequilibrium occurred in 23% of DO observations. Percent saturation values during fall turnover increased gradually during the study, from 49±2 to 65±2. DO concentrations in the lake's upper waters have been subject to substantial diel fluctuations (>4 mg/L), with daily minima and maxima generally occurring at approximately 7:00 and 16:00, respectively. Measurements made at 11:00 and 22:00 were most likely to be representative of daily average conditions. Diel variations and sampling frequency were demonstrated to be important issues for the evaluation of status with respect to water quality standards for DO. Levels of DO in the lake's upper waters have been positively correlated with chlorophyll a concentrations (r = 0.52). Despite marked improvements in DO resources, the lake continues to lack cool, well-oxygenated waters during summer necessary to support coldwater fish species.
Resolution of Turbidity Patterns from Runoff Events in a Water Supply Reservoir, and the Advantages of In Situ Beam Attenuation MeasurementsSteven W. Effler; Anthony R. Prestigiacomo; Feng Peng; Katerina B. Bulygina; David G. SmithLake and Reservoir Management1040-23810743-8141221200679 - 93Resolution of Turbidity Patterns from Runoff Events in a Water Supply Reservoir, and the Advantages of In Situ Beam Attenuation Measurements The impact of runoff events on light scattering, or turbidity, levels in a water supply reservoir, and the comparative performance of three surrogate metrics of light scattering, are documented for the spring through fall interval of a high runoff year. The analysis is supported by: (1) frequent (42 d) field measurements of the beam attenuation coefficient at 660 nm (c660) and “optical” backscattering (OBS) collected with rapid profiling instrumentation at multiple sites; (2) laboratory measurements of c660 and turbidity (Tn); and (3) characterizations of inorganic particles with scanning electron microscopy interfaced with automated image and X-ray analyses. Conspicuous increases in light scattering levels are reported following runoff events, as reflected in increases in c660, OBS and Tn, associated with terrigenous inputs of clay minerals. The extent of this impact is demonstrated to be driven by the magnitude of the runoff event. Terrigenous inputs of turbidity are shown to enter as density currents, which travel the entire length of the reservoir for major runoff events, manifested as peak scattering levels in subsurface layers. Strong longitudinal and lateral differences are documented soon after runoff peaks. Scattering levels and spatial gradients are shown to diminish rapidly, with pre-event conditions approached within a week. Systematically lower c660 values are reported for laboratory measurements compared to in situ observations, particularly at high scattering levels, consistent with the operation of particle coagulation. In situ measurement of c660is identified as the preferred surrogate metric of light scattering.
A DNA Fingerprinting Approach for Distinguishing Native and Non-native MilfoilsRyan A. Thum; Jay T. Lennon; Jody Connor; Amy P. SmagulaLake and Reservoir Management1040-23810743-814122120061-6A DNA Fingerprinting Approach for Distinguishing Native and Non-native Milfoils Variable-leaf water milfoil, Myriophyllum heterophyllum, is a non-native aquatic plant that has become a major management concern in New England. One key obstacle for effective management is accurate identification of native and non-native milfoil species. We used DNA sequences from the nuclear ribosomal DNA internal transcribed spacers (ITS) to identify non-native populations of M. heterophyllum. We found a number of discrepancies among morphological and genetic identifications, including individuals that were morphologically identified as natives but genetically identified as non-natives, and vice versa. We attribute these discrepancies to inaccurate identifications arising from morphological similarities among milfoil species. To help remedy this problem, we developed a restriction enzyme assay that distinguishes non-native M. heterophyllum from native milfoils. The assay provides a reliable method for identifying M. heterophyllum and therefore should facilitate lake management decisions concerning native and non-native milfoil populations.
A Review of the Components, Coefficients and Technical Assumptions of Ontario's Lakeshore Capacity ModelA. M. Paterson; P. J. Dillon; N. J. Hutchinson; M. N. Futter; B. J. Clark; R. B. Mills; R. A. Reid; W. A. ScheiderLake and Reservoir Management1040-23810743-814122120067-18A Review of the Components, Coefficients and Technical Assumptions of Ontario's Lakeshore Capacity Model Phosphorus is the nutrient that most often limits the primary productivity of inland lakes on the Precambrian Shield. Recognizing the need to develop quantitative relationships to assess the impact of shoreline development on phosphorus concentrations in lakes, the Lakeshore Capacity Model (LCM) was developed by the Ontario Ministry of the Environment, Canada. The LCM is a steady-state mass-balance model that uses empirical relationships to predict the ice-free total phosphorus concentration of a lake. The model, calibrated and tested on lakes on the Precambrian Shield, has subsequently formed the basis for management decisions in the public and private sectors. Over the past two decades the coefficients, input parameters and assumptions of the LCM have been modified and updated to reflect an improved scientific understanding of the relative importance of sources and losses of phosphorus in lakes and watersheds. Here we present a comprehensive review of the components, coefficients and assumptions of the most recent version of the LCM (v. 3.0), providing a standard reference for all users of the model.
Predicting Sediment Physical Properties within a Montane Lake Basin, Southern Coast Mountains, British Columbia, CanadaErik SchieferLake and Reservoir Management1040-23810743-8141221200669 - 78Predicting Sediment Physical Properties within a Montane Lake Basin, Southern Coast Mountains, British Columbia, Canada The variability of lacustrine sediment physical properties was examined for a small montane lake in the southern Coast Mountains of British Columbia. A high-density sampling scheme (1 core per 0.01 km2) was utilized for sediment sampling within the 2 km2 lake basin. Vertical patterns in the upper sediment record were controlled by compaction effects with interruptions by major sediment delivery event beds and organic debris deposits. Primary patterns of lateral variability were associated with proximity to the principal lake inflow. A simple sedimentation model based on Stokes Law was shown to reasonably predict down-lake variations of sediment texture. A significant influence of water depth was observed in shallow water settings where highly variable sediment characteristics were observed. Secondary spatial patterns were related to localized rapid deposition effects and past land-use activities. Sedimentary parameters of water content, bulk density, organic content, and particle size were shown to be interrelated to varying degrees. Water content may be used as a key parameter for predicting other physical properties because of its strong negative relation with sediment density, moderate positive relation with organic content, and non-linear association with mean particle size.
Spatial and Temporal Dynamics of Microcystin in a Missouri ReservoirJennifer L. Graham; John R. Jones; Susan B. Jones; Thomas E. ClevengerLake and Reservoir Management1040-23810743-8141221200659 - 68Spatial and Temporal Dynamics of Microcystin in a Missouri Reservoir Environmental factors associated with spatiotemporal variation of microcystin (MC) in Mozingo Lake, a Missouri reservoir, were studied during summer 2001, and annual MC trends were characterized from May 2001-May 2002. MC increased during summer, ranging from 20 to1220 ng/L. Seasonal patterns in MC corresponded with chlorophyll >35 μm (Net Chl) and cyanobacterial biovolume associated with increased dominance by Microcystis and Anabaena. MC showed strong negative correlations with dissolved nitrogen (r=-0.95) and cations (r=-0.98), and strong positive correlations with Net Chl (r=0.91). Once the lake stratified, MC and Net Chl remained uniform throughout the photic zone and decreased significantly (p<0.05) in the aphotic zone. Field experiments indicated MC did not change independently of Net Chl in response to decreased light or increased nutrients; however, enclosure effects may have substantially influenced experimental results. Mozingo Lake MC was tightly coupled with seasonal lake processes, including stratification and nutrient loss from the epilimnion, and cyanobacterial community composition, abundance and distribution in the water column. MC was detected in all monthly samples suggesting the potential for problems associated with MC exists year round, but peaks in early fall presented the greatest concern in Mozingo Lake.
Variation in Water Quality and Phytoplankton Nutritional Status in an Urbanized Lake System (Lake Merced, California, USA)Albert M. Marchi; Hunter J. CarrickLake and Reservoir Management1040-23810743-8141221200633 - 43Variation in Water Quality and Phytoplankton Nutritional Status in an Urbanized Lake System (Lake Merced, California, USA) Lake chemistry is influenced by land use in the surrounding watershed, particularly in complex urban landscapes, which are commonly subjected to an increase in material loadings. Because land use is rarely uniform, individual ecosystems embedded within the landscape may reflect varying water quality conditions. The Lake Merced system is composed of three lake basins with watersheds (surface area = 13 km2) residing entirely within the city of San Francisco, California. On nine occasions from January-June 1995 we sampled the two main lakes (North and South Lake Merced) within the system to evaluate their relative productivity and nutrient status. On each date, several physical-chemical conditions were measured, and nutrient enrichment bioassays were performed to evaluate the nutritional status of the phytoplankton (nitrogen (N) and phosphorus (P) enrichment in a 2 2 factorial experimental design). All the parameters tested except temperature were higher in the north lake compared with the south (pair-wise Wilcoxon Ranked sums), and common trophic state variables were more than 2-fold higher in the north lake. Phytoplankton growth in North Lake Merced was N-limited while growth in South Lake Merced was co-limited by N and P. In sum, our data indicate that differences among these lakes may be explained by simple volume differences between lakes (with the smaller North Lake Merced being more eutrophic), and heavy stocking of fishes to the north lake. Particulate nutrient ratios (N:P) were good indicators of phytoplankton nutritional status throughout the system, while N:P ratios based on total nutrient concentrations gave misleading results.
Cultural Eutrophication Trends in Three Southeastern Ontario Lakes: A Paleolimnological PerspectiveEuan D. Reavie; Kimberley E. Neill; Joanne L. Little; John P. SmolLake and Reservoir Management1040-23810743-8141221200644 - 58Cultural Eutrophication Trends in Three Southeastern Ontario Lakes: A Paleolimnological Perspective Three southeastern Ontario lakes have responded differently to human disturbances in their catchments over the past 150 years. Catchments of Round and Long lakes were once subjected to deforestation and apatite mining but currently have no local watershed disturbances. Meanwhile, Hambly Lake has been surrounded by residences since the 1950s. Subfossil chironomid head capsules and diatom valves were identified and enumerated in sediment cores from Hambly and Round lakes, and diatom remains were analyzed from Long Lake sediments. Quantitative reconstructions for chironomid-inferred average hypolimnetic dissolved oxygen (CIDO) and diatom inferred total phosphorus (DITP) were performed. Paleolimnological data indicated that Round Lake was subject to considerable human impacts in the late-1800s, with a dramatic shift from oligotrophic to mesotrophic and eutrophic diatom taxa and the onset of hypolimnetic anoxia. In the past 60 years (ca. 1945-present), Round Lake reverted to pre-anthropogenic settlement conditions in response to the cessation of human activities in the catchment. Long Lake microfossils revealed similar trends to those recorded in Round Lake, probably due to a similar disturbance history and its close geographic proximity. In contrast to the other two study sites, Hambly Lake was naturally mesotrophic prior to human settlement, and despite the development of numerous cottages and residences in the catchment, only minor shifts to slightly more eutrophic chironomid and diatom assemblages occurred. Higher nutrients and hypolimnetic anoxia appear to be natural conditions, and consequently little additional change occurred after the arrival of European settlers. This study illustrates the importance of obtaining long-term data for identifying background limnological conditions when assessing impacts and developing management plans.
Community Structure and Environmental Conditions in Florida Shallow Lakes Dominated by Submerged Aquatic VegetationBinhe Gu; Mark V. HoyerLake and Reservoir Management1040-23810743-81412142005403 - 410Community Structure and Environmental Conditions in Florida Shallow Lakes Dominated by Submerged Aquatic Vegetation Florida inland waters are dominated by shallow lakes, many of which support the growth of submerged aquatic vegetation (SAV). We examined the species composition and selected environmental variables of SAV-dominated lakes using data from the Florida LAKEWATCH program. Our analysis revealed eight genera with approximately 15 species of SAV among these shallow lakes, which range in size from <2-2,300 ha. The SAV community within each lake primarily consisted of a single or a few species. Utricularia and Hydrilla were the most common SAV genera found in these lakes. Many SAV species grew well in a wide range of water quality conditions, although biodiversity and biomass tended to increase with increasing alkalinity and calcium concentration. More SAV species were also found in lakes with higher pH and Secchi depth. On average, Ceratophyllum, Najas and Vallisneria dominated lakes with high total phosphorus (TP) concentrations (0.034-0.053 mg/L) while Chara, Utricularia, Potamogeton and Myriophyllum corresponded with relatively low TP concentrations (0.008-0.013 mg/L). However, there was a large overlap in nutrient concentrations in lakes dominated by different species.
Effects of Protective Limestone Treatment on Water Chemistry and Fisheries Management in Laurel Bed Lake, VirginiaDaniel M. Downey; Thomas M. HamptonLake and Reservoir Management1040-23810743-81412142005411 - 422Effects of Protective Limestone Treatment on Water Chemistry and Fisheries Management in Laurel Bed Lake, Virginia Dolomitic limestone additions to the acidic water of Laurel Bed Lake in southwestern Virginia have resulted in significant improvements in both the water quality and fishery. Pretreatment water quality showed the lake and its tributary to have high acidity with pH near or <5.0; negative acid neutralizing capacity (ANC) values; aluminum concentrations (AlT) > 150 μg/L; and low calcium to hydronium (Ca/H) ratios. The acidity is the result of atmospheric acid deposition, natural acidity from wetland origins and lack of carbonate-bearing minerals in the watershed. Limestone treatments have achieved target pH >6.5, ANC >100 μeq/L, AlT <60 μg/L and Ca/H >600. Iron and trace element concentrations have decreased. The dose-mass and frequency of limestone treatment to maintain circumneutral conditions has been found to be 150 tons introduced at two year intervals. Prior to implementation of this project, rock bass (Ambloplites rupestris) were overabundant and stunted (mean Total Length (TL) = 155 mm). The lake was drained, and the rock bass were removed. Stocked fingerling brook trout (Salvelinus fontinalis) survived and grew well following lake liming. Smallmouth bass (Micropterus dolomieu), stocked in response to the recurrence of rock bass, also performed well. An angler survey suggested that both species were important to the lake's fishery. The lake is now managed as a catch-and-release fishery for smallmouth bass and a put-and-grow fishery for brook trout.
Cyanobacterial Proliferation is a Recent Response to Eutrophication in Many Florida Lakes: A Paleolimnological AssessmentMelanie A. Riedinger-Whitmore; Thomas J. Whitmore; Joseph M. Smoak; Mark Brenner; Allen Moore; Jason Curtis; Claire L. SchelskeLake and Reservoir Management1040-23810743-81412142005423 - 435Cyanobacterial Proliferation is a Recent Response to Eutrophication in Many Florida Lakes: A Paleolimnological Assessment Cyanobacteria dominate many highly productive Florida lakes. Algal proliferation often is attributed to eutrophication during the last century, but it is poorly documented because Florida's water-quality monitoring programs became common only after 1980. We interpret paleolimnological data from the sediment cores of 6 productive lakes to determine when cyanobacterial proliferation first occurred, and whether it resulted from natural edaphic influence or from eutrophication caused by human activities. Major algal-pigment groups in sediments were analyzed using pigment-extraction and spectrophotometric techniques. Pigment profiles are compared with WACALIB-derived inferences for limnetic total-P, limnetic chlorophyll a, and trophic-state index values based on sedimented diatoms, and with stable isotope (δ13C & δ15N) signatures of organic matter. Cyanobacterial and algal proliferation increased during recent decades in 5 of the 6 study lakes in response to eutrophication. Two lakes demonstrated some evidence of recovery following nutrient-mitigation programs that reduced sewage and other point-source inputs. Five lakes showed intermittent to moderate cyanobacteria presence in the bottom portion of their cores because of edaphic nutrient supply or early watershed disturbance. One highly productive lake showed no evidence of eutrophication and demonstrated that dense cyanobacterial populations can occur naturally. Relationships were particularly strong among sedimented pigment profiles and diatom-inferred limnetic water-quality profiles. Although cyanobacteria have long-standing presence in some naturally productive Florida lakes, our studies suggest that algal proliferation in many lakes is both recent and abrupt in response to eutrophication. Paleolimnological methods are informative about the timing and causes of cyanobacterial appearance in regions where long-term water-quality data are lacking.
Landsat-based Remote Sensing of Lake Water Quality Characteristics, Including Chlorophyll and Colored Dissolved Organic Matter (CDOM)Patrick Brezonik; Kevin D. Menken; Marvin BauerLake and Reservoir Management1040-23810743-81412142005373 - 382Landsat-based Remote Sensing of Lake Water Quality Characteristics, Including Chlorophyll and Colored Dissolved Organic Matter (CDOM) Ground-based measurements on 15 Minnesota lakes with wide ranges of optical properties and Landsat TM data from the same lakes were used to evaluate the effect of humic color on satellite-inferred water quality conditions. Color (C440), as measured by absorbance at 440 nm, causes only small biases in estimates of Secchi disk transparency (SDT) from Landsat TM data, except at very high values (> ~ 300 chloroplatinate units, CPU). Similarly, when chlorophyll a (chl a) levels are moderate or high (> 10 μg/L), low-to-moderate levels of humic color have only a small influence on the relationship between SDT and chl a concentration, but it has a pronounced influence at high levels of C440 (e.g., > ~200 CPU). However, deviations from the general chl a-SDT relationship occur at much lower C440 values (~ 60 CPU) when chl a levels are low. Good statistical relationships were found between optical properties of lake water generally associated with algal abundance (SDT, chl a, turbidity) and measured brightness of various Landsat TM bands. The best relationships for chl a (based on R2 and absence of statistical outliers or lakes with large leverage) were combinations of bands 1, 2, or 4 with the band ratio 1:3 (R2 = 0.88). Although TM bands 1-4 individually or as simple ratios were poor predictors of C440, multiple regression analyses between ln(C440) and combinations of bands 1-4 and band ratios yielded several relationships with R2 ≥ 0.70, suggesting that C440 can be estimated with fair reliability from Landsat TM data.
Life-history Responses of Daphnia pulex with Exposure to Aluminum SulfateLouise A. Wold; Barry C. Moore; Nairanjana DasguptaLake and Reservoir Management1040-23810743-81412142005383 - 390Life-history Responses of Daphnia pulex with Exposure to Aluminum Sulfate Life table experiments with ten Daphnia clones were conducted to assess responses to three concentrations (0.05 mg 1-1 A1, 0.30 mg 1-1 A1, and 0.50 mg 1-1 A1) of aluminum sulfate (alum), reflecting a general range that might be encountered in lake restoration treatments. Alum is frequently employed for phosphorus inactivation in lake restoration and management applications. Experimental Daphnia clones originated from a lake currently being treated with alum, from a lake treated with alum over twenty years ago, and from a pond with no prior alum additions. When exposed to laboratory alum-conditioned media, clones from the lake with ongoing alum treatment exhibited higher age-specific survivorship, higher fecundity, and faster growth rates compared with clones having less recent or no prior exposure. Our results suggest the possibility that Daphnia may exhibit adaptive strategies that heighten survivorship and fecundity when exposed to sub-lethal chemical stresses. Results also indicate that clone origin and previous exposure to chemicals is an important consideration in Daphnia bioassays.
Introduction Pathways, Differential Survival of Adult and Larval Zebra Mussels (Dreissena polymorpha), and Possible Management Strategies, in an Adirondack Lake, Lake George, NYMarc E. Frischer; Brian R. McGrath; Andrew S. Hansen; Paul A. Vescio; Jane A. Wyllie; John Wimbush; Sandra A. Nierzwicki-BauerLake and Reservoir Management1040-23810743-81412142005391 - 402Introduction Pathways, Differential Survival of Adult and Larval Zebra Mussels (Dreissena polymorpha), and Possible Management Strategies, in an Adirondack Lake, Lake George, NY The introduction pathway and source of zebra mussel larvae into Lake George, NY were determined and a general bioassay was developed to assess the zebra mussel colonization risk of a water body. The presence of zebra mussel larvae (veligers), recruitment, and adults were monitored in Lake George from 1995-2003. All observations of zebra mussel veligers were at marinas, boat ramps, or areas heavily used by fishing boats. Models and observation suggest that human activity is the primary mechanism by which zebra mussels are transported overland. Although one small colony of zebra mussels was discovered during this period, no evidence was found of recruitment or permanent colonization by zebra mussels in Lake George. A series of bioassays to assess both larval and adult growth and survival was developed and indicated that Lake George water limited the survival of zebra mussel larvae but not of adults. These bioassays confirmed model predictions that zebra mussel recruitment is limited by the moderate water alkalinity in Lake George, but that adults were able to survive and grow. The unique water chemistry that limits zebra mussel colonization, and the close proximity of Lake George to other mussel-populated waters, make Lake George an ideal natural laboratory to study the introduction process of zebra mussel adults and/or larvae into a landlocked lake. Although zebra mussels have colonized the major waterways of Eastern North America, the establishment of zebra mussel populations in landlocked lakes is occurring much more slowly. Public outreach and education efforts that appear to aid in limiting the introduction of zebra mussels are also discussed.
Long-term Limnological Changes in Six Lakes with Differing Human Impacts from a Limestone Region in Southwestern Ontario, CanadaPetra Werner; Michelle Chaisson; John P. SmolLake and Reservoir Management1040-23810743-81412142005436 - 452Long-term Limnological Changes in Six Lakes with Differing Human Impacts from a Limestone Region in Southwestern Ontario, Canada Diatom-based paleolimnological techniques have been used to track limnological changes over the last ~150 years in six oligomesotrophic, primarily shallow, hardwater lakes in southwestern Ontario. Three of the six lakes are located in national parks and consequently have had little-to-no direct human impacts in their watersheds, with the exception of logging following initial European settlement (A.D. ~1850-1910). The paleolimnological indicators suggest that these activities have led to subtle-to-moderate eutrophication and possibly a reduction of macrophyte abundances. Additional subtle limnological changes have been occurring over the last century even in the undisturbed control lakes. The marked increase of Cyclotella comensis suggests that alkalinity levels may have increased ~1950-1980. The remaining three lakes experienced additional disturbances following the 19th century logging. For example, a campsite has been located on the shore of Cyprus Lake since 1968, but study results indicate this minor disturbance did not significantly alter water quality. In contrast, the last two of the six study lakes have experienced significantly more intense human impact and showed markedly different trophic histories. For example, the catchment of Chesley Lake was heavily developed for agriculture, the shoreline was densely populated with cottages and macrophytes were deliberately removed from the littoral zone. The paleolimnological data recorded a reduction of the water quality following these disturbances. Cage aquaculture has been ongoing in Lake Wolsey since 1983. Diatom changes in the lake's recent sediment are consistent with increased nutrient concentrations. Collectively, these paleolimnological data provide lake managers with important historical data from which trajectories of past limnological changes can be inferred and realistic mitigation targets can be identified.
Book ReviewsJames F. LaBountyLake and Reservoir Management1040-23810743-81412142005474Book Reviews
Book ReviewsJames F. LaBountyLake and Reservoir Management1040-23810743-81412142005474 - 475Book Reviews
Factors that Influence Phosphorus, Filamentous Cyanobacteria and Odor in McDaniel Lake, a Southwest Missouri Water Supply Reservoir, 1983–2002Norman W. YoungsteadtLake and Reservoir Management1040-23810743-81412142005453 - 464Factors that Influence Phosphorus, Filamentous Cyanobacteria and Odor in McDaniel Lake, a Southwest Missouri Water Supply Reservoir, 1983-2002 McDaniel Lake is a 1.12 km2 water supply reservoir subject to occasional taste and odor problems. This paper reviews data for 1983-2002, with a focus on summer, and uses regression analysis to identify predictors of lake phosphorus concentration, cyanobacteria filament concentration and odor production. Cattle were identified as the main source of excess tributary phosphorus, but lake phosphorus was significantly influenced by factors other than tributary phosphorus, including lake level, lake bottom temperature and wind. Likewise, cyanobacteria filament concentration was significantly influenced by factors other than lake phosphorus, including sunshine, air temperature and lake-bottom temperature. Odor (methylisoborneol plus geosmin) production was most strongly associated with high cyanobacteria filament counts and abundant sunshine.
Surface Seiche and Wind Set-up on Lake Okeechobee (Florida, USA) During Hurricanes Frances and JeanneMichael J. ChimneyLake and Reservoir Management1040-23810743-81412142005465 - 473Surface Seiche and Wind Set-up on Lake Okeechobee (Florida, USA) During Hurricanes Frances and Jeanne Hurricanes Frances and Jeanne (HF and HJ) passed over Lake Okeechobee, Fla., in September 2004. Strong winds produced a large surface seiche during both storms. The slope of the water surface reversed itself within 4 hrs as wind direction changed during HF, but shifted in only 2 hrs during HJ. The greatest water level difference was along the lake's north-south (N-S) axis during both storms (2.6 and 3.5 m, respectively). Differences between maximum wind set-up (storm surge) and set-down on the opposite shore indicated that the slope of the water surface was not symmetrical at the height of either storm. Using simple steady-state models, maximum wind set-up was forecast for opposing stations along the lake's N-S axis and compared to observed data and storm surge predictions by the SLOSH model. Steady-state model accuracy was not improved by using averaging periods >15 min in length or by lagging weather and water temperature data behind lake stage. Steady-state models calibrated to the data performed better than uncalibrated models. Prediction errors for maximum wind set-up during HF and HJ by SLOSH were comparable to errors in the steady-state models. While not a substitute for sophisticated hydrodynamic models like SLOSH and LOHM, properly calibrated steady-state models can provide lake managers with reasonable estimates of wind set-up. Future use of simple wind set-up models on Lake Okeechobee will require validation against data from other hurricanes.
A Simplified Assessment of Factors Controlling Phosphorus Loading from Oxygenated Sediments in a Very Shallow Eutrophic LakeNadia Kelton; Patricia Chow-FraserLake and Reservoir Management1040-23810743-81412132005223 - 230A Simplified Assessment of Factors Controlling Phosphorus Loading from Oxygenated Sediments in a Very Shallow Eutrophic Lake Factors controlling the release of bioavailable soluble reactive phosphorus (SRP) from sediments in very shallow lakes are not fully understood. Our approach involved relatively simple measurements of four factors affecting the calculation of internal phosphorus load: the number of sampling sites, sediment freezing, incubation temperature and oxic state in Cootes Paradise Marsh, now a very shallow (Z = 70 cm) eutrophic degraded urban lake in Ontario, Canada. Our results indicate that all of these factors need to be considered when attempting to estimate the internal phosphorus load of a shallow system. The total internal load of phosphorus in Cootes Paradise Marsh was 34% of the total loading (both internal and external), with diffusion from the sediment accounting for 23% of all phosphorus inputs. Large carp are now excluded from the lake and were estimated by difference to have contributed 23% to summer internal loading.
The Lake Okeechobee Water Quality Model (LOWQM) Enhancements, Calibration, Validation and AnalysisR. Thomas James; Victor J. Bierman Jr.; Michael J. Erickson; Scott C. HinzLake and Reservoir Management1040-23810743-81412132005231 - 260The Lake Okeechobee Water Quality Model (LOWQM) Enhancements, Calibration, Validation and Analysis The Lake Okeechobee Water Quality Model (LOWQM) was enhanced to more accurately simulate sediment-water phosphorus (P) dynamics by separating the organic P (OP) into four classes (readily degradable, moderately degradable, non-degradable and dissolved), and to more accurately simulate algal dynamics by representing the phytoplankton community with the three distinct major algal groups (cyanobacteria, diatoms and green algae) observed in the lake. The model was calibrated and validated to observed water column nutrient data, sediment nutrient measurements and biovolume data for cyanobacteria, diatoms, and green algae. Model predictions were consistent with experimental observations and indicated that net sediment inorganic P (IP) loads were twice the external TP loads and net sediment inorganic nitrogen (IN) loads were 0.64 times the external total N loads. However, because of organic nutrient and algal settling the lake sediments are an overall nutrient sink. Sensitivity analysis indicated that total algal carbon, algal groups and chlorophyll a were very sensitive to changing algal parameters, parameters affecting light, temperature and supply of IP to the water column. Nutrients were less sensitive for two reasons: 1) algae represent a small fraction of the total nutrient mass, 2) the large pools of sediment nutrients, with long turnover times, buffer changes in the water column. Sensitivity analysis pointed to three potential management options to improve lake water quality: dredging, chemical treatment of sediments and external load reduction. These options were previously considered in a large sediment management feasibility study, which concluded that the last option-load reduction-was the most viable.
Internal Nutrient Loads from Sediments in a Shallow, Subtropical LakeM. M. Fisher; K. R. Reddy; R. Thomas JamesLake and Reservoir Management1040-23810743-81412132005338 - 349Internal Nutrient Loads from Sediments in a Shallow, Subtropical Lake Fluxes of dissolved inorganic nitrogen, DIN, (as ammonia, NH4-N) and phosphorus (as dissolved reactive phosphorus, DRP) from the sediments to the water column of Lake Okeechobee were determined from two separate techniques: increases in nutrient concentration in the water column above intact cores and concentration gradients determined with pore water equilibrators. These fluxes were estimated from different sediment types within the lake (sand, peat, mud) and at two major inflows (Kissimmee River and Taylor Creek). DRP release from peat sediments was highest. Measurements in other sediments were not significantly different from each other. DRP flux to the lake was estimated as 326 Mt·yr-1 in 1989 and had increased to 472 Mt·yr-1 in 1999. Because of measurement variation, this increase was not statistically different. These estimates of internal DRP loads are greater than estimated external surface DRP loads that averaged 316 Mt·yr-1 from 1979-1988 and 258 Mt·yr-1 from 1989-1999. DIN flux was highest near Taylor Creek. There was no consistent pattern between sediment type and DIN flux. Internal loads of DIN were estimated in 1999 as 4,500 Mt·yr-1, which is greater than the external surface loads of DIN estimated for the period of 1989-1998, of 896 Mt·yr-1. Sediment oxygen demand measured in the cores was strongly correlated to DRP and DIN flux, indicating that these fluxes are largely a result of mineralization of organic material. This study indicates that sediment diffusive fluxes are a significant source of DRP and DIN to the lake water column.
Thermal Stratification and the Potential for Enhanced Phosphorus Release from the Sediments in Lake Okeechobee, USAA. J. Rodusky; B. Sharfstein; K-R. Jin; T. L. EastLake and Reservoir Management1040-23810743-81412132005330 - 337Thermal Stratification and the Potential for Enhanced Phosphorus Release from the Sediments in Lake Okeechobee, USA We inferred the potential importance of enhanced phosphorus (P) release from the sediments during periods of thermal stratification in Lake Okeechobee USA, a large, shallow, eutrophic lake. This was accomplished by determining the frequency and duration of thermal stratification, using monitoring data collected during 1997 and 1999, with multiparameter sondes, which were positioned at a weather platform in the center of the lake. We also monitored dissolved oxygen, pH, specific conductance, turbidity and redox potential, to assess if any relationships existed between these variables and thermal stratification. Thermal stratification was infrequent, documented for 42 and 74 total hours, and occurred for an extrapolated period of at least one hour on approximately 18 days or 5% of both years. Thermal stratification occurred almost exclusively during the summer (May - September), and was brief, typically lasting for one to six hours per event, although there was one event during 1999, where 49 continuous hours of thermal stratification were documented. Dissolved oxygen (DO) concentrations and redox potential (ORP) measurements collected 0.5 m above the sediment surface suggested that the top of the sediment may not have ever become anoxic and was rarely reducing. Chemical characteristics during periods of thermal stratification, compared to those considered favorable for P release based on previous Lake Okeechobee sediment studies, indicate that thermal stratification is usually insufficiently long for chemical conditions (anoxic or low DO and ORP) to develop above the sediment surface that would enable enhanced P release from the sediments.
Chlorophyll Response to Nutrients and Non-algal Seston in Missouri Reservoirs and Oxbow LakesJohn R. Jones; Matthew F. KnowltonLake and Reservoir Management1040-23810743-81412132005361 - 371Chlorophyll Response to Nutrients and Non-algal Seston in Missouri Reservoirs and Oxbow Lakes When unaggregated summer chlorophyll data (Chl) from 184 Missouri reservoirs are plotted against total phosphorus (TP) a 'bow' in the distribution develops among a group of points with low Chl:TP ratios (averaging <0.05). Low Chl:TP is mostly associated with turbid, nutrient-rich inflows in reservoirs across the entire trophic range. Non-algal seston (NAS) is our best metric of these inflows and is a co-variable in Chl-TP regressions. This influence is most prominent in years of high runoff and is distinctly seasonal, being most prevalent in early summer prior to full stratification. In late summer, inflows typically enter as subsurface density currents, and nitrogen accounts for more variation in Chl-TP than NAS. Neither variable, however, greatly influences the long-term relation between Chl and TP, which is linear, relatively consistent, and matches the global pattern. In several oxbow lakes, high NAS caused by sediment resuspension is a chronic condition; it seems neither light nor flushing greatly influence Chl: TP in these shallow systems, and values approximate the statewide average. Temporal variation in Chl:TP is demonstrated by daily samples (n=1676) from a single reservoir, with average variability, that covers about 94% of the statewide Chl and about a third of the TP range. The Chl-TP pattern in over half of Missouri reservoirs deviates somewhat from predictions based on cross-system regression models. Nonetheless, for 97% of the study reservoirs, long-term Chl is within a factor of two above or below model predictions, and most are within ±25%. Such differences are modest when compared to the temporal variation measured in an intensively studied reservoir.
Effects of Catchment Development on the Trophic Status of a Deep and a Shallow Reservoir in PortugalNuno-Gonçalo Matias; Maria-José BoavidaLake and Reservoir Management1040-23810743-81412132005350 - 360Effects of Catchment Development on the Trophic Status of a Deep and a Shallow Reservoir in Portugal Authors: Nuno-Gonalo Matiasa; Maria-Jos Boavidaa Abstract Although catchment nutrient flux regulation is considered vital for controlling eutrophication, direct measurement of runoff loads is difficult. Shallow eutrophic Divor and smaller deep mesotrophic Apartadura, with different catchment uses but almost identical lake-to-watershed area ratios, were studied. Ratios suggest both reservoirs should be oligo- to meso-trophic. Divor catchment intensive livestock farming opposes to subsistence farming in Apartadura catchment. Runoff coefficients indicated that cattle accounted for 75% of TP mass export in Divor but only about a third in Apartadura, where goats and sheep dominated. In both watersheds agriculture, including pasture, dominated TP export over woodland/brush cover. Because of the large agricultural component, people contributed <1% TP loading to Divor and 2-4% to Apartadura, reflecting population densities. Despite differences in watershed use and lake morphometry, reservoirs showed similar behaviour (summer hypolimnion anoxia, photic zone algal biomass). Transparent Apartadura was dominated by large algal particles and probably P-limited, while turbid Divor contained surplus phosphorus because of large amounts of fine suspended clay particles. The differences in mean depth, not watershed loading, apparently accounted for most of the differences in trophic state. Based on results, management actions to reduce eutrophication in the two reservoirs will differ. Divor drainage will primarily require better manure disposal and fertilizer use reduction but will probably not show trophic state improvement. Apartadura drainage will require diffuse-source P-control (constructed wetlands, riparian buffers) and it should respond by regaining an oxygenated hypolimnion. Stakeholder voluntary cooperation as well as modifying people's perceptions regarding water resources will be needed to comply with the legally binding EU Water Directives. Keywords: reservoir; catchment; in-lake processes; phosphorus; trophic state; land use View Full Text ArticleSubscribe Affiliation: a Departamento de Biologia Animal, Centro de Biologia Ambiental, Lisboa, Portugal DOI: 10.1080/07438140509354440 Published in: Lake and Reservoir Management Publication Frequency: 4 issues per year First Published on: 01 September 2005 Formats available: PDF (English) Although catchment nutrient flux regulation is considered vital for controlling eutrophication, direct measurement of runoff loads is difficult. Shallow eutrophic Divor and smaller deep mesotrophic Apartadura, with different catchment uses but almost identical lake-to-watershed area ratios, were studied. Ratios suggest both reservoirs should be oligo- to meso-trophic. Divor catchment intensive livestock farming opposes to subsistence farming in Apartadura catchment. Runoff coefficients indicated that cattle accounted for 75% of TP mass export in Divor but only about a third in Apartadura, where goats and sheep dominated. In both watersheds agriculture, including pasture, dominated TP export over woodland/brush cover. Because of the large agricultural component, people contributed <1% TP loading to Divor and 2-4% to Apartadura, reflecting population densities. Despite differences in watershed use and lake morphometry, reservoirs showed similar behaviour (summer hypolimnion anoxia, photic zone algal biomass). Transparent Apartadura was dominated by large algal particles and probably P-limited, while turbid Divor contained surplus phosphorus because of large amounts of fine suspended clay particles. The differences in mean depth, not watershed loading, apparently accounted for most of the differences in trophic state. Based on results, management actions to reduce eutrophication in the two reservoirs will differ. Divor drainage will primarily require better manure disposal and fertilizer use reduction but will probably not show trophic state improvement. Apartadura drainage will require diffuse-source P-control (constructed wetlands, riparian buffers) and it should respond by regaining an oxygenated hypolimnion. Stakeholder voluntary cooperation as well as modifying people's perceptions regarding water resources will be needed to comply with the legally binding EU Water Directives.
Characterization of Boulder Basin, Lake Mead, Nevada-Arizona, USA – Based on Analysis of 34 Limnological ParametersJames F. LaBounty; Noel M. BurnsLake and Reservoir Management1040-23810743-81412132005277 - 307Characterization of Boulder Basin, Lake Mead, Nevada-Arizona, USA - Based on Analysis of 34 Limnological Parameters Authors: James F. LaBountya; Noel M. Burnsb Abstract Lake Mead is a 66,000 ha-deep subtropical reservoir located on the Colorado River, Nevada-Arizona. This largest U.S. reservoir by volume is limnologically complex with four inflows, three basins, plus variable seasonal and annual operational patterns. This investigation is about the most downstream basin, Boulder Basin. Thirty-four measured parameters are used to describe limnological conditions of Boulder Basin, including Las Vegas Bay, from 1990-2004. Some assessments use data sets from May 2000 to April 2004; other assessments use more extensive data sets spanning up to 14 years of records. Selected parameters, trends, basic and reservoir-specific processes, and limnologically important relationships are illustrated and discussed. Boulder Basin is well stratified and ecologically complex due to the existence of two interflows. A super- to mesotrophic gradient exists from the nutrient rich inner basin, which has inflow from an urban tributary, to the middle and outer basins, which become progressively less productive. Secchi depth increases, chlorophyll (Chl a), plankton abundance, conductivity and total organic carbon (TOC) decrease going from the inner to outer basins. Lake Mead is strongly phosphorus (P)-limited and subject to a variety of algae blooms that depend on the presence and amounts of phosphorus. Due to ecological complexity, managing this resource is difficult and fraught with risk when conditions change. Along with the changing hydrologic conditions of the watershed that heavily influence Lake Mead, man-made products and toxin-producing algae are being introduced that need monitoring and management. Keywords: reservoir ecology; applied limnology; Lake Mead; phosphorus; nitrogen; Secchi depth; trophic index; data management tools View Full Text ArticleSubscribe Affiliations: a Southern Nevada Water Authority, Las Vegas, NV b Lakes Consulting, Devonport, New Zealand DOI: 10.1080/07438140509354435 Published in: Lake and Reservoir Management, Volume 21, Issue 3 September 2005 , pages 277 - 307 Publication Frequency: 4 issues per year First Published on: 01 September 2005 Formats available: PDF (English) Lake Mead is a 66,000 ha-deep subtropical reservoir located on the Colorado River, Nevada-Arizona. This largest U.S. reservoir by volume is limnologically complex with four inflows, three basins, plus variable seasonal and annual operational patterns. This investigation is about the most downstream basin, Boulder Basin. Thirty-four measured parameters are used to describe limnological conditions of Boulder Basin, including Las Vegas Bay, from 1990-2004. Some assessments use data sets from May 2000 to April 2004; other assessments use more extensive data sets spanning up to 14 years of records. Selected parameters, trends, basic and reservoir-specific processes, and limnologically important relationships are illustrated and discussed. Boulder Basin is well stratified and ecologically complex due to the existence of two interflows. A super- to mesotrophic gradient exists from the nutrient rich inner basin, which has inflow from an urban tributary, to the middle and outer basins, which become progressively less productive. Secchi depth increases, chlorophyll (Chl a), plankton abundance, conductivity and total organic carbon (TOC) decrease going from the inner to outer basins. Lake Mead is strongly phosphorus (P)-limited and subject to a variety of algae blooms that depend on the presence and amounts of phosphorus. Due to ecological complexity, managing this resource is difficult and fraught with risk when conditions change. Along with the changing hydrologic conditions of the watershed that heavily influence Lake Mead, man-made products and toxin-producing algae are being introduced that need monitoring and management.
Interaction of Nutrients and Turbidity in the Control of Phytoplankton in a Large Western Canadian Lake Prior to Major Watershed ImpoundmentsT. G. Northcote; F. R. Pick; D. B. Fillion; S. P. SalterLake and Reservoir Management1040-23810743-81412132005261 - 276Interaction of Nutrients and Turbidity in the Control of Phytoplankton in a Large Western Canadian Lake Prior to Major Watershed Impoundments Authors: T. G. Northcotea; F. R. Pickb; D. B. Fillion; S. P. Salter Abstract Kootenay Lake is a large (over 392 km2) fjord-type lake, part of the upper Columbia River Basin, which has undergone significant limnological changes due to a range of human activities over the past half century. We analyzed the limnological conditions of the lake during the mid 1960s, prior to major dam construction on its main tributaries. At that time, large volumes (25.4 km3 yr-1) of highly turbid (up to 180 JTU) but anthropogenically phosphate-enriched water entered the south end via the Kootenay River. This interacted with smaller volumes of less turbid and much lower nutrient waters entering from the Duncan River in the north and lateral lake drainages (15.6 and 9.8 km3 yr-1 respectively) to produce complex spatial and temporal differences in physical and chemical features (temperature, light penetration, ionic composition, pH, dissolved oxygen and nutrients) as well as in phytoplankton biomass, productivity and taxonomic composition. In the southern part of the lake, phytoplankton biomass, cell density and 14C uptake rates were severely depressed during late spring and summer by light limitation from incoming silt turbidity, in spite of high phosphate concentrations. In contrast, phytoplankton stock and production was elevated in the middle to northern parts where transparency was high. Experimental algal bioassays using filtered lake waters demonstrated that through this period nutrient (primarily phosphorus) limitation occurred in the northern but not in the southern parts of Kootenay Lake. Watershed impoundments during the 1970s homogenized and simplified this ecosystem. On-going efforts to rebuild fisheries through restoration of the pre-dam nutrient loading may not return Kootenay Lake to the spatial and temporal complexity that once existed. Keywords: watershed pre-dam conditions; phytoplankton biomass; primary productivity; light limitation; nutrient limitation; algal bioassays; mountain lake; Kootenay Lake View Full Text ArticleSubscribe Affiliations: a Dept. of Zoology, University of British Columbia, Vancouver, BC, Canada b Dept. of Biology, University of Ottawa, Ottawa, ON, Canada DOI: 10.1080/07438140509354434 Published in: Lake and Reservoir Management, Volume 21, Issue 3 September 2005 , pages 261 - 276 Publication Frequency: 4 issues per year First Published on: 01 September 2005 Formats available: PDF (English) Kootenay Lake is a large (over 392 km2) fjord-type lake, part of the upper Columbia River Basin, which has undergone significant limnological changes due to a range of human activities over the past half century. We analyzed the limnological conditions of the lake during the mid 1960s, prior to major dam construction on its main tributaries. At that time, large volumes (25.4 km3 yr-1) of highly turbid (up to 180 JTU) but anthropogenically phosphate-enriched water entered the south end via the Kootenay River. This interacted with smaller volumes of less turbid and much lower nutrient waters entering from the Duncan River in the north and lateral lake drainages (15.6 and 9.8 km3 yr-1 respectively) to produce complex spatial and temporal differences in physical and chemical features (temperature, light penetration, ionic composition, pH, dissolved oxygen and nutrients) as well as in phytoplankton biomass, productivity and taxonomic composition. In the southern part of the lake, phytoplankton biomass, cell density and 14C uptake rates were severely depressed during late spring and summer by light limitation from incoming silt turbidity, in spite of high phosphate concentrations. In contrast, phytoplankton stock and production was elevated in the middle to northern parts where transparency was high. Experimental algal bioassays using filtered lake waters demonstrated that through this period nutrient (primarily phosphorus) limitation occurred in the northern but not in the southern parts of Kootenay Lake. Watershed impoundments during the 1970s homogenized and simplified this ecosystem. On-going efforts to rebuild fisheries through restoration of the pre-dam nutrient loading may not return Kootenay Lake to the spatial and temporal complexity that once existed.
A Case History: Effects of Mixing Regime on Nutrient Dynamics and Community Structure in Third Sister Lake, Michigan During Late Winter and Early Spring 2003K. E. Judd; H. E. Adams; N. S. Bosch; J. M. Kostrzewski; C. E. Scott; B. M. Schultz; D. H. Wang; G. W. KlingLake and Reservoir Management1040-23810743-81412132005316 - 329A Case History: Effects of Mixing Regime on Nutrient Dynamics and Community Structure in Third Sister Lake, Michigan During Late Winter and Early Spring 2003 Authors: K. E. Judda; H. E. Adamsa; N. S. Boschb; J. M. Kostrzewskia; C. E. Scotta; B. M. Schultza; D. H. Wanga; G. W. Klinga Abstract We studied the winter to spring transition in Third Sister Lake (TSL), a small glacial lake in southeastern Michigan, to determine the effect of mixing regime on nutrient dynamics and community structure in an urban temperate lake. After ice-off, the oxycline was mixed downward from 3 to 6 m depth, resulting in addition of 5 mg m-2 P-SRP, 857 mg m-2 N-NH4+, and 400 mg m-2 N-NO3- to the epilimnion, but trapping 299 mg m-2 P-SRP, 7877 mg m-2 N-NH4+ and 36 mg m-2 N-NO3- in the bottom waters. Nutrients supplied by snow melt runoff (138 mg m-2 P-SRP, 430 mg m-2 N-NH4+, 596 mg m-2 N-NO3-) were an order of magnitude greater than rain event loads (0.13 mg m-2 P-SRP, 0.17 mg m-2 N-NH4+, and 1.05 mg m-2 N-NO3-) during the transition time from ice cover to open water. Reduced spring mixing did not have a large impact on N:P molar ratios, because external N:P ratios were low (7.5) compensating for reduced supply of P from the bottom waters. Bacterial production was greater in the hypolimnion than in the epilimnion, and mesocosm experiments showed that bacteria were P limited in the epilimnion but not in the hypolimnion. Total algal and zooplankton densities increased after ice-out, while Daphnia and Bosmina densities decreased. Increases in zooplankton grazing rates after ice-off were most dramatic in small-bodied zooplankton. Sediment core analysis showed that Asterionella relative abundance continues to increase, suggesting that the lake has become more brackish and oligotrophic. Our findings suggest that TSL has undergone a transition from dimictic to meromictic conditions, and that continued salt inputs have altered the structure and function of this ecosystem. Keywords: meromixis; nutrient dynamics; N:P ratios; productivity; road salt inputs; sediment core; snow melt; spring turnover View Full Text ArticleSubscribe Affiliations: a Dept. of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI b School of Natural Resources and Environment, University of Michigan, Ann Arbor, MI DOI: 10.1080/07438140509354437 Published in: Lake and Reservoir Management, Volume 21, Issue 3 September 2005 , pages 316 - 329 Publication Frequency: 4 issues per year First Published on: 01 September 2005 Formats available: PDF (English) We studied the winter to spring transition in Third Sister Lake (TSL), a small glacial lake in southeastern Michigan, to determine the effect of mixing regime on nutrient dynamics and community structure in an urban temperate lake. After ice-off, the oxycline was mixed downward from 3 to 6 m depth, resulting in addition of 5 mg m-2 P-SRP, 857 mg m-2 N-NH4+, and 400 mg m-2 N-NO3- to the epilimnion, but trapping 299 mg m-2 P-SRP, 7877 mg m-2 N-NH4+ and 36 mg m-2 N-NO3- in the bottom waters. Nutrients supplied by snow melt runoff (138 mg m-2 P-SRP, 430 mg m-2 N-NH4+, 596 mg m-2 N-NO3-) were an order of magnitude greater than rain event loads (0.13 mg m-2 P-SRP, 0.17 mg m-2 N-NH4+, and 1.05 mg m-2 N-NO3-) during the transition time from ice cover to open water. Reduced spring mixing did not have a large impact on N:P molar ratios, because external N:P ratios were low (7.5) compensating for reduced supply of P from the bottom waters. Bacterial production was greater in the hypolimnion than in the epilimnion, and mesocosm experiments showed that bacteria were P limited in the epilimnion but not in the hypolimnion. Total algal and zooplankton densities increased after ice-out, while Daphnia and Bosmina densities decreased. Increases in zooplankton grazing rates after ice-off were most dramatic in small-bodied zooplankton. Sediment core analysis showed that Asterionella relative abundance continues to increase, suggesting that the lake has become more brackish and oligotrophic. Our findings suggest that TSL has undergone a transition from dimictic to meromictic conditions, and that continued salt inputs have altered the structure and function of this ecosystem.
Factors Related to Angler Catch of Trophy Largemouth Bass in Texas ReservoirsRandall A. Myers; Micheal S. AllenLake and Reservoir Management1040-23810743-81412132005309 - 315Factors Related to Angler Catch of Trophy Largemouth Bass in Texas Reservoirs Authors: Randall A. Myersa; Micheal S. Allenb Abstract We used angler catch reports of largemouth bass Micropterus salmoides from Texas Parks and Wildlife Department angler recognition programs to determine if catch occurrence of trophy fish (≥5.9 kg) was greater in reservoirs stocked with fingerling Florida largemouth bass M. s. floridanus (FLMB) than in non-stocked reservoirs. We also compared trophy fish catch occurrence between reservoirs having the standard 356-mm minimum length harvest limit to reservoirs having a more restrictive length limit, and evaluated the relation of catch occurrence to reservoir age, surface area, shoreline development index (SDI), latitude, longitude, FLMB stocking frequency and density. Catch occurrence of trophy fish was significantly greater in FLMB-stocked reservoirs (29%) than in non-stocked reservoirs (4%). Probability of trophy largemouth bass catch occurrence in FLMB-stocked reservoirs increased with reservoir SDI, decreased with reservoir age, and was greater for reservoirs managed with special harvest regulations (high minimum length, protective slot, and no-harvest restrictions) than for reservoirs managed with the statewide standard minimum size. Our study indicated that introduction of FLMB into Texas reservoirs yielded greater trophy largemouth bass potential and suggested that differences in trophy potential among FLMB-stocked reservoirs are likely more a function of differing reservoir habitat than differences in FLMB stocking frequency and density. Keywords: trophy; largemouth bass; Texas; stocking; reservoir View Full Text ArticleSubscribe Affiliations: a Texas Parks and Wildlife Department, San Antonio, TX b Department of Fisheries and Aquatic Sciences, The University of Florida, Gainesville, FL DOI: 10.1080/07438140509354436 Published in: Lake and Reservoir Management, Volume 21, Issue 3 September 2005 , pages 309 - 315 Publication Frequency: 4 issues per year First Published on: 01 September 2005 Formats available: PDF (English) We used angler catch reports of largemouth bass Micropterus salmoides from Texas Parks and Wildlife Department angler recognition programs to determine if catch occurrence of trophy fish (≥5.9 kg) was greater in reservoirs stocked with fingerling Florida largemouth bass M. s. floridanus (FLMB) than in non-stocked reservoirs. We also compared trophy fish catch occurrence between reservoirs having the standard 356-mm minimum length harvest limit to reservoirs having a more restrictive length limit, and evaluated the relation of catch occurrence to reservoir age, surface area, shoreline development index (SDI), latitude, longitude, FLMB stocking frequency and density. Catch occurrence of trophy fish was significantly greater in FLMB-stocked reservoirs (29%) than in non-stocked reservoirs (4%). Probability of trophy largemouth bass catch occurrence in FLMB-stocked reservoirs increased with reservoir SDI, decreased with reservoir age, and was greater for reservoirs managed with special harvest regulations (high minimum length, protective slot, and no-harvest restrictions) than for reservoirs managed with the statewide standard minimum size. Our study indicated that introduction of FLMB into Texas reservoirs yielded greater trophy largemouth bass potential and suggested that differences in trophy potential among FLMB-stocked reservoirs are likely more a function of differing reservoir habitat than differences in FLMB stocking frequency and density.
Soft Sciences and the Hard Reality of Lake ManagementKent Thornton; Christina LaurinLake and Reservoir Management1040-23810743-81412122005203 - 208Soft Sciences and the Hard Reality of Lake Management Authors: Kent Thorntona; Christina Laurina Abstract Few would question that lake management requires multiple disciplines, such as fisheries biologists, limnologists, engineers, and hydrologists. Yet, watershed and lake management is fundamentally social in nature. Socioeconomic disciplines are essential if water and watershed research is to be policy and management relevant. Understanding the mental models not only of land owners and lake managers, but also the community and general public is critical if watershed and lake management practices are to be implemented and sustained. Where the mental models do not reflect factual information, social marketing approaches can be used to change both the fallacious mental model and the underlying behavior. The hard reality is that lake management practices can not be sustained without insight from the “soft sciences.” Keywords: interdisciplinary; mental model; social marketing; socioeconomic View Full Text ArticleSubscribe Affiliation: a FTN Associates, Ltd., Little Rock, AR DOI: 10.1080/07438140509354429 Published in: Lake and Reservoir Management Publication Frequency: 4 issues per year First Published on: 01 June 2005 Formats available: PDF (English) Few would question that lake management requires multiple disciplines, such as fisheries biologists, limnologists, engineers, and hydrologists. Yet, watershed and lake management is fundamentally social in nature. Socioeconomic disciplines are essential if water and watershed research is to be policy and management relevant. Understanding the mental models not only of land owners and lake managers, but also the community and general public is critical if watershed and lake management practices are to be implemented and sustained. Where the mental models do not reflect factual information, social marketing approaches can be used to change both the fallacious mental model and the underlying behavior. The hard reality is that lake management practices can not be sustained without insight from the “soft sciences.”
Internal Phosphorus Loading in Shallow Lakes: Importance and ControlEugene B. Welch; G. Dennis CookeLake and Reservoir Management1040-23810743-81412122005209 - 217Internal Phosphorus Loading in Shallow Lakes: Importance and Control Authors: Eugene B. Welcha; G. Dennis Cookeb Abstract Decreasing the algal biomass and increasing transparency in shallow, unstratified lakes is usually more difficult than for deep, stratified lakes. Eutrophic unstratified lakes (or shallow, stratified lakes susceptible to metalimnion erosion) have typically responded slowly to reduced external nutrient loading, usually because of longevity of internal loading. That is because sediment-released nutrients (especially phosphorus) readily enter the trophogenic zone of shallow lakes during the growing season and result in high lake concentrations. In stratified lakes, metalimnia may serve as barriers to phosphorus transport into the trophogenic zone. Although the whole water column in shallow lakes is usually aerobic, several mechanisms can combine to produce relatively high sediment phosphorus release rates in these lakes. These include: 1) wind resuspension and bioturbation, combined with high pH or low Fe/P ratio that maintains high P solubility, 2) periodic anoxia and reducing conditions promoted by calm, warm weather, and 3) macro-phyte senescence. Attempts to reduce algal biomass by controlling internal phosphorus loading have often been effective. Keywords: phosphorus; internal loading; control; shallow lakes View Full Text ArticleSubscribe Affiliations: a Department of Civil Engineering, University of Washington, Seattle, WA b Department of Biological Sciences, Water Resources Research Institute, Kent State University, Kent, OH DOI: 10.1080/07438140509354430 Published in: Lake and Reservoir Management, Volume 21, Issue 2 June 2005 , pages 209 - 217 Publication Frequency: 4 issues per year First Published on: 01 June 2005 Formats available: PDF (English) Decreasing the algal biomass and increasing transparency in shallow, unstratified lakes is usually more difficult than for deep, stratified lakes. Eutrophic unstratified lakes (or shallow, stratified lakes susceptible to metalimnion erosion) have typically responded slowly to reduced external nutrient loading, usually because of longevity of internal loading. That is because sediment-released nutrients (especially phosphorus) readily enter the trophogenic zone of shallow lakes during the growing season and result in high lake concentrations. In stratified lakes, metalimnia may serve as barriers to phosphorus transport into the trophogenic zone. Although the whole water column in shallow lakes is usually aerobic, several mechanisms can combine to produce relatively high sediment phosphorus release rates in these lakes. These include: 1) wind resuspension and bioturbation, combined with high pH or low Fe/P ratio that maintains high P solubility, 2) periodic anoxia and reducing conditions promoted by calm, warm weather, and 3) macro-phyte senescence. Attempts to reduce algal biomass by controlling internal phosphorus loading have often been effective.
Applicability of Littoral Food-web Biomanipulation for Lake Management Purposes: Snails, Macrophytes, and Water Transparency in Northeast Ohio Shallow LakesPaola LombardoLake and Reservoir Management1040-23810743-81412122005186 - 202Applicability of Littoral Food-web Biomanipulation for Lake Management Purposes: Snails, Macrophytes, and Water Transparency in Northeast Ohio Shallow Lakes Author: Paola Lombardoa Abstract Seven shallow-to-intermediate-depth, meso-eutrophic lakes in northeast Ohio were surveyed July-August 1998 to evaluate a macrophyte-based littoral food-web (and its possible manipulation) role in increasing or maintaining water transparency. Macrophyte and periphyton growth were determined from pre-weighed C. demersum sprigs and biomass developed on glass tiles, respectively; littoral snail densities were estimated from assemblages in large-mesh cages at 1-m depth. Other variables were monitored weekly in situ. Lakes were generally phosphorus (P)-limited, but differed significantly in perceived state (turbid, stable or unstable clear-water), water transparency (SD), total phosphorus (TP) and chlorophyll a concentration (chla), vegetation cover (VC), snail density, sprig growth and periphyton biomass. The most richly vegetated lake was also the most stable (seasonally and long-term) clear-water lake, but midsummer SD was more strongly correlated with watershed:lake surface area. C. demersum growth was negatively correlated with periphyton biomass; meristem production was lower in turbid lakes, but was influenced by TP. Snail abundance tended to follow food (periphyton) and substrate (VC) availability, but was lower in crayfish-present lakes. Correlations between lake-describing variables were nonlinear with frequent outliers. When integrated with information from the literature, the results suggest that littoral food-web biomanipulation may be employed as a management technique in some cases. More often, macrophytes and the macrophyte-driven, snail-mediated clear-water stable state may (re)establish naturally in suitable lakes after conditions are brought above a “threshold” for plant growth. Frequent exceptions in observed patterns in this study and elsewhere suggest that applicability of littoral food-web biomanipulation should be evaluated on a case-by-case basis. Keywords: littoral food webs; macrophytes; water transparency; gastropods; periphyton; shallow lakes; lake management; alternate stable states View Full Text ArticleSubscribe Affiliation: a Department of Genetics and Molecular Biology, La Sapienza State University of Rome, Rome, Italy DOI: 10.1080/07438140509354428 Published in: Lake and Reservoir Management, Volume 21, Issue 2 June 2005 , pages 186 - 202 Publication Frequency: 4 issues per year First Published on: 01 June 2005 Formats available: PDF (English) Seven shallow-to-intermediate-depth, meso-eutrophic lakes in northeast Ohio were surveyed July-August 1998 to evaluate a macrophyte-based littoral food-web (and its possible manipulation) role in increasing or maintaining water transparency. Macrophyte and periphyton growth were determined from pre-weighed C. demersum sprigs and biomass developed on glass tiles, respectively; littoral snail densities were estimated from assemblages in large-mesh cages at 1-m depth. Other variables were monitored weekly in situ. Lakes were generally phosphorus (P)-limited, but differed significantly in perceived state (turbid, stable or unstable clear-water), water transparency (SD), total phosphorus (TP) and chlorophyll a concentration (chla), vegetation cover (VC), snail density, sprig growth and periphyton biomass. The most richly vegetated lake was also the most stable (seasonally and long-term) clear-water lake, but midsummer SD was more strongly correlated with watershed:lake surface area. C. demersum growth was negatively correlated with periphyton biomass; meristem production was lower in turbid lakes, but was influenced by TP. Snail abundance tended to follow food (periphyton) and substrate (VC) availability, but was lower in crayfish-present lakes. Correlations between lake-describing variables were nonlinear with frequent outliers. When integrated with information from the literature, the results suggest that littoral food-web biomanipulation may be employed as a management technique in some cases. More often, macrophytes and the macrophyte-driven, snail-mediated clear-water stable state may (re)establish naturally in suitable lakes after conditions are brought above a “threshold” for plant growth. Frequent exceptions in observed patterns in this study and elsewhere suggest that applicability of littoral food-web biomanipulation should be evaluated on a case-by-case basis.
Alum:Redox-Sensitive Phosphorus Ratio Considerations and Uncertainties in the Estimation of Alum Dosage to Control Sediment PhosphorusWilliam F. JamesLake and Reservoir Management1040-23810743-81412122005159 - 164Alum:Redox-Sensitive Phosphorus Ratio Considerations and Uncertainties in the Estimation of Alum Dosage to Control Sediment Phosphorus Author: William F. Jamesa Abstract Alum dosage requirements to immobilize loosely-bound and iron-bound sediment phosphorus (P) fractions (i.e., redox-sensitive P fractions) in the surface sediments of eutrophic, Squaw Lake, Wisconsin, were determined using alum assay procedures developed by Rydin and Welch (1999). Since the lake exhibits a low buffering capacity (alkalinity = 25 mg Ca L-1), an alkalinity-based calculation could not be used to estimate alum dosage. Redox-sensitive sediment P fractions of surficial sediments, which represented 44% of the inorganic sediment P, were depleted by greater than 90% at an alum (as Al):redox-sensitive P binding ratio of ~ 100:1. Our results suggest that a higher dosage of alum, based on a higher alum:redox-sensitive P binding ratio requirement, is necessary to achieve effective control of sediment P in this lake. However, uncertainties still exist in the calculation of an alum dosage based on redox-sensitive sediment P concentration. More research is needed to validate optimal alum:redox-sensitive P binding ratios for use in sediment P-based alum dosage calculations. Criteria for estimating the layer of profundal sediment (i.e., the volume of redox-sensitive sediment P or the active layer of sediment contributing to diffusive P flux) to treat is also needed in order to estimate a cost-effective alum dosage for reducing internal P loading. Keywords: alum; internal P loading; phosphorus; sediment; soft-water lake View Full Text ArticleSubscribe Affiliation: a U.S. Army Engineer Research and Development Center, Eau Galle Aquatic Ecology Laboratory, Spring Valley, WI DOI: 10.1080/07438140509354425 Published in: Lake and Reservoir Management, Volume 21, Issue 2 June 2005 , pages 159 - 164 Publication Frequency: 4 issues per year First Published on: 01 June 2005 Formats available: PDF (English) Alum dosage requirements to immobilize loosely-bound and iron-bound sediment phosphorus (P) fractions (i.e., redox-sensitive P fractions) in the surface sediments of eutrophic, Squaw Lake, Wisconsin, were determined using alum assay procedures developed by Rydin and Welch (1999). Since the lake exhibits a low buffering capacity (alkalinity = 25 mg Ca L-1), an alkalinity-based calculation could not be used to estimate alum dosage. Redox-sensitive sediment P fractions of surficial sediments, which represented 44% of the inorganic sediment P, were depleted by greater than 90% at an alum (as Al):redox-sensitive P binding ratio of ~ 100:1. Our results suggest that a higher dosage of alum, based on a higher alum:redox-sensitive P binding ratio requirement, is necessary to achieve effective control of sediment P in this lake. However, uncertainties still exist in the calculation of an alum dosage based on redox-sensitive sediment P concentration. More research is needed to validate optimal alum:redox-sensitive P binding ratios for use in sediment P-based alum dosage calculations. Criteria for estimating the layer of profundal sediment (i.e., the volume of redox-sensitive sediment P or the active layer of sediment contributing to diffusive P flux) to treat is also needed in order to estimate a cost-effective alum dosage for reducing internal P loading.
Biologically Labile and Refractory Phosphorus Loads from the Agriculturally-Managed Upper Eau Galle River Watershed, WisconsinWilliam F. James; John W. BarkoLake and Reservoir Management1040-23810743-81412122005165 - 173Biologically Labile and Refractory Phosphorus Loads from the Agriculturally-Managed Upper Eau Galle River Watershed, Wisconsin Authors: William F. Jamesa; John W. Barkoa Abstract Fractionation techniques were used to quantify various biologically labile (i.e., directly available for biological uptake or subject to recycling pathways) and refractory (i.e., biologically unavailable and subject to burial) particulate and soluble phosphorus (P) forms along the longitudinal axis of the agriculturally-managed Upper Eau Galle River watershed in west-central Wisconsin. P loading increased as a function of increasing distance from the river's headwaters. However, areal P export rates were similar longitudinally, indicating a relatively homogeneous land-use mosaic throughout the watershed. P loads were composed of predominantly biologically labile constituents (i.e., 79%), with soluble P forms (i.e., soluble reactive and unreactive P) accounting for 49% and labile particulate P forms (i.e., loosely-bound PP, iron-bound PP, and labile organic/polyphosphate PP) accounting for 30% of the P load. Soluble P forms are either directly available for biological uptake or can be converted to available forms through enzymatic (i.e., alkaline phosphatase) reactions. Deposition and retention of loosely-bound and iron-bound PP in the receiving impoundment, Eau Galle Reservoir, can become an important source of internal P loading via eH and pH chemical reactions. Suspended solids loads also exhibited a high equilibrium P concentration (i.e., EPC > 0.10 mg L-1) that was similar to flow-weighted soluble reactive P concentrations in the river, suggesting equilibrium control of soluble P as loads entered the reservoir. The high EPC and a linear adsorption coefficient approaching 1000 L kg-1 indicated that binding sites of eroded soils in the runoff were enriched with P due to soil nutrient management. Our results indicated that transformations, transport, and fate of biologically labile PP, as well as soluble P, need to be considered in load reduction management to eutrophic receiving waters. Keywords: Adsorption-desorption; biological phosphorus availability; equilibrium phosphorus concentration; labile phosphorus forms; loading; phosphorus; refractory phosphorus forms; runoff; watershed View Full Text ArticleSubscribe Affiliation: a U.S. Army Engineer Research and Development Center, Eau Galle Aquatic Ecology Laboratory, Spring Valley, WI DOI: 10.1080/07438140509354426 Published in: Lake and Reservoir Management, Volume 21, Issue 2 June 2005 , pages 165 - 173 Publication Frequency: 4 issues per year First Published on: 01 June 2005 Formats available: PDF (English) Fractionation techniques were used to quantify various biologically labile (i.e., directly available for biological uptake or subject to recycling pathways) and refractory (i.e., biologically unavailable and subject to burial) particulate and soluble phosphorus (P) forms along the longitudinal axis of the agriculturally-managed Upper Eau Galle River watershed in west-central Wisconsin. P loading increased as a function of increasing distance from the river's headwaters. However, areal P export rates were similar longitudinally, indicating a relatively homogeneous land-use mosaic throughout the watershed. P loads were composed of predominantly biologically labile constituents (i.e., 79%), with soluble P forms (i.e., soluble reactive and unreactive P) accounting for 49% and labile particulate P forms (i.e., loosely-bound PP, iron-bound PP, and labile organic/polyphosphate PP) accounting for 30% of the P load. Soluble P forms are either directly available for biological uptake or can be converted to available forms through enzymatic (i.e., alkaline phosphatase) reactions. Deposition and retention of loosely-bound and iron-bound PP in the receiving impoundment, Eau Galle Reservoir, can become an important source of internal P loading via eH and pH chemical reactions. Suspended solids loads also exhibited a high equilibrium P concentration (i.e., EPC > 0.10 mg L-1) that was similar to flow-weighted soluble reactive P concentrations in the river, suggesting equilibrium control of soluble P as loads entered the reservoir. The high EPC and a linear adsorption coefficient approaching 1000 L kg-1 indicated that binding sites of eroded soils in the runoff were enriched with P due to soil nutrient management. Our results indicated that transformations, transport, and fate of biologically labile PP, as well as soluble P, need to be considered in load reduction management to eutrophic receiving waters.
The Phosphorus Mass Balance of Lake Okeechobee, Florida: Implications for Eutrophication ManagementKarl E. Havens; R. Thomas JamesLake and Reservoir Management1040-23810743-81412122005139 - 148The Phosphorus Mass Balance of Lake Okeechobee, Florida: Implications for Eutrophication Management Authors: Karl E. Havensa; R. Thomas Jamesb Abstract A phosphorus (P) mass balance was developed for Lake Okeechobee, Florida (USA) for the period 1973 to 2002. During those 30 years, yearly P inputs averaged 499 metric tons, outputs averaged 174 metric tons, and there was a 297 metric ton ·y-1 net sink, attributed to sediment accrual. Yearly P loads were highly variable, ranging from <200 to >900 metric tons, and there was a strong positive relationship between yearly load and inflow volume (r2 = 0.73). There was no long-term trend in P loading to the lake, but the total P concentration of inflow water displayed a historic trend that was independent of inflow volume, perhaps related to P control programs in the watershed. Inflow total P increased from 150 to >200 μg·L-1 in the 1970s when land use was intensified but management programs generally were absent, but declined in the 1980s and 1990s (to ~150 μg·L-1), coincident with various P control programs. Inflow total P concentrations displayed no trend after the early 1990s, although there was considerable year-to-year variability. Lake water total P concentrations increased during the 1970s, stabilized in the 1980s and early 1990s, and increased in recent years, possibly due to sediment saturation with P. There was no significant relationship between lake water total P concentration and mean depth, contradicting earlier reports based on shorter (10 and 20-y) periods of record. The difference between annual average inflow and lake water total P declined from near 150 μg·L-1 in the 1970s to <50 μg·L-1 in recent years, and the net sedimentation coefficient declined from near 2.0 to just above zero. These trends indicate a decreasing capacity of the lake to assimilate P. Two features noted here - (1) potential of the watershed to export large amounts of P rich water in certain years, and (2) lack of P assimilative capacity of the lake - indicate that the ecosystem is at risk for continued and perhaps worsened eutrophication symptoms under current P loading conditions. Keywords: phosphorus; mass balance; shallow lakes; Lake Okeechobee View Full Text ArticleSubscribe Affiliations: a Department of Fisheries and Aquatic Sciences, University of Florida, Gainesville, FL b South Florida Water Management District, West Palm Beach, FL DOI: 10.1080/07438140509354423 Published in: Lake and Reservoir Management, Volume 21, Issue 2 June 2005 , pages 139 - 148 Publication Frequency: 4 issues per year First Published on: 01 June 2005 Formats available: PDF (English) A phosphorus (P) mass balance was developed for Lake Okeechobee, Florida (USA) for the period 1973 to 2002. During those 30 years, yearly P inputs averaged 499 metric tons, outputs averaged 174 metric tons, and there was a 297 metric ton ·y-1 net sink, attributed to sediment accrual. Yearly P loads were highly variable, ranging from <200 to >900 metric tons, and there was a strong positive relationship between yearly load and inflow volume (r2 = 0.73). There was no long-term trend in P loading to the lake, but the total P concentration of inflow water displayed a historic trend that was independent of inflow volume, perhaps related to P control programs in the watershed. Inflow total P increased from 150 to >200 μg·L-1 in the 1970s when land use was intensified but management programs generally were absent, but declined in the 1980s and 1990s (to ~150 μg·L-1), coincident with various P control programs. Inflow total P concentrations displayed no trend after the early 1990s, although there was considerable year-to-year variability. Lake water total P concentrations increased during the 1970s, stabilized in the 1980s and early 1990s, and increased in recent years, possibly due to sediment saturation with P. There was no significant relationship between lake water total P concentration and mean depth, contradicting earlier reports based on shorter (10 and 20-y) periods of record. The difference between annual average inflow and lake water total P declined from near 150 μg·L-1 in the 1970s to <50 μg·L-1 in recent years, and the net sedimentation coefficient declined from near 2.0 to just above zero. These trends indicate a decreasing capacity of the lake to assimilate P. Two features noted here - (1) potential of the watershed to export large amounts of P rich water in certain years, and (2) lack of P assimilative capacity of the lake - indicate that the ecosystem is at risk for continued and perhaps worsened eutrophication symptoms under current P loading conditions.
Toward Integration in Reservoir ManagementRobert H. KennedyLake and Reservoir Management1040-23810743-81412122005128 - 138Toward Integration in Reservoir Management Author: Robert H. Kennedya Abstract Reservoirs are engineered features of hydrologic landscapes with characteristics defined by engineering design criteria. Many of these characteristics impact water quality. Reservoir management has historically been dictated by water control requirements; environment and water quality have been secondary considerations. Management approaches that address inputs of nutrients, sediment and organic material as root causes of eutrophication have been difficult to implement due to the location of reservoirs in large, complex watersheds. Costly engineering solutions that reduce symptoms of problems rather than address their cause are favored over watershed-based approaches applied to smaller natural lakes. To be successful, future management initiatives will require more integrative approaches that recognize reservoirs as integral components of watersheds and river basins. Understanding interactions between engineering practice and water quality fosters the development and implementation of effective management approaches that address environmental and water quality concerns as well as water quantity. Keywords: reservoir; water quality; reservoir management; reservoir operation View Full Text ArticleSubscribe Affiliation: a European Research Office, US Army Engineer Research and Development Center, London, United Kingdom DOI: 10.1080/07438140509354422 Published in: Lake and Reservoir Management, Volume 21, Issue 2 June 2005 , pages 128 - 138 Publication Frequency: 4 issues per year First Published on: 01 June 2005 Formats available: PDF (English) Reservoirs are engineered features of hydrologic landscapes with characteristics defined by engineering design criteria. Many of these characteristics impact water quality. Reservoir management has historically been dictated by water control requirements; environment and water quality have been secondary considerations. Management approaches that address inputs of nutrients, sediment and organic material as root causes of eutrophication have been difficult to implement due to the location of reservoirs in large, complex watersheds. Costly engineering solutions that reduce symptoms of problems rather than address their cause are favored over watershed-based approaches applied to smaller natural lakes. To be successful, future management initiatives will require more integrative approaches that recognize reservoirs as integral components of watersheds and river basins. Understanding interactions between engineering practice and water quality fosters the development and implementation of effective management approaches that address environmental and water quality concerns as well as water quantity.
PrefaceRobert H. Kennedy; Spencer A. PetersonLake and Reservoir Management1040-23810743-81412122005127Preface Authors: Robert H. Kennedy; Spencer A. Peterson View Full Text ArticleSubscribe DOI: 10.1080/07438140509354421 Published in: Lake and Reservoir Management, Volume 21, Issue 2 June 2005 , page 127 Publication Frequency: 4 issues per year First Published on: 01 June 2005 Formats available: PDF (English)
Development of Regional Nutrient Criteria and Implications for States and the Regulated CommunityNancy PalmstromLake and Reservoir Management1040-23810743-81412122005174 - 185Development of Regional Nutrient Criteria and Implications for States and the Regulated Community Author: Nancy Palmstroma Abstract Nutrient enrichment is a major threat to many of the nation's surface waters. The U.S. Environmental Protection Agency (EPA) has made development of nutrient criteria to protect the uses and functions of these waters a national priority (EPA 1998). Establishment of these nutrient criteria must take into account regional differences and waterbody characteristics. EPA has published related guidance documents for development of criteria, as well as ecoregional nutrient criteria documents for lakes and reservoirs and rivers and streams. Work is underway in states across the United States to gather data and develop regional nutrient criteria. The development of a database for EPA Region 3 to support regional nutrient criteria development is discussed, and use of the database for criteria development is demonstrated. Potential implications for states, River Basin Commissions (RBCs), tribes and wastewater dischargers are also addressed. Keywords: nutrient criteria; nutrients; water quality criteria View Full Text ArticleSubscribe Affiliation: a ENSR International, Piscataway, NJ DOI: 10.1080/07438140509354427 Published in: Lake and Reservoir Management, Volume 21, Issue 2 June 2005 , pages 174 - 185 Publication Frequency: 4 issues per year First Published on: 01 June 2005 Formats available: PDF (English) Nutrient enrichment is a major threat to many of the nation's surface waters. The U.S. Environmental Protection Agency (EPA) has made development of nutrient criteria to protect the uses and functions of these waters a national priority (EPA 1998). Establishment of these nutrient criteria must take into account regional differences and waterbody characteristics. EPA has published related guidance documents for development of criteria, as well as ecoregional nutrient criteria documents for lakes and reservoirs and rivers and streams. Work is underway in states across the United States to gather data and develop regional nutrient criteria. The development of a database for EPA Region 3 to support regional nutrient criteria development is discussed, and use of the database for criteria development is demonstrated. Potential implications for states, River Basin Commissions (RBCs), tribes and wastewater dischargers are also addressed.
Ecosystem RehabilitationG. Dennis CookeLake and Reservoir Management1040-23810743-81412122005218 - 221Ecosystem Rehabilitation Author: G. Dennis Cookea Abstract Restoration of damaged or extirpated aquatic and terrestrial ecosystems has been proposed as one means of meeting Clean Water Act goals, and as a way to reduce further ecological deficits and economic losses. However, restoration means a return to pre-disturbance conditions and relies on historic landscapes or ecosystems as models. It is the most demanding of management paradigms and implies complete re-creation of a system equivalent to the model. Restoration represents the extreme on a continuum of management protocols and is valuable as an ideal. In most cases, it is impractical, uncalled for, or even impossible. Rehabilitation is the repair and replacement of essential ecosystem structures and functions in the context of ecoregional attainability in order to achieve specified objectives. It is analogous to medical rehabilitation and emphasizes return to an achievable resemblance of prior conditions and makes no pretense of accomplishing absolute authenticity. It is a process in which many ecologists are engaged. It excludes activities solely oriented to human centered needs, such as spraying and cleanups. Damage and loss of freshwater ecosystems are apparent. The consequences are just beginning to be understood. I urge the establishment of ecologically coherent Federal rehabilitation programs. Keywords: ecosystem rehabilitation; restoration View Full Text ArticleSubscribe Affiliation: a Department of Biological Sciences, Water Resources Research Institute, Kent State University, Kent, OH DOI: 10.1080/07438140509354431 Published in: Lake and Reservoir Management, Volume 21, Issue 2 June 2005 , pages 218 - 221 Publication Frequency: 4 issues per year First Published on: 01 June 2005 Formats available: PDF (English) Restoration of damaged or extirpated aquatic and terrestrial ecosystems has been proposed as one means of meeting Clean Water Act goals, and as a way to reduce further ecological deficits and economic losses. However, restoration means a return to pre-disturbance conditions and relies on historic landscapes or ecosystems as models. It is the most demanding of management paradigms and implies complete re-creation of a system equivalent to the model. Restoration represents the extreme on a continuum of management protocols and is valuable as an ideal. In most cases, it is impractical, uncalled for, or even impossible. Rehabilitation is the repair and replacement of essential ecosystem structures and functions in the context of ecoregional attainability in order to achieve specified objectives. It is analogous to medical rehabilitation and emphasizes return to an achievable resemblance of prior conditions and makes no pretense of accomplishing absolute authenticity. It is a process in which many ecologists are engaged. It excludes activities solely oriented to human centered needs, such as spraying and cleanups. Damage and loss of freshwater ecosystems are apparent. The consequences are just beginning to be understood. I urge the establishment of ecologically coherent Federal rehabilitation programs.
Wind Control on Water Quality in Shallow, Hypereutrophic Upper Klamath Lake, OregonJacob Kann; Eugene B. WelchLake and Reservoir Management1040-23810743-81412122005149 - 158Wind Control on Water Quality in Shallow, Hypereutrophic Upper Klamath Lake, Oregon Authors: Jacob Kanna; Eugene B. Welchbc Abstract Large blooms of cyanobacteria, primarily Aphanizomenon flos-aquae, are linked to poor water quality in Upper Klamath Lake, Oregon. High pH and high un-ionized ammonia concentrations are associated with the blooms when algae are actively growing, followed by low dissolved oxygen (DO) conditions when the blooms decline in mid- to late summer. Over a 12-year study period, algal biomass was strongly related to total phosphorus concentration (TP) and pH. Minimum water column DO was strongly related to net negative changes (i.e., declines) in algal biomass during July and August. The severity of both low DO and high ammonia was positively related to water column stability, which was dependent on wind speed. Bloom dynamics, coupled with climate, dominated year-to-year variability in water quality dynamics in Upper Klamath Lake. These data provide the empirical basis for previous research linking high mortalities of endangered sucker species with years of low wind and high water column stability. Keywords: wind mixing; water column stability; water quality; blue-green algal blooms; fish kills View Full Text ArticleSubscribe Affiliations: a Aquatic Ecosystem Sciences, LLC, Ashland, OR b Department of Civil and Environmental Engineering, University of Washington, Seattle, WA c Tetra Tech, Inc., Seattle, WA DOI: 10.1080/07438140509354424 Published in: Lake and Reservoir Management, Volume 21, Issue 2 June 2005 , pages 149 - 158 Publication Frequency: 4 issues per year First Published on: 01 June 2005 Formats available: PDF (English) Large blooms of cyanobacteria, primarily Aphanizomenon flos-aquae, are linked to poor water quality in Upper Klamath Lake, Oregon. High pH and high un-ionized ammonia concentrations are associated with the blooms when algae are actively growing, followed by low dissolved oxygen (DO) conditions when the blooms decline in mid- to late summer. Over a 12-year study period, algal biomass was strongly related to total phosphorus concentration (TP) and pH. Minimum water column DO was strongly related to net negative changes (i.e., declines) in algal biomass during July and August. The severity of both low DO and high ammonia was positively related to water column stability, which was dependent on wind speed. Bloom dynamics, coupled with climate, dominated year-to-year variability in water quality dynamics in Upper Klamath Lake. These data provide the empirical basis for previous research linking high mortalities of endangered sucker species with years of low wind and high water column stability.
Influences of Lake Level Changes on Reservoir Water Clarity in Allatoona Lake, GeorgiaJoseph M. Dirnberger; Jason WeinbergerLake and Reservoir Management1040-23810743-8141211200524 - 29Influences of Lake Level Changes on Reservoir Water Clarity in Allatoona Lake, Georgia Authors: Joseph M. Dirnbergera; Jason Weinbergera Abstract In Allatoona Lake (Georgia USA), secchi transparency (measured every 2 to 4 weeks during a Phase I U.S. EPA Clean Lakes Study) was typically 5- to 8- fold greater in summer than late autumn and winter. The intensity of storms increased in late autumn and winter resulting in high sediment loads from the watershed, but lake level was also drawn down, confounding the influence of external sediment load with that of resuspended lake sediments. For 4 of the 5 years studied, decreases in water clarity were more closely synchronized with lowering of lake level than with storms. Continuous automated sampling of turbidity and other water quality parameters at 15-minute intervals allowed us to assess whether turbidity increases were derived from erosion of the exposed shoreline (i.e., by rain and runoff), or wave-driven resuspension. Regular increases in turbidity and decreases in pH occurred each weekend during the summer, suggesting increased mixing by boat traffic. Increases in turbidity on weekends and after rain events were greater after initiation of drawdown and were particularly strong when lake surface elevation approached that of the summer metalimnion depth. It appears that sediment focused (deposited) in deeper areas during the spring and summer is resuspended by wave action as lake levels drop in autumn. Keywords: water clarity; lake level; reservoir; sediment focusing; wind; turbidity View Full Text ArticleSubscribe Affiliation: a Department of Biological and Physical Sciences, Kennesaw State University, Kennesaw, GA DOI: 10.1080/07438140509354409 Published in: Lake and Reservoir Management Publication Frequency: 4 issues per year First Published on: 01 March 2005 Formats available: PDF (English) In Allatoona Lake (Georgia USA), secchi transparency (measured every 2 to 4 weeks during a Phase I U.S. EPA Clean Lakes Study) was typically 5- to 8- fold greater in summer than late autumn and winter. The intensity of storms increased in late autumn and winter resulting in high sediment loads from the watershed, but lake level was also drawn down, confounding the influence of external sediment load with that of resuspended lake sediments. For 4 of the 5 years studied, decreases in water clarity were more closely synchronized with lowering of lake level than with storms. Continuous automated sampling of turbidity and other water quality parameters at 15-minute intervals allowed us to assess whether turbidity increases were derived from erosion of the exposed shoreline (i.e., by rain and runoff), or wave-driven resuspension. Regular increases in turbidity and decreases in pH occurred each weekend during the summer, suggesting increased mixing by boat traffic. Increases in turbidity on weekends and after rain events were greater after initiation of drawdown and were particularly strong when lake surface elevation approached that of the summer metalimnion depth. It appears that sediment focused (deposited) in deeper areas during the spring and summer is resuspended by wave action as lake levels drop in autumn.
Evaluation of the Potential Adverse Effects of Lake Inflow Treatment with AlumKeith M. Pilgrim; Patrick L. BrezonikLake and Reservoir Management1040-23810743-8141211200577 - 87Evaluation of the Potential Adverse Effects of Lake Inflow Treatment with Alum Authors: Keith M. Pilgrima; Patrick L. Brezonika Abstract Laboratory and field investigations at Fish Lake in Eagan, MN, and Tanners Lake in Oakdale, MN, were conducted to evaluate the potential adverse effects of using alum to treat lake inflows. Detention ponds are used at both sites to promote settling of alum floc before discharge to the lake. Tests in a 1.5 m column designed to estimate settling in detention ponds showed nearly complete Al settling by 6 h. Final residual Al concentrations were affected only slightly by dose. Average concentrations of total Al entering Fish Lake were 346 and 458 μg Al L-1 at doses of 1 and 8 mg Al L-1, and average in-lake concentrations were 70 and 152 μg L-1. Aluminum settled in Fish Lake at a rate of 74 m y-1. Average Al concentrations in Tanners Lake inflow were higher, but Al concentrations in the lake were lower because of its greater size. The settling pond at Fish Lake protected benthic invertebrates in the lake, but floc accumulation during treatment at 8 mg Al L-1 eliminated nearly all invertebrates in the pond. Concentrations of Al that showed no observed mortality effects (NOECs) were assembled from literature, and a measure of unbound, positively charged Al species (Allm) was compared to the NOECs to evaluate potential aquatic toxicity from alum treatment. The potential risk of aquatic toxicity should be negligible if treated water entering the lake has a pH > 6.0. Keywords: alum treatment; aquatic toxicity; benthic invertebrates; aluminum; speciation View Full Text ArticleSubscribe Affiliation: a Water Resources Science Graduate Program and Department of Civil Engineering, University of Minnesota, Minneapolis, MN DOI: 10.1080/07438140509354408 Published in: Lake and Reservoir Management, Volume 21, Issue 1 March 2005 , pages 77 - 87 Publication Frequency: 4 issues per year First Published on: 01 March 2005 Formats available: PDF (English) Laboratory and field investigations at Fish Lake in Eagan, MN, and Tanners Lake in Oakdale, MN, were conducted to evaluate the potential adverse effects of using alum to treat lake inflows. Detention ponds are used at both sites to promote settling of alum floc before discharge to the lake. Tests in a 1.5 m column designed to estimate settling in detention ponds showed nearly complete Al settling by 6 h. Final residual Al concentrations were affected only slightly by dose. Average concentrations of total Al entering Fish Lake were 346 and 458 μg Al L-1 at doses of 1 and 8 mg Al L-1, and average in-lake concentrations were 70 and 152 μg L-1. Aluminum settled in Fish Lake at a rate of 74 m y-1. Average Al concentrations in Tanners Lake inflow were higher, but Al concentrations in the lake were lower because of its greater size. The settling pond at Fish Lake protected benthic invertebrates in the lake, but floc accumulation during treatment at 8 mg Al L-1 eliminated nearly all invertebrates in the pond. Concentrations of Al that showed no observed mortality effects (NOECs) were assembled from literature, and a measure of unbound, positively charged Al species (Allm) was compared to the NOECs to evaluate potential aquatic toxicity from alum treatment. The potential risk of aquatic toxicity should be negligible if treated water entering the lake has a pH > 6.0.
Treatment of Lake Inflows with Alum for Phosphorus RemovalKeith M. Pilgrim; Patrick L. BrezonikLake and Reservoir Management1040-23810743-814121120051-9Treatment of Lake Inflows with Alum for Phosphorus Removal Authors: Keith M. Pilgrimab; Patrick L. Brezonikac Abstract Alum is being used on an experimental basis to remove phosphorus (P) from the inflows of Fish and Tanners Lakes in the Minneapolis and St. Paul metropolitan area of Minnesota. Jar test studies and experiments with settling columns demonstrated the usefulness of these methods for proper design of inflow alum treatment systems. Mixing conditions in treatment facilities at both lakes promote good floc development. The degree of alum and water mixing, defined by the velocity gradient (G, s-1) and mixing time (t, in s), or Gt, was 7,700-35,000 for Tanners Lake and the maximum potential Gt for Fish Lake was 42,000. The concentration of TP entering Fish Lake was greatly reduced at an alum dose of 8 mg Al L-1 but was largely unaffected at 1 mg Al L-1. Average annual TP removal from 1998 to 2003 with alum doses of 1.9 to 10.5 mg Al L-1 ranged from 61 to 84% at Tanners Lake. Surface TP declined rapidly with alum treatment in both lakes. Average annual Secchi disk depth (SD) for the west bay of Fish Lake improved from 1.5 m in 1998 to 2.1 m in 2000 despite a 28 cm storm event in July 2000 that led to large inflows to the lake. Treatment at Tanners Lake, which occurred during the entire year, was effective in reducing the long-term (May through September) average TP concentration in the surface of Tanners Lake from approximately 50 to just under 30 μg L-1. Alum floc, which was deposited in sediments of a settling pond prior to Fish Lake and in the lake sediments inhibited P release under anoxic conditions. Keywords: alum treatment; phosphorus removal; design View Full Text ArticleSubscribe Affiliations: a Water Resources Science Program and Department of Civil Engineering, University of Minnesota, Minneapolis, MN b Barr Engineering, Minneapolis, MN c National Science Foundation, Arlington, VA DOI: 10.1080/07438140509354407 Published in: Lake and Reservoir Management, Volume 21, Issue 1 March 2005 , pages 1 - 9 Publication Frequency: 4 issues per year First Published on: 01 March 2005 Formats available: PDF (English) Alum is being used on an experimental basis to remove phosphorus (P) from the inflows of Fish and Tanners Lakes in the Minneapolis and St. Paul metropolitan area of Minnesota. Jar test studies and experiments with settling columns demonstrated the usefulness of these methods for proper design of inflow alum treatment systems. Mixing conditions in treatment facilities at both lakes promote good floc development. The degree of alum and water mixing, defined by the velocity gradient (G, s-1) and mixing time (t, in s), or Gt, was 7,700-35,000 for Tanners Lake and the maximum potential Gt for Fish Lake was 42,000. The concentration of TP entering Fish Lake was greatly reduced at an alum dose of 8 mg Al L-1 but was largely unaffected at 1 mg Al L-1. Average annual TP removal from 1998 to 2003 with alum doses of 1.9 to 10.5 mg Al L-1 ranged from 61 to 84% at Tanners Lake. Surface TP declined rapidly with alum treatment in both lakes. Average annual Secchi disk depth (SD) for the west bay of Fish Lake improved from 1.5 m in 1998 to 2.1 m in 2000 despite a 28 cm storm event in July 2000 that led to large inflows to the lake. Treatment at Tanners Lake, which occurred during the entire year, was effective in reducing the long-term (May through September) average TP concentration in the surface of Tanners Lake from approximately 50 to just under 30 μg L-1. Alum floc, which was deposited in sediments of a settling pond prior to Fish Lake and in the lake sediments inhibited P release under anoxic conditions.
VOC Loading from Marine Engines to a Multiple-use LakePrescott C. Heald; S. Geoffrey Schladow; Brant C. Allen; John E. ReuterLake and Reservoir Management1040-23810743-8141211200530 - 38VOC Loading from Marine Engines to a Multiple-use Lake Authors: Prescott C. Healda; S. Geoffrey Schladowb; Brant C. Allenc; John E. Reuterc Abstract A detailed boating use survey was conducted at a Northern California multiple-use lake, and the results were used to quantify daily MTBE and BTEX loading from recreational boating. Boat owner interviews and whole-lake activity surveys were conducted on 43 days between June 17 and September 20, 2000, including 38 days during the peak boating months of July and August. The dominant class of marine engines was found to be 4-stroke inboards and inboard/outboards, which constituted 60 percent of the total number of engines and consumed 69 percent of the fuel used at the lake. 2-stroke outboard engines with carburetors represented 26 percent of the engines and 14.3 percent of the fuel consumption, but were found to contribute 68 percent of MTBE and BTEX loading, while 4-stroke inboards were responsible for 4.2 percent. A sampling program was conducted in which MTBE/BTEX samples were collected on 23 days between May 22 and October 23, 2000. Results showed that MTBE appeared in 95 percent of epilimnetic samples up to a maximum concentration of 3.5 μg·l-1 while toluene was detected in 22 percent of epilimnetic samples at a maximum concentration of 0.5 μg·1-1. O-xylene was detected on one day, and benzene, ethlybenzene and m,p-xylene were not detected. The study demonstrated that MTBE is more persistent than BTEX compounds in surface water bodies, and accumulates over time with continuous inputs. Keywords: fuel; VOC; lake; MTBE; BTEX; loading View Full Text ArticleSubscribe Affiliations: a West Yost & Associates, Davis, CA b Department of Civil and Environmental Engineering, University of California, Davis, Davis, CA c Department of Environmental Science and Policy, University of California, Davis, Davis, CA DOI: 10.1080/07438140509354410 Published in: Lake and Reservoir Management, Volume 21, Issue 1 March 2005 , pages 30 - 38 Publication Frequency: 4 issues per year First Published on: 01 March 2005 Formats available: PDF (English) A detailed boating use survey was conducted at a Northern California multiple-use lake, and the results were used to quantify daily MTBE and BTEX loading from recreational boating. Boat owner interviews and whole-lake activity surveys were conducted on 43 days between June 17 and September 20, 2000, including 38 days during the peak boating months of July and August. The dominant class of marine engines was found to be 4-stroke inboards and inboard/outboards, which constituted 60 percent of the total number of engines and consumed 69 percent of the fuel used at the lake. 2-stroke outboard engines with carburetors represented 26 percent of the engines and 14.3 percent of the fuel consumption, but were found to contribute 68 percent of MTBE and BTEX loading, while 4-stroke inboards were responsible for 4.2 percent. A sampling program was conducted in which MTBE/BTEX samples were collected on 23 days between May 22 and October 23, 2000. Results showed that MTBE appeared in 95 percent of epilimnetic samples up to a maximum concentration of 3.5 μg·l-1 while toluene was detected in 22 percent of epilimnetic samples at a maximum concentration of 0.5 μg·1-1. O-xylene was detected on one day, and benzene, ethlybenzene and m,p-xylene were not detected. The study demonstrated that MTBE is more persistent than BTEX compounds in surface water bodies, and accumulates over time with continuous inputs.
Strategies for Managing the Lakes of the Rotorua District, New ZealandNoel Burns; John McIntosh; Paul ScholesLake and Reservoir Management1040-23810743-8141211200561 - 72Strategies for Managing the Lakes of the Rotorua District, New Zealand Authors: Noel Burnsa; John McIntoshb; Paul Scholesb Abstract The Rotorua district in New Zealand contains 12 nationally important lakes. Environment Bay of Plenty (EBOP), which has the responsibility of managing the quality of these lakes, set a routine monitoring program for these lakes and adopted the method of Burns et al. (1999, 2000) to analyse the data and calculate a numeric Trophic Level Index (TLI) value for each. In 1994, the district community indicated a goal to maintain the present condition for most of the lakes and to improve the remainder. As a result, numeric baseline TLI values were written into the Proposed Regional Water and Land Plan as the Rotorua District lake-water quality objectives. This plan also required formation of a community action plan for the remediation of any lake that exceeded its baseline TLI, a criterion that targeted five lakes. Deterioration in the water quality of these lakes is linked to urban expansion and gradual conversion of forested land to pasture over the past 100 years. Draft action plans identifying causes of lake deterioration, together with possible means of solving the problems, have been published for four lakes. Annual reports on the state of each lake have been published since 2000. This lake management system has resulted in valuable communication between EBOP, the Rotorua District Council and the communities living around the lakes, and has been instrumental in obtaining a cooperative approach to solving the identified problems. Methods to remediate these lakes include: converting pasture back to forest; alum dosing; creating riparian strips along streambanks; developing wetlands; installing reticulated sewage systems, and; diverting wastewater inputs from a lake into nearby forests. Keywords: lake monitoring; trophic levels; baseline trophic conditions; action plans; groundwater nitrate; water quality trends; global warming; New Zealand lakes View Full Text ArticleSubscribe Affiliations: a Lakes Consulting, Devonport, New Zealand b Environment Bay of Plenty, Whakatane, New Zealand DOI: 10.1080/07438140509354413 Published in: Lake and Reservoir Management, Volume 21, Issue 1 March 2005 , pages 61 - 72 Publication Frequency: 4 issues per year First Published on: 01 March 2005 Formats available: PDF (English) The Rotorua district in New Zealand contains 12 nationally important lakes. Environment Bay of Plenty (EBOP), which has the responsibility of managing the quality of these lakes, set a routine monitoring program for these lakes and adopted the method of Burns et al. (1999, 2000) to analyse the data and calculate a numeric Trophic Level Index (TLI) value for each. In 1994, the district community indicated a goal to maintain the present condition for most of the lakes and to improve the remainder. As a result, numeric baseline TLI values were written into the Proposed Regional Water and Land Plan as the Rotorua District lake-water quality objectives. This plan also required formation of a community action plan for the remediation of any lake that exceeded its baseline TLI, a criterion that targeted five lakes. Deterioration in the water quality of these lakes is linked to urban expansion and gradual conversion of forested land to pasture over the past 100 years. Draft action plans identifying causes of lake deterioration, together with possible means of solving the problems, have been published for four lakes. Annual reports on the state of each lake have been published since 2000. This lake management system has resulted in valuable communication between EBOP, the Rotorua District Council and the communities living around the lakes, and has been instrumental in obtaining a cooperative approach to solving the identified problems. Methods to remediate these lakes include: converting pasture back to forest; alum dosing; creating riparian strips along streambanks; developing wetlands; installing reticulated sewage systems, and; diverting wastewater inputs from a lake into nearby forests.
Changes in Primary Production in Onondaga Lake, NY: Magnitude, Metrics, and DriversSteven W. Effler; Rakesh K. Gelda; Stephen E. Field; Adam J. P. Effler; Erik B. Wallenberg; David A. MatthewsLake and Reservoir Management1040-23810743-8141211200549 - 60Changes in Primary Production in Onondaga Lake, NY: Magnitude, Metrics, and Drivers Authors: Steven W. Efflera; Rakesh K. Geldaa; Stephen E. Fielda; Adam J. P. Efflera; Erik B. Wallenberga; David A. Matthewsa Abstract Changes in phytoplankton primary production and common metrics and drivers of trophic state are documented and critically evaluated for a 35 year (1968-2002) period for polluted, culturally eutrophic Onondaga Lake, NY. The lake is presently the focus of an on-going rehabilitation program to abate its cultural eutrophication problems. The analysis is supported by measurements of primary production and long-term monitoring of trophic state metrics and other common limnological parameters. Measurements of primary production and community respiration were made in 1978, 2002, and portions of 2000 and 2001, utilizing dissolved oxygen-based isolated community (light/dark bottle) and non-isolated community (diel measurements) protocols. Limnological and discharge monitoring of the following metrics supported the analysis: epilimnetic total phosphorus, epilimnetic chlorophyll a (Chle), Secchi disc (SD), areal hypolimnetic oxygen deficit (AHOD), salinity (S), downward flux of particulate organic carbon (POCdf), and concentration of TP in the effluent of a wastewater treatment plant (TPMetro) that dominates loading. Direct measurements establish the areal daily average gross primary production has decreased ~ 30 to 40% since 1978. The magnitude of this decrease corresponds well with decreases observed in the surrogate metrics of primary production of POCdf (37%) and AHOD (49%). Detailed time series of POCdf and AHOD indicate the decrease occurred abruptly in the late 1980s. This decrease was primarily a result of the reduction in S that attended cessation of production by an industry, rather than a response to the 30-fold reduction in TPMetro achieved over the last 32 years. Magnitudes of Chle and SD are not presently reliable metrics of trophic state in this lake because of increases, and year-to-year variations, in top-down effects since closure of the industry. Keywords: primary production; trophic state; water quality; Onondaga Lake; eutrophication; dissolved oxygen; metabolic rates; light-dark bottles View Full Text ArticleSubscribe Affiliation: a Upstate Freshwater Institute, Syracuse, NY DOI: 10.1080/07438140509354412 Published in: Lake and Reservoir Management, Volume 21, Issue 1 March 2005 , pages 49 - 60 Publication Frequency: 4 issues per year First Published on: 01 March 2005 Formats available: PDF (English) Changes in phytoplankton primary production and common metrics and drivers of trophic state are documented and critically evaluated for a 35 year (1968-2002) period for polluted, culturally eutrophic Onondaga Lake, NY. The lake is presently the focus of an on-going rehabilitation program to abate its cultural eutrophication problems. The analysis is supported by measurements of primary production and long-term monitoring of trophic state metrics and other common limnological parameters. Measurements of primary production and community respiration were made in 1978, 2002, and portions of 2000 and 2001, utilizing dissolved oxygen-based isolated community (light/dark bottle) and non-isolated community (diel measurements) protocols. Limnological and discharge monitoring of the following metrics supported the analysis: epilimnetic total phosphorus, epilimnetic chlorophyll a (Chle), Secchi disc (SD), areal hypolimnetic oxygen deficit (AHOD), salinity (S), downward flux of particulate organic carbon (POCdf), and concentration of TP in the effluent of a wastewater treatment plant (TPMetro) that dominates loading. Direct measurements establish the areal daily average gross primary production has decreased ~ 30 to 40% since 1978. The magnitude of this decrease corresponds well with decreases observed in the surrogate metrics of primary production of POCdf (37%) and AHOD (49%). Detailed time series of POCdf and AHOD indicate the decrease occurred abruptly in the late 1980s. This decrease was primarily a result of the reduction in S that attended cessation of production by an industry, rather than a response to the 30-fold reduction in TPMetro achieved over the last 32 years. Magnitudes of Chle and SD are not presently reliable metrics of trophic state in this lake because of increases, and year-to-year variations, in top-down effects since closure of the industry.
Temporal Coherence in Limnological Features of Two Southwestern ReservoirsThomas H. Chrzanowski; James P. GroverLake and Reservoir Management1040-23810743-8141211200539 - 48Temporal Coherence in Limnological Features of Two Southwestern Reservoirs Authors: Thomas H. Chrzanowskia; James P. Grovera Abstract Properties of aquatic ecosystems have recently been considered in a landscape context where lakes in a geographic area are examined to identify common and long-term behavior patterns for one or more variables. Identifying such temporally coherent features should permit generalizations about lake behavior in specific regions and therefore, predictive models based upon such information should have broad applicability within a regional landscape. We considered the temporal coherence of a number of physical, chemical, and biological features of two southwestern reservoirs that differed in age, watersheds, and trophic status to identify common landscape-level predictors of behavior. We found synchronous behavior (temporal coherence) associated with particulate nutrient dynamics (organic carbon, nitrogen and phosphate (PP)), dissolved factors that force plankton dynamics (total dissolved phosphate, reactive phosphate and reactive silicate (SRSi), and with nutrient ratios used as indices of nutrient limitation in the plankton (TDN:TDP, C:P, and N:P). Algal parameters related to biomass (chlorophyll and Simpson's diversity index) did not vary coherently but algal genus richness and bacterial abundance did. Temperature was identified as a forcing function explaining synchronous variability in all cases except SRSi, PP, C:P, N:P, bacteria, and richness. The two systems, although managed for different purposes, behaved similarly with respect to several commonly measured limnological features, most notably, those involving phosphorus. We conclude that it may be possible to use such analysis to establish reference conditions for reservoirs in a given geographic region. Keywords: reservoirs; synchrony; nutrients; models View Full Text ArticleSubscribe Affiliation: a Department of Biology, The University of Texas at Arlington, Arlington, TX DOI: 10.1080/07438140509354411 Published in: Lake and Reservoir Management, Volume 21, Issue 1 March 2005 , pages 39 - 48 Publication Frequency: 4 issues per year First Published on: 01 March 2005 Formats available: PDF (English) Properties of aquatic ecosystems have recently been considered in a landscape context where lakes in a geographic area are examined to identify common and long-term behavior patterns for one or more variables. Identifying such temporally coherent features should permit generalizations about lake behavior in specific regions and therefore, predictive models based upon such information should have broad applicability within a regional landscape. We considered the temporal coherence of a number of physical, chemical, and biological features of two southwestern reservoirs that differed in age, watersheds, and trophic status to identify common landscape-level predictors of behavior. We found synchronous behavior (temporal coherence) associated with particulate nutrient dynamics (organic carbon, nitrogen and phosphate (PP)), dissolved factors that force plankton dynamics (total dissolved phosphate, reactive phosphate and reactive silicate (SRSi), and with nutrient ratios used as indices of nutrient limitation in the plankton (TDN:TDP, C:P, and N:P). Algal parameters related to biomass (chlorophyll and Simpson's diversity index) did not vary coherently but algal genus richness and bacterial abundance did. Temperature was identified as a forcing function explaining synchronous variability in all cases except SRSi, PP, C:P, N:P, bacteria, and richness. The two systems, although managed for different purposes, behaved similarly with respect to several commonly measured limnological features, most notably, those involving phosphorus. We conclude that it may be possible to use such analysis to establish reference conditions for reservoirs in a given geographic region.
Simple Graphical Methods for the Interpretation of Relationships Between Trophic State VariablesRobert E. Carlson; Karl E. HavensLake and Reservoir Management1040-23810743-81412112005107 - 118Simple Graphical Methods for the Interpretation of Relationships Between Trophic State Variables Authors: Robert E. Carlsona; Karl E. Havensb Abstract Graphical methods are presented that can identify relationships between the trophic state variables, total phosphorus, total nitrogen, chlorophyll, and Secchi depth. The graphical approach extends the use of empirical models beyond predictions based solely on local data. Instead, the authors suggest comparing the data against an established set of predictive equations. These equations serve as a “standard model” from which deviations can be observed and inter-preted. The goal of the use of deviations from a standard model is to enhance our ability to understand relationships between important nutrient, transparency, and biological variables and to adjust our predictive models and manage-ment decisions accordingly. Examples are given of interpretations of deviations caused by nitrogen limitation, non-algal turbidity, zooplankton grazing, and dissolved water color. Keywords: trophic state; empirical models; lakes; TSI; phosphorus; chlorophyll; Secchi depth; nutrient limitation View Full Text ArticleSubscribe Affiliations: a Department of Biological Sciences, Kent State University, Kent, OH b South Florida Water Management District, West Palm Beach, FL DOI: 10.1080/07438140509354418 Published in: Lake and Reservoir Management, Volume 21, Issue 1 March 2005 , pages 107 - 118 Publication Frequency: 4 issues per year First Published on: 01 March 2005 Formats available: PDF (English) Graphical methods are presented that can identify relationships between the trophic state variables, total phosphorus, total nitrogen, chlorophyll, and Secchi depth. The graphical approach extends the use of empirical models beyond predictions based solely on local data. Instead, the authors suggest comparing the data against an established set of predictive equations. These equations serve as a “standard model” from which deviations can be observed and inter-preted. The goal of the use of deviations from a standard model is to enhance our ability to understand relationships between important nutrient, transparency, and biological variables and to adjust our predictive models and manage-ment decisions accordingly. Examples are given of interpretations of deviations caused by nitrogen limitation, non-algal turbidity, zooplankton grazing, and dissolved water color.
Changes in Water Quality in an Urban Stream Following the Use of Organically Derived Deicing ProductsMatthew AlbrightLake and Reservoir Management1040-23810743-81412112005119 - 124Changes in Water Quality in an Urban Stream Following the Use of Organically Derived Deicing Products Author: Matthew Albrighta Abstract Willow Brook receives runoff from Cooperstown, NY and flows into Otsego Lake, a phosphorus limited, mesotrophic waterbody. Between 1992 and 1998, the Village of Cooperstown's winter road management policy included plowing and applying abrasives (particulate material intended to increase traction) mixed with enough salt to minimize clumping. Between 1998 and 2002, Ice Ban Magicâ„¢ and Magic Minus Zeroâ„¢, both organic deicers mixed with magnesium chloride, were applied experimentally in conjunction with abrasives and salt. During the winter of 2002/2003, road treatment consisted solely of applications of salt which had been treated with Magic Minus Zeroâ„¢. Precipitation-based monitoring on Willow Brook conducted between 1991 and 2003 revealed significant declines in the export of total phosphorus, despite elevated phosphorus levels in Ice Ban Magicâ„¢ and Magic Minus Zeroâ„¢, and suspended sediment as the volume of abrasives applied to roads was reduced. Chloride levels are increasing, however. The implicit trade-offs between potential pollutants and the cost of road management in cold climates are acknowledged for management of transportation safety. Keywords: phosphorus; suspended sediment; chloride; winter road management; abrasives; Ice Ban View Full Text ArticleSubscribe Affiliation: a State University of New York College at Oneonta Biological Field Station, Cooperstown, NY DOI: 10.1080/07438140509354419 Published in: Lake and Reservoir Management, Volume 21, Issue 1 March 2005 , pages 119 - 124 Publication Frequency: 4 issues per year First Published on: 01 March 2005 Formats available: PDF (English) Willow Brook receives runoff from Cooperstown, NY and flows into Otsego Lake, a phosphorus limited, mesotrophic waterbody. Between 1992 and 1998, the Village of Cooperstown's winter road management policy included plowing and applying abrasives (particulate material intended to increase traction) mixed with enough salt to minimize clumping. Between 1998 and 2002, Ice Ban Magicâ„¢ and Magic Minus Zeroâ„¢, both organic deicers mixed with magnesium chloride, were applied experimentally in conjunction with abrasives and salt. During the winter of 2002/2003, road treatment consisted solely of applications of salt which had been treated with Magic Minus Zeroâ„¢. Precipitation-based monitoring on Willow Brook conducted between 1991 and 2003 revealed significant declines in the export of total phosphorus, despite elevated phosphorus levels in Ice Ban Magicâ„¢ and Magic Minus Zeroâ„¢, and suspended sediment as the volume of abrasives applied to roads was reduced. Chloride levels are increasing, however. The implicit trade-offs between potential pollutants and the cost of road management in cold climates are acknowledged for management of transportation safety.
Shoreline DensityRichard A. OsgoodLake and Reservoir Management1040-23810743-81412112005125 - 126Shoreline Density Author: Richard A. Osgooda Abstract A new morphometric index, shoreline density, is presented. Shoreline density, the length of shoreline divided by surface area, is useful for evaluating or comparing shoreline-associated impacts. Keywords: Shoreline development index; shoreline development; shoreline impacts View Full Text ArticleSubscribe Affiliation: a Osgood Consulting, Shorewood, MN DOI: 10.1080/07438140509354420 Published in: Lake and Reservoir Management, Volume 21, Issue 1 March 2005 , pages 125 - 126 Publication Frequency: 4 issues per year First Published on: 01 March 2005 Formats available: PDF (English) A new morphometric index, shoreline density, is presented. Shoreline density, the length of shoreline divided by surface area, is useful for evaluating or comparing shoreline-associated impacts.
Long-term Changes in Iron and Phosphorus Sedimentation in Vadnais Lake, Minnesota, Resulting from Ferric Chloride Addition and Hypolimnetic AerationDaniel R. EngstromLake and Reservoir Management1040-23810743-8141211200595 - 105Long-term Changes in Iron and Phosphorus Sedimentation in Vadnais Lake, Minnesota, Resulting from Ferric Chloride Addition and Hypolimnetic Aeration Author: Daniel R. Engstroma Abstract Changes in iron (Fe) and phosphorus (P) cycling in Vadnais Lake, Minnesota, resulting from ferric chloride addition and hypolimnetic aeration are evaluated by repeat sampling of bottom sediments over a 13-year period: in 1985 (pre-treatment), and in 1990 and 1998 (post-treatment). Lead-210 derived accumulation rates for Fe, Mn, total-P, and P-fractions are combined with input/output monitoring to construct chemical mass-balances for each of the three time periods. Iron injections/aeration caused large and sustained reductions in water-column total-P by increasing phosphorus removal to the sediments and preventing its recycling during stratification. Annual whole-lake phosphorus sedimentation rose from 1.26 to 1.52 t between 1985 and 1990, equivalent to a doubling of in-lake retention of external P loads (from 19% to 38%). Most of the increase is represented in the labile Fe-bound fraction. The measured sedimentary fluxes for 1985 and 1990 are similar to those calculated by difference from inflow/outflow data, whereas measured P sedimentation in 1998 (2.43 t·yr-1) is three times higher than that estimated from input/output calculations. These results suggest surface enrichment by upward P diffusion within the sediment column. Present-day Fe accumulation rates (24 t·yr-1) are 33% greater than those immediately preceding treatment and 14% greater than pre-settlement fluxes (21 t·yr-1). The 6 t·yr-1 increase in Fe accumulation between 1985 and 1998 is roughly equal to the rate of iron injection to Vadnais Lake. Fifty-four tons of iron addition to the Lambert Creek tributary between 1990 and 1998 have also enriched littoral sediments in Fe, P, and Mn near the creek's outfall. These engineering solutions have substantially improved water quality in Vadnais Lake, but continued hypolimnetic aeration will be required to prevent internal phosphorus loading from the large reservoir of labile sedimentary P that has accumulated since treatment began. Keywords: Iron addition; hypolimnetic aeration; sedimentation; phosphorus inactivation; internal loading View Full Text ArticleSubscribe Affiliation: a St. Croix Watershed Research Station Science Museum of Minnesota, Marine on St. Croix, MN DOI: 10.1080/07438140509354417 Published in: Lake and Reservoir Management, Volume 21, Issue 1 March 2005 , pages 95 - 105 Publication Frequency: 4 issues per year First Published on: 01 March 2005 Formats available: PDF (English) Changes in iron (Fe) and phosphorus (P) cycling in Vadnais Lake, Minnesota, resulting from ferric chloride addition and hypolimnetic aeration are evaluated by repeat sampling of bottom sediments over a 13-year period: in 1985 (pre-treatment), and in 1990 and 1998 (post-treatment). Lead-210 derived accumulation rates for Fe, Mn, total-P, and P-fractions are combined with input/output monitoring to construct chemical mass-balances for each of the three time periods. Iron injections/aeration caused large and sustained reductions in water-column total-P by increasing phosphorus removal to the sediments and preventing its recycling during stratification. Annual whole-lake phosphorus sedimentation rose from 1.26 to 1.52 t between 1985 and 1990, equivalent to a doubling of in-lake retention of external P loads (from 19% to 38%). Most of the increase is represented in the labile Fe-bound fraction. The measured sedimentary fluxes for 1985 and 1990 are similar to those calculated by difference from inflow/outflow data, whereas measured P sedimentation in 1998 (2.43 t·yr-1) is three times higher than that estimated from input/output calculations. These results suggest surface enrichment by upward P diffusion within the sediment column. Present-day Fe accumulation rates (24 t·yr-1) are 33% greater than those immediately preceding treatment and 14% greater than pre-settlement fluxes (21 t·yr-1). The 6 t·yr-1 increase in Fe accumulation between 1985 and 1998 is roughly equal to the rate of iron injection to Vadnais Lake. Fifty-four tons of iron addition to the Lambert Creek tributary between 1990 and 1998 have also enriched littoral sediments in Fe, P, and Mn near the creek's outfall. These engineering solutions have substantially improved water quality in Vadnais Lake, but continued hypolimnetic aeration will be required to prevent internal phosphorus loading from the large reservoir of labile sedimentary P that has accumulated since treatment began.
Use of IDEXX Colilert-18® and Quanti-Tray/2000 as a Rapid and Simple Enumeration Method for the Implementation of Recreational Water Monitoring and Notification ProgramsJulie L. Kinzelman; Ajaib Singh; Clem Ng; Kathy R. Pond; Robert C. Bagley; Stephen GradusLake and Reservoir Management1040-23810743-8141211200573 - 77Use of IDEXX Colilert-18® and Quanti-Tray/2000 as a Rapid and Simple Enumeration Method for the Implementation of Recreational Water Monitoring and Notification Programs Authors: Julie L. Kinzelmanab; Ajaib Singhc; Clem Ngc; Kathy R. Pondb; Robert C. Bagleya; Stephen Gradusc Abstract The Beaches Environmental Assessment and Coastal Health Act of 2002 (BEACH Act) requires the implementation and/or expansion of routine recreational water quality monitoring programs in all United States coastal recreational waters, including the Great Lakes, to be adopted by 2004. While the standardization of sample collection and laboratory testing protocols is essential, the ability to provide timely public notification is an equally important element. In preparation for the implementation of the BEACH Act in Wisconsin the communities of Milwaukee and Racine investigated the use of IDEXX Colilert-18, Quanti-Tray/2000 (IDEXX) as a means to reduce the time necessary for public notification of recreational water quality while still providing accurate and consistent test results. Conducted over a 2-year period, this study compared two methods, IDEXX and an approved USEPA membrane filtration method (m-Tec agar), for the quantitative determination of Escherichia coli in split samples from fresh water beaches. ANOVA analysis of regression relation indicated no significant difference between the data sets obtained using these methodologies (p < 0.001). Parallel studies conducted in the United Kingdom produced similar results. The fact that IDEXX decreases the time from sample collection to public notification by over six hours coupled with its ease of use and consistent results make this method an attractive choice for the implementation of fresh water and marine beach management programs. Keywords: E. coli; BEACH Act of 2000; recreational water quality monitoring View Full Text ArticleSubscribe Affiliations: a City of Racine Health Department Laboratory, Racine, WI b Robens Centre for Public and Environmental Health, Univ. of Surrey, Guildford, Surrey, UK c City of Milwaukee Health Department Laboratory, Milwaukee, WI DOI: 10.1080/07438140509354414 Published in: Lake and Reservoir Management, Volume 21, Issue 1 March 2005 , pages 73 - 77 Publication Frequency: 4 issues per year First Published on: 01 March 2005 Formats available: PDF (English) The Beaches Environmental Assessment and Coastal Health Act of 2002 (BEACH Act) requires the implementation and/or expansion of routine recreational water quality monitoring programs in all United States coastal recreational waters, including the Great Lakes, to be adopted by 2004. While the standardization of sample collection and laboratory testing protocols is essential, the ability to provide timely public notification is an equally important element. In preparation for the implementation of the BEACH Act in Wisconsin the communities of Milwaukee and Racine investigated the use of IDEXX Colilert-18, Quanti-Tray/2000 (IDEXX) as a means to reduce the time necessary for public notification of recreational water quality while still providing accurate and consistent test results. Conducted over a 2-year period, this study compared two methods, IDEXX and an approved USEPA membrane filtration method (m-Tec agar), for the quantitative determination of Escherichia coli in split samples from fresh water beaches. ANOVA analysis of regression relation indicated no significant difference between the data sets obtained using these methodologies (p < 0.001). Parallel studies conducted in the United Kingdom produced similar results. The fact that IDEXX decreases the time from sample collection to public notification by over six hours coupled with its ease of use and consistent results make this method an attractive choice for the implementation of fresh water and marine beach management programs.
Evaluation of the Potential Adverse Effects of Lake Inflow Treatment with AlumKeith M. Pilgrim; Patrick L. BrezonikLake and Reservoir Management1040-23810743-8141211200577 - 87Evaluation of the Potential Adverse Effects of Lake Inflow Treatment with Alum Authors: Keith M. Pilgrimab; Patrick L. Brezonikac Abstract Laboratory and field investigations at Fish Lake in Eagan, MN, and Tanners Lake in Oakdale, MN, were conducted to evaluate the potential adverse effects of using alum to treat lake inflows. Detention ponds are used at both sites to promote settling of alum floc before discharge to the lake. Tests in a 1.5 m column designed to estimate settling in detention ponds showed nearly complete Al settling by 6 h. Final residual Al concentrations were affected only slightly by dose. Average concentrations of total Al entering Fish Lake were 346 and 458 μg Al L-1 at doses of 1 and 8 mg Al L-1, and average in-lake concentrations were 70 and 152 μg L-1. Aluminum settled in Fish Lake at a rate of 74 m y-1. Average Al concentrations in Tanners Lake inflow were higher, but Al concentrations in the lake were lower because of its greater size. The settling pond at Fish Lake protected benthic invertebrates in the lake, but floc accumulation during treatment at 8 mg Al L-1 eliminated nearly all invertebrates in the pond. Concentrations of Al that showed no observed mortality effects (NOECs) were assembled from literature, and a measure of unbound, positively charged Al species (Allm) was compared to the NOECs to evaluate potential aquatic toxicity from alum treatment. The potential risk of aquatic toxicity should be negligible if treated water entering the lake has a pH > 6.0. Keywords: alum treatment; aquatic toxicity; benthic invertebrates; aluminum; speciation View Full Text ArticleSubscribe Affiliations: a Water Resources Science Graduate Program and Department of Civil Engineering, University of Minnesota, Minneapolis, MN b Barr Engineering, Minneapolis, MN c National Science Foundation, Arlington, VA DOI: 10.1080/07438140509354415 Published in: Lake and Reservoir Management, Volume 21, Issue 1 March 2005 , pages 77 - 87 Publication Frequency: 4 issues per year First Published on: 01 March 2005 Formats available: PDF (English) Laboratory and field investigations at Fish Lake in Eagan, MN, and Tanners Lake in Oakdale, MN, were conducted to evaluate the potential adverse effects of using alum to treat lake inflows. Detention ponds are used at both sites to promote settling of alum floc before discharge to the lake. Tests in a 1.5 m column designed to estimate settling in detention ponds showed nearly complete Al settling by 6 h. Final residual Al concentrations were affected only slightly by dose. Average concentrations of total Al entering Fish Lake were 346 and 458 μg Al L-1 at doses of 1 and 8 mg Al L-1, and average in-lake concentrations were 70 and 152 μg L-1. Aluminum settled in Fish Lake at a rate of 74 m y-1. Average Al concentrations in Tanners Lake inflow were higher, but Al concentrations in the lake were lower because of its greater size. The settling pond at Fish Lake protected benthic invertebrates in the lake, but floc accumulation during treatment at 8 mg Al L-1 eliminated nearly all invertebrates in the pond. Concentrations of Al that showed no observed mortality effects (NOECs) were assembled from literature, and a measure of unbound, positively charged Al species (Allm) was compared to the NOECs to evaluate potential aquatic toxicity from alum treatment. The potential risk of aquatic toxicity should be negligible if treated water entering the lake has a pH > 6.0.
Relationship Between Largemouth Bass Recruitment and Water Level Dynamics in a Puerto Rico ReservoirOzcan Ozen; Richard L. NobleLake and Reservoir Management1040-23810743-8141211200589 - 95Relationship Between Largemouth Bass Recruitment and Water Level Dynamics in a Puerto Rico Reservoir Authors: Ozcan Ozenab; Richard L. Noblea Abstract Recruitment of largemouth bass at age-1 in a Puerto Rico reservoir can be predicted from water level variables of the previous year. Age-1 largemouth bass electrofishing catch-per-unit-effort (CPUE) as an index of year-class strength varied five fold between 1994 and 2001 in Lucchetti Reservoir, Puerto Rico. The CPUE of age-1 largemouth bass was higher in years when the water level of the previous years (1993-2000) remained high during the spawning period (January-June). The greatest water level drop (11.2 m) during the spawning period was observed in 1999, resulting in a water volume decrease of 66.5%, which corresponded to the lowest recruitment (CPUE 24.2 fish·h-1). With only 2.6 m of water level drop and 18.3% water volume decrease during the spawning period, the 1995 largemouth bass cohort was the strongest (CPUE 128.3 fish·h-1). The effect of these hydrological variables on largemouth bass recruitment appeared to be exponential rather than linear. Age-1 largemouth bass comprise the majority of the fishable stock in Lucchetti Reservoir, and the stock is typically below carrying capacity. Thus, the potential exists to adopt a water level management plan during the spawning period of largemouth bass to ensure successful largemouth bass recruitment into the next year's fishable stock. Keywords: tropical reservoir; hydrology; water level; largemouth bass; recruitment View Full Text ArticleSubscribe Affiliations: a Department of Zoology, North Carolina State University, Raleigh, NC, USA b Canakkale Onsekiz Mart Universitesi, Su Urunleri Fakultesi, Canakkale, TURKEY DOI: 10.1080/07438140509354416 Published in: Lake and Reservoir Management, Volume 21, Issue 1 March 2005 , pages 89 - 95 Publication Frequency: 4 issues per year First Published on: 01 March 2005 Formats available: PDF (English) Recruitment of largemouth bass at age-1 in a Puerto Rico reservoir can be predicted from water level variables of the previous year. Age-1 largemouth bass electrofishing catch-per-unit-effort (CPUE) as an index of year-class strength varied five fold between 1994 and 2001 in Lucchetti Reservoir, Puerto Rico. The CPUE of age-1 largemouth bass was higher in years when the water level of the previous years (1993-2000) remained high during the spawning period (January-June). The greatest water level drop (11.2 m) during the spawning period was observed in 1999, resulting in a water volume decrease of 66.5%, which corresponded to the lowest recruitment (CPUE 24.2 fish·h-1). With only 2.6 m of water level drop and 18.3% water volume decrease during the spawning period, the 1995 largemouth bass cohort was the strongest (CPUE 128.3 fish·h-1). The effect of these hydrological variables on largemouth bass recruitment appeared to be exponential rather than linear. Age-1 largemouth bass comprise the majority of the fishable stock in Lucchetti Reservoir, and the stock is typically below carrying capacity. Thus, the potential exists to adopt a water level management plan during the spawning period of largemouth bass to ensure successful largemouth bass recruitment into the next year's fishable stock.
Temperature Stratification and Mixing Dynamics in a Shallow Lake With Submersed MacrophytesWilliam R. Herb; Heinz G. StefanLake and Reservoir Management1040-23810743-81412042004 296 - 308Temperature Stratification and Mixing Dynamics in a Shallow Lake With Submersed Macrophytes Authors: William R. Herba; Heinz G. Stefana Abstract This paper describes an investigation of temperature stratification and vertical mixing in lacustrine macrophyte beds. Field measurements in a shallow lake show pronounced diel temperature dynamics, driven by surface heat transfer. The temperature stratification data also indicate a significant dependence of vertical mixing characteristics on macrophyte stand height. While natural convective mixing during night-time cooling was rather uniform between measurement sites, wind-driven mixing during the day was significantly attenuated in dense, full-depth macrophyte beds, resulting in increased stratification and higher maximum surface temperatures. An unsteady, one-dimensional heat transfer model has been formulated to simulate temperature dynamics in shallow lakes with submersed macrophytes. Surface mixed layer dynamics are successfully modeled at time scales down to 1 hour, using an integral energy model formulated to include the effect of light attenuation and turbulent kineuc energy dissipation by submersed macrophytes. The results of this study have implications for the management of water quality and ecology of shallow lakes, as variation of thermal stratification and mixing likely has corresponding effects on the transport of dissolved oxygen and nutrients. Keywords: heat transfer model; shallow lake; stratification; submersed macrophytes; water temperature; wind mixing View Full Text ArticleSubscribe Affiliation: a St. Anthony Falls Laboratory, University of Minnesota, Minneapolis, MN, USA DOI: 10.1080/07438140409354159 Published in: Lake and Reservoir Management Publication Frequency: 4 issues per year First Published on: 01 December 2004 Formats available: PDF (English) This paper describes an investigation of temperature stratification and vertical mixing in lacustrine macrophyte beds. Field measurements in a shallow lake show pronounced diel temperature dynamics, driven by surface heat transfer. The temperature stratification data also indicate a significant dependence of vertical mixing characteristics on macrophyte stand height. While natural convective mixing during night-time cooling was rather uniform between measurement sites, wind-driven mixing during the day was significantly attenuated in dense, full-depth macrophyte beds, resulting in increased stratification and higher maximum surface temperatures. An unsteady, one-dimensional heat transfer model has been formulated to simulate temperature dynamics in shallow lakes with submersed macrophytes. Surface mixed layer dynamics are successfully modeled at time scales down to 1 hour, using an integral energy model formulated to include the effect of light attenuation and turbulent kineuc energy dissipation by submersed macrophytes. The results of this study have implications for the management of water quality and ecology of shallow lakes, as variation of thermal stratification and mixing likely has corresponding effects on the transport of dissolved oxygen and nutrients.
Water Level Drawdown Affects Physical and Biogeochemical Properties of Littoral Sediments of a Reservoir and a Natural LakeP. C. Furey; R. N. Nordin; A. MazumderLake and Reservoir Management1040-23810743-81412042004 280 - 295Water Level Drawdown Affects Physical and Biogeochemical Properties of Littoral Sediments of a Reservoir and a Natural Lake Authors: P. C. Fureya; R. N. Nordinb; A. Mazumderb Abstract To determine the influence of water level drawdown on littoral areas, we compared the temporal and spatial changes in the water column and sediment in the littoral region of a drinking water reservoir and a natural lake. The reservoir (Sooke) experiences more than six meters of seasonal drawdown compared to a nearby, morphometrically and trophically similar lake (Shawnigan) that experiences less than one meter of drawdown. A greater drawdown in Sooke increased the littoral area and resulted in more littoral water column mixing, more solar warming, and higher PAR at a greater range of littoral depths than in Shawnigan. Based on sediment physical and chemical characteristics, sites farthest from shore were most similar, whereas sites in the drawdown exposure zone of Sooke and the upper littoral area of Shawnigan showed the largest differences. Low macrophyte abundance and loss of fine sediments, nutrients, and organic matter from the drawdown exposure zone in Sooke compared to the equivalent littoral area in Shawnigan suggest that drawdown enhances sediment erosion and focusing. Element and stable isotope ratios of sediment carbon and nitrogen suggest organic matter in the drawdown zone in Sooke is more allochthonous in origin and is coupled more strongly with deeper sites than in Shawnigan. Organic matter source and distribution also suggests that the littoral area extends out farther in Sooke than Shawnigan. This study demonstrates that drawdown has the potential to fundamentally change reservoir littoral sediment and biogeochemical characteristics. Understanding how littoral zones in reservoirs respond to drawdown compared to natural lakes may help water managers make more ecologically informed decisions regarding drawdown impacts on the ecology of littoral zones and water quality. Keywords: drinking water reservoir; littoral; sediment; macrophyte; nutrient; organic matter; biogeochemistry; stable isotope View Full Text ArticleSubscribe Affiliations: a Department of Biological Sciences, Bowling Green State University, Bowling Green, Ohio, USA b Water and Watershed Ecology Program Department of Biology, University of Victoria, Victoria, British Columbia, Canada DOI: 10.1080/07438140409354158 Published in: Lake and Reservoir Management, Volume 20, Issue 4 December 2004 , pages 280 - 295 Publication Frequency: 4 issues per year First Published on: 01 December 2004 Formats available: PDF (English) To determine the influence of water level drawdown on littoral areas, we compared the temporal and spatial changes in the water column and sediment in the littoral region of a drinking water reservoir and a natural lake. The reservoir (Sooke) experiences more than six meters of seasonal drawdown compared to a nearby, morphometrically and trophically similar lake (Shawnigan) that experiences less than one meter of drawdown. A greater drawdown in Sooke increased the littoral area and resulted in more littoral water column mixing, more solar warming, and higher PAR at a greater range of littoral depths than in Shawnigan. Based on sediment physical and chemical characteristics, sites farthest from shore were most similar, whereas sites in the drawdown exposure zone of Sooke and the upper littoral area of Shawnigan showed the largest differences. Low macrophyte abundance and loss of fine sediments, nutrients, and organic matter from the drawdown exposure zone in Sooke compared to the equivalent littoral area in Shawnigan suggest that drawdown enhances sediment erosion and focusing. Element and stable isotope ratios of sediment carbon and nitrogen suggest organic matter in the drawdown zone in Sooke is more allochthonous in origin and is coupled more strongly with deeper sites than in Shawnigan. Organic matter source and distribution also suggests that the littoral area extends out farther in Sooke than Shawnigan. This study demonstrates that drawdown has the potential to fundamentally change reservoir littoral sediment and biogeochemical characteristics. Understanding how littoral zones in reservoirs respond to drawdown compared to natural lakes may help water managers make more ecologically informed decisions regarding drawdown impacts on the ecology of littoral zones and water quality.
Impacts of Metal Salt Addition on Water Chemistry of Lake Elsinore, California: 2. Calcium SaltsMichael A. AndersonLake and Reservoir Management1040-23810743-81412042004 270 - 279Impacts of Metal Salt Addition on Water Chemistry of Lake Elsinore, California: 2. Calcium Salts Author: Michael A. Andersona Abstract Laboratory studies using water samples collected from Lake Elsinore in June 2002 demonstrated that addition of CA2+ substantively changed the water chemistry. The addition of agricultural gypsum, rock gypsum and CaCl2 all lowered equilibrium pH and alkalinity levels, while increasing the dissolved Ca2+ concentration. Solution pH decreased linearly with increasing Ca2+ dose, from 9.0 with no added Ca2+, to about 8.4 at a dose of 200 mg·L-1. Alkalinity decreased from 10.5 to about 3.5 meq·L-1, while dissolved Ca2+ levels increased from 20.6 to approximately 100 mg·L-1 over this same dose range. Addition of CaO and Ca(OH)2 had a comparatively small effect on equilibrium chemistry and maintained high pH, high alkalinity and low Ca2+ levels in the water. The kinetics of these changes were quite slow; equilibrium was generally reached between 4-7 days depending upon Ca-salt used and the rate of mixing. The Ca-salt additions resulted in modest (30-40%) reductions in total phosphorus (TP) and chlorophyll levels. Sorption and core-flux experiments demonstrated limited capacity of precipitated CaCO3 to sorb soluble-reactive phosphorus (SRP). More substantial removal was achieved, however, via coprecipitation of SRP with CaCO3 formed in situ from Ca2+-amended recycled water added to Lake Elsinore water, although removal efficiencies remained well below those typically achieved with alum. Based upon these findings, some general recommendations can be made about Ca2+ addition to lakes for the control of phosphorus: (i) Ca2+ addition to lakes will be more effective during periods of high SRP concentrations; (ii) addition of Ca-salts that promote coprecipitation of SRP with CaCO3 formed in situ is more effective at removing SRP from the water column than adsorption to preformed CaCO3; and (iii) the form and dose of the Ca-salt dramatically influences the final chemical condition of the water. Keywords: calcium; chemistry; Lake Elsinore View Full Text ArticleSubscribe Affiliation: a Department of Environmental Sciences, University of California, Riverside, CA DOI: 10.1080/07438140409354157 Published in: Lake and Reservoir Management, Volume 20, Issue 4 December 2004 , pages 270 - 279 Publication Frequency: 4 issues per year First Published on: 01 December 2004 Formats available: PDF (English) Laboratory studies using water samples collected from Lake Elsinore in June 2002 demonstrated that addition of CA2+ substantively changed the water chemistry. The addition of agricultural gypsum, rock gypsum and CaCl2 all lowered equilibrium pH and alkalinity levels, while increasing the dissolved Ca2+ concentration. Solution pH decreased linearly with increasing Ca2+ dose, from 9.0 with no added Ca2+, to about 8.4 at a dose of 200 mg·L-1. Alkalinity decreased from 10.5 to about 3.5 meq·L-1, while dissolved Ca2+ levels increased from 20.6 to approximately 100 mg·L-1 over this same dose range. Addition of CaO and Ca(OH)2 had a comparatively small effect on equilibrium chemistry and maintained high pH, high alkalinity and low Ca2+ levels in the water. The kinetics of these changes were quite slow; equilibrium was generally reached between 4-7 days depending upon Ca-salt used and the rate of mixing. The Ca-salt additions resulted in modest (30-40%) reductions in total phosphorus (TP) and chlorophyll levels. Sorption and core-flux experiments demonstrated limited capacity of precipitated CaCO3 to sorb soluble-reactive phosphorus (SRP). More substantial removal was achieved, however, via coprecipitation of SRP with CaCO3 formed in situ from Ca2+-amended recycled water added to Lake Elsinore water, although removal efficiencies remained well below those typically achieved with alum. Based upon these findings, some general recommendations can be made about Ca2+ addition to lakes for the control of phosphorus: (i) Ca2+ addition to lakes will be more effective during periods of high SRP concentrations; (ii) addition of Ca-salts that promote coprecipitation of SRP with CaCO3 formed in situ is more effective at removing SRP from the water column than adsorption to preformed CaCO3; and (iii) the form and dose of the Ca-salt dramatically influences the final chemical condition of the water.
Flood-related, Organic-carbon Anomalies as Possible Temporal Markers in Reservoir Bottom SedimentsKyle E. JuracekLake and Reservoir Management1040-23810743-81412042004 309 - 321Flood-related, Organic-carbon Anomalies as Possible Temporal Markers in Reservoir Bottom Sediments Author: Kyle E. Juraceka Abstract Results of a study of sediment cores from four reservoirs in the upper Mississippi River Basin, USA, indicated that anomalous organic carbon concentrations associated with flood deposits may provide detectable temporal markers in reservoir bottom sediments. Temporal markers are needed for reservoir sediment studies to date sediment layers deposited between the 1963-64 cesium-137 peak and the present. For two of four reservoirs studied, anomalously low organic carbon concentrations were measured for a sample interval in the upper part of a sediment core. The anomalous interval was interpreted to have been deposited during the July 1993 flood that affected a large area of the upper Mississippi River Basin. Potentially, the July 1993 flood deposit may be used as a temporal marker in reservoir bottom sediments in parts of the basin affected by the flood. Several uncertainties remain regarding the viability of organic carbon as a temporal marker including the combination of flood, basin, and reservoir characteristics required to produce a recognizable organic carbon marker in the bottom sediment and the optimal sampling strategy needed to detect the marker in a sediment core. It is proposed that flood duration and basin size may be important factors as to whether or not an anomalous and detectable organic carbon layer is deposited in a reservoir. Keywords: organic carbon; anomaly; flood; age dating; reservoir; sediment View Full Text ArticleSubscribe Affiliation: a U.S. Geological Survey, Lawrence, Kansas, USA DOI: 10.1080/07438140409354160 Published in: Lake and Reservoir Management, Volume 20, Issue 4 December 2004 , pages 309 - 321 Publication Frequency: 4 issues per year First Published on: 01 December 2004 Formats available: PDF (English) Results of a study of sediment cores from four reservoirs in the upper Mississippi River Basin, USA, indicated that anomalous organic carbon concentrations associated with flood deposits may provide detectable temporal markers in reservoir bottom sediments. Temporal markers are needed for reservoir sediment studies to date sediment layers deposited between the 1963-64 cesium-137 peak and the present. For two of four reservoirs studied, anomalously low organic carbon concentrations were measured for a sample interval in the upper part of a sediment core. The anomalous interval was interpreted to have been deposited during the July 1993 flood that affected a large area of the upper Mississippi River Basin. Potentially, the July 1993 flood deposit may be used as a temporal marker in reservoir bottom sediments in parts of the basin affected by the flood. Several uncertainties remain regarding the viability of organic carbon as a temporal marker including the combination of flood, basin, and reservoir characteristics required to produce a recognizable organic carbon marker in the bottom sediment and the optimal sampling strategy needed to detect the marker in a sediment core. It is proposed that flood duration and basin size may be important factors as to whether or not an anomalous and detectable organic carbon layer is deposited in a reservoir.
Phosphorus Dynamics in Jessie Lake: Mass Flux Across the Sediment-Water InterfaceHong Wang; Miki Hondzo; Brenda Stauffer; Bruce WilsonLake and Reservoir Management1040-23810743-81412042004 333 - 346Phosphorus Dynamics in Jessie Lake: Mass Flux Across the Sediment-Water Interface Authors: Hong Wanga; Miki Hondzob; Brenda Staufferc; Bruce Wilsond Abstract Field and laboratory measurements were conducted to determine phosphorus (P) fluxes at the sediment-water interface in a thermally stratified lake. High energy dissipation rates with oscillatory fluid-flow velocities of ±0.05 m/sec were observed above the sediment-water interface at the depth of 12 m. Although the lake exhibits periods with thermal polymixis, dissolved oxygen (DO) usually exhibits a year-to-year summer clinograde DO pattern with anaerobic conditions typically encountered below 5 m to 6 m depth. In 2001, the lake was weakly dimictic with a turbulent benthic boundary layer dominated by anaerobic conditions with a pH range from 7.2 to 8.4. The concentration of P-affinity metals in the sediments ranged from 1.5 to 16.1 mg g-1, represented by Fe, Al, and Ca. The lake has relatively low P-affinity metal concentrations in the sediments, implying a low holding capacity of P. Phosphorus flux at the sediment-water interface was mediated by DO concentrations in the water column. Under aerobic conditions, no release flux of phosphorus was observed in the water column. Under anaerobic conditions, the measured release flux of P from the sediments to the overlying water was 16.93 mg·m-2·day-1. A sediment P dynamic model was used to predict conduct long-term P internal loading in the lake. If organic loading to the lake sediments continues at the rate observed in the recent past, the internal loading of P was predicted to nearly double in the next 30 years. The reduction in the organic loading of 1%, 5%, 10% and 25% will achieve reductions in the P internal loading to 9.7,3.0,0.7, and 0 mg·m-2·mday-1, respectively. Hence, future lake management options may focus on incrementally reducing internally derived P loading that will, in turn, reduce organic loading within Jessie Lake. Keywords: phosphorus; mobilization; release; sediments; fractionation; flux; internal loading View Full Text ArticleSubscribe Affiliations: a Metropolitan Council Environmental Services, St. Paul, MN b Department of Civil Engineering, St. Anthony Falls Laboratory, University of Minnesota, MN c U.S. Forest Service, Walker, MN d Minnesota Pollution Control Agency, St. Paul, MN DOI: 10.1080/07438140409354162 Published in: Lake and Reservoir Management, Volume 20, Issue 4 December 2004 , pages 333 - 346 Publication Frequency: 4 issues per year First Published on: 01 December 2004 Formats available: PDF (English) Field and laboratory measurements were conducted to determine phosphorus (P) fluxes at the sediment-water interface in a thermally stratified lake. High energy dissipation rates with oscillatory fluid-flow velocities of ±0.05 m/sec were observed above the sediment-water interface at the depth of 12 m. Although the lake exhibits periods with thermal polymixis, dissolved oxygen (DO) usually exhibits a year-to-year summer clinograde DO pattern with anaerobic conditions typically encountered below 5 m to 6 m depth. In 2001, the lake was weakly dimictic with a turbulent benthic boundary layer dominated by anaerobic conditions with a pH range from 7.2 to 8.4. The concentration of P-affinity metals in the sediments ranged from 1.5 to 16.1 mg g-1, represented by Fe, Al, and Ca. The lake has relatively low P-affinity metal concentrations in the sediments, implying a low holding capacity of P. Phosphorus flux at the sediment-water interface was mediated by DO concentrations in the water column. Under aerobic conditions, no release flux of phosphorus was observed in the water column. Under anaerobic conditions, the measured release flux of P from the sediments to the overlying water was 16.93 mg·m-2·day-1. A sediment P dynamic model was used to predict conduct long-term P internal loading in the lake. If organic loading to the lake sediments continues at the rate observed in the recent past, the internal loading of P was predicted to nearly double in the next 30 years. The reduction in the organic loading of 1%, 5%, 10% and 25% will achieve reductions in the P internal loading to 9.7,3.0,0.7, and 0 mg·m-2·mday-1, respectively. Hence, future lake management options may focus on incrementally reducing internally derived P loading that will, in turn, reduce organic loading within Jessie Lake.
ErratumLake and Reservoir Management1040-23810743-81412042004269Erratum View Full Text ArticleSubscribe DOI: 10.1080/07438140409354156 Published in: Lake and Reservoir Management, Volume 20, Issue 4 December 2004 , page 269 Publication Frequency: 4 issues per year First Published on: 01 December 2004 Formats available: PDF (English)
Small-Plot, Low-Dose Treatments of Triclopyr for Selective Control of Eurasian WatermilfoilAngela G. Poovey; Kurt D. Getsinger; John G. Skogerboe; Tyler J. Koschnick; John D. Madsen; R. Michael StewartLake and Reservoir Management1040-23810743-81412042004 322 - 332Small-Plot, Low-Dose Treatments of Triclopyr for Selective Control of Eurasian Watermilfoil Authors: Angela G. Pooveya; Kurt D. Getsingera; John G. Skogerboea; Tyler J. Koschnickb; John D. Madsenc; R. Michael Stewartd Abstract Small-plot treatments of triclopyr were conducted on Lake Minnetonka and Lake Minnewashta, MN, during June 1998 to investigate the herbicide's potential to selectively control Eurasian watermilfoil (Myriophyllum spicatum L.) at low doses. Applications were made on 1-ha plots with rates based on plot type: references (0 mg acid equivalent (ae)·L-1), protected plots (0.5 mg ae·L-1), semi-protected plots(1.0 mgae·L-1), and unprotected plots (1.5 mgae·L-1). Plot protection was a function of potential mixing in the water column. Herbicide residues were monitored to determine dissipation 1 through 72 h post treatment. Samples were analyzed with both a high performance liquid chromatography technique and an enzyme-linked immunosorbent assay method. Results from these two analytical techniques were compared, and found equivalent (R2 = 0.96). Triclopyr had a relatively short half-life for each treatment (3.5 hr at 0.5 mg ae·L-1, 2.9 hr at 1.0 mg ae·L-1, and 4.2 hr at 1.5 mg ae·L-1). At 8 weeks post treatment, there was a 30 to 45% reduction in Eurasian watermilfoil distribution. Greatest Eurasian watermilfoil control was achieved in plots using higher triclopyr rates. Frequency of native plants decreased by 24% in the untreated reference plot, 20% in the 0.5 mg ae·L-1 plot and 6% in the 1.0 and 1.5 mg ae·L-1 plots. Mean species per point, however, either increased or remained unchanged in seven of the nine treated plots. Decline of native plants may be partially attributed to the onset of fall senescence. Larger contiguous areas, higher triclopyr rates, and sequential applications may be required to enhance Eurasian watermilfoil control in small-plot, partial lake treatments. Keywords: aquatic plant control; Myriophyllum spicatum; herbicide; Renovate®3; ELISA View Full Text ArticleSubscribe Affiliations: a U.S. Army Engineer Research and Development Center, Environmental Laboratory, Vicksburg, MS b Center for Aquatic and Invasive Plants, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL c Mississippi State University, GeoResources Institute, Mississippi State, MS d U.S. Army Engineer District, Vicksburg, Vicksburg, MS DOI: 10.1080/07438140409354161 Published in: Lake and Reservoir Management, Volume 20, Issue 4 December 2004 , pages 322 - 332 Publication Frequency: 4 issues per year First Published on: 01 December 2004 Formats available: PDF (English) Small-plot treatments of triclopyr were conducted on Lake Minnetonka and Lake Minnewashta, MN, during June 1998 to investigate the herbicide's potential to selectively control Eurasian watermilfoil (Myriophyllum spicatum L.) at low doses. Applications were made on 1-ha plots with rates based on plot type: references (0 mg acid equivalent (ae)·L-1), protected plots (0.5 mg ae·L-1), semi-protected plots(1.0 mgae·L-1), and unprotected plots (1.5 mgae·L-1). Plot protection was a function of potential mixing in the water column. Herbicide residues were monitored to determine dissipation 1 through 72 h post treatment. Samples were analyzed with both a high performance liquid chromatography technique and an enzyme-linked immunosorbent assay method. Results from these two analytical techniques were compared, and found equivalent (R2 = 0.96). Triclopyr had a relatively short half-life for each treatment (3.5 hr at 0.5 mg ae·L-1, 2.9 hr at 1.0 mg ae·L-1, and 4.2 hr at 1.5 mg ae·L-1). At 8 weeks post treatment, there was a 30 to 45% reduction in Eurasian watermilfoil distribution. Greatest Eurasian watermilfoil control was achieved in plots using higher triclopyr rates. Frequency of native plants decreased by 24% in the untreated reference plot, 20% in the 0.5 mg ae·L-1 plot and 6% in the 1.0 and 1.5 mg ae·L-1 plots. Mean species per point, however, either increased or remained unchanged in seven of the nine treated plots. Decline of native plants may be partially attributed to the onset of fall senescence. Larger contiguous areas, higher triclopyr rates, and sequential applications may be required to enhance Eurasian watermilfoil control in small-plot, partial lake treatments.
Biomanipulation: A Classic Example in a Shallow Eutrophic PondMatthew F. Albright; Willard N. Harman; Wesley T. Tibbits; Michael S. Gray; David M. Warner; Rebecca J. HamwayLake and Reservoir Management1040-23810743-81412042004 263 - 269Biomanipulation: A Classic Example in a Shallow Eutrophic Pond Authors: Matthew F. Albrighta; Willard N. Harmana; Wesley T. Tibbitsa; Michael S. Graya; David M. Warnerb; Rebecca J. Hamwayc Abstract Mod Pond, Otsego County, New York, is an artificial impoundment created by the damming of a natural wetland in 1939. It was dominated by blue-green algal blooms between at least 1970-1998. During that time a few scattered clones of sedges (Cyperaceae) along the shoreline were the only vascular plants present. The zooplankton community was dominated by small individuals, primarily rotifers, which were unable to effectively graze the algal community. During this interval, golden shiner (Notemigonus crysoleucas) and brown bullhead (Ictalurus nebulosus) made up the entire fish community. Largemouth and smallmouth bass (Micropterus dolomieu and M. salmoides) were added between 1998 and spring 1999. Golden shiner recruitment functionally ended at that time, and by 2002 they had been virtually eliminated. Secchi transparencies increased and mean chlorophyll a decreased significantly (p<0.05), with algal blooms becoming practically nonexistent. Water weed (Elodea canadensis) nowcovers the bottom of most of the pond, reaching the surface in many areas up to 2 m in depth. Increased transparency, as well as potential changes in nutrient dynamics, both indirectly brought about by the addition of piscivorous fish, apparently has enabled Elodea to out-compete plank tonic algae for available nutrients. This documents a situation where top-down management of the fish community has affected the biota and water quality through trophic cascades. The introduction of piscivorous fish (top-down management) may be used to manage water quality through increased algal grazing by zooplankton. However, a substantial increase in macrophytes, as documented here, may be an outcome. Keywords: biomanipulation; trophic cascade; top-down management; eutrophic pond; golden shiner; piscivory View Full Text ArticleSubscribe Affiliations: a State University of New York College at Oneonta Biological Field Station, Cooperstown, NY b Department of Natural Resources, Cornell University Biological Field Station, Bridgeport, NY c Dickinson College, Carlisle, PA DOI: 10.1080/07438140409354155 Published in: Lake and Reservoir Management, Volume 20, Issue 4 December 2004 , pages 263 - 269 Publication Frequency: 4 issues per year First Published on: 01 December 2004 Formats available: PDF (English) Mod Pond, Otsego County, New York, is an artificial impoundment created by the damming of a natural wetland in 1939. It was dominated by blue-green algal blooms between at least 1970-1998. During that time a few scattered clones of sedges (Cyperaceae) along the shoreline were the only vascular plants present. The zooplankton community was dominated by small individuals, primarily rotifers, which were unable to effectively graze the algal community. During this interval, golden shiner (Notemigonus crysoleucas) and brown bullhead (Ictalurus nebulosus) made up the entire fish community. Largemouth and smallmouth bass (Micropterus dolomieu and M. salmoides) were added between 1998 and spring 1999. Golden shiner recruitment functionally ended at that time, and by 2002 they had been virtually eliminated. Secchi transparencies increased and mean chlorophyll a decreased significantly (p<0.05), with algal blooms becoming practically nonexistent. Water weed (Elodea canadensis) nowcovers the bottom of most of the pond, reaching the surface in many areas up to 2 m in depth. Increased transparency, as well as potential changes in nutrient dynamics, both indirectly brought about by the addition of piscivorous fish, apparently has enabled Elodea to out-compete plank tonic algae for available nutrients. This documents a situation where top-down management of the fish community has affected the biota and water quality through trophic cascades. The introduction of piscivorous fish (top-down management) may be used to manage water quality through increased algal grazing by zooplankton. However, a substantial increase in macrophytes, as documented here, may be an outcome.
The Phosphorus-Chlorophyll Relationship in Lakes: Potential Influences of Color and Mixing RegimeKarl E. Havens; Gertrud K. NürnbergLake and Reservoir Management1040-23810743-81412032004 188 - 196The Phosphorus-Chlorophyll Relationship in Lakes: Potential Influences of Color and Mixing Regime Authors: Karl E. Havensa; Gertrud K. Nrnbergb Abstract We used summer epilimnetic means from a large dataset (369 lakes from North America, Europe, Asia, and New Zealand) to examine whether color or mixing regime significantly influence the log-log relationship between chlorophyll a (Chl a) and total phosphorus (TP) in lakes. We found no significant difference in regression models for clear (color < 10 Pt units) vs. humic lakes (color > 20 Pt units), even when data were screened so that both types of lakes were represented by the same range of TP. Likewise, there was no significant difference in regression models for mixed vs. thermally stratified lakes. Knowing that a particular lake is clear vs. humic, or mixed vs. stratified, therefore is not helpful in developing a predictive model of Chl a from TP. However, when we simultaneously considered water color and mixing regime, a potentially useful feature was identified. Mixed humic lakes have a somewhat lower (significant at p = 0.10) ratio of Chl a / TP than mixed clear water lakes, whereas no such difference exists between humic and clear water lakes that are thermally stratified. Likewise, when we plotted the Chl a / TP ratio vs. color, there was a negative slope for mixed lakes, but no significant relationship for stratified lakes. We suggest that in stratified humic lakes, which are often sheltered deep systems with a high Osgood Ratio, phytoplankton can compensate for reduced underwater irradiance by migrating toward the water surface, whereas in mixed humic lakes, that response is not possible. Lake managers dealing with mixed humic lakes might expect a lower yield of Chl a / TP than in mixed clear water lakes. Further research is needed to test this hypothesis. In any case, caution is warranted when applying such results to lake management, because given the numerous effects of high P inputs (e.g., changes in benthic invertebrate communities, biological oxygen demand, and sediment metabolism) it is unwise to focus solely on the Chl a response to protect water quality. Keywords: phosphorus-chlorophyll regression; color; mixing regime; predictive models View Full Text ArticleSubscribe Affiliations: a South Florida Water Management District, West Palm Beach, Florida, USA b Freshwater Research, Baysville, Ontario, Canada DOI: 10.1080/07438140409354243 Published in: Lake and Reservoir Management Publication Frequency: 4 issues per year First Published on: 01 September 2004 Formats available: PDF (English) We used summer epilimnetic means from a large dataset (369 lakes from North America, Europe, Asia, and New Zealand) to examine whether color or mixing regime significantly influence the log-log relationship between chlorophyll a (Chl a) and total phosphorus (TP) in lakes. We found no significant difference in regression models for clear (color < 10 Pt units) vs. humic lakes (color > 20 Pt units), even when data were screened so that both types of lakes were represented by the same range of TP. Likewise, there was no significant difference in regression models for mixed vs. thermally stratified lakes. Knowing that a particular lake is clear vs. humic, or mixed vs. stratified, therefore is not helpful in developing a predictive model of Chl a from TP. However, when we simultaneously considered water color and mixing regime, a potentially useful feature was identified. Mixed humic lakes have a somewhat lower (significant at p = 0.10) ratio of Chl a / TP than mixed clear water lakes, whereas no such difference exists between humic and clear water lakes that are thermally stratified. Likewise, when we plotted the Chl a / TP ratio vs. color, there was a negative slope for mixed lakes, but no significant relationship for stratified lakes. We suggest that in stratified humic lakes, which are often sheltered deep systems with a high Osgood Ratio, phytoplankton can compensate for reduced underwater irradiance by migrating toward the water surface, whereas in mixed humic lakes, that response is not possible. Lake managers dealing with mixed humic lakes might expect a lower yield of Chl a / TP than in mixed clear water lakes. Further research is needed to test this hypothesis. In any case, caution is warranted when applying such results to lake management, because given the numerous effects of high P inputs (e.g., changes in benthic invertebrate communities, biological oxygen demand, and sediment metabolism) it is unwise to focus solely on the Chl a response to protect water quality.
Biomanipulation: A Classic Example in a Shallow Eutrophic PondMatthew F. Albright; Willard N. Harman; Wesley T. Tibbits; Michael S. Gray; David M. Warner; Rebecca J. HamwayLake and Reservoir Management1040-23810743-81412032004 181 - 187Biomanipulation: A Classic Example in a Shallow Eutrophic Pond Authors: Matthew F. Albrighta; Willard N. Harmana; Wesley T. Tibbitsa; Michael S. Graya; David M. Warnerb; Rebecca J. Hamwayc Abstract Moe Pond, Otsego County, New York, is an artificial impoundment created by the damming of a natural wetland in 1939. It was dominated by blue-green algal blooms between at least 1970-1998. During that time a few scattered clones of sedges (Cyperaceae) along the shoreline were the only vascular plants present. The zooplankton community was dominated by small individuals, primarily rotifers, which were unable to effectively graze the algal community. During this interval, golden shiner (Notemigonus crysoleucas) and brown bullhead (Ictalurus nebulosus) made up the entire fish community. Largemouth and smallmouth bass (Micropterus dolomieu and M. salmoides) were added between 1998 and spring 1999. Golden shiner recruitment functionally ended at that time, and by 2002 they had been virtually eliminated. Secchi transparencies increased and mean chlorophyll a decreased significantly (p<0.05), with algal blooms becoming practically nonexistent. Water weed (Elodea canadensis) now covers the bottom of most of the pond, reaching the surface in many areas up to 2 m in depth. Increased transparency, as well as potential changes in nutrient dynamics, both indirectly brought about by the addition of piscivorous fish, apparently has enabled Elodea to out-compete plank tonic algae for available nutrients. This documents a situation where top-down management of the fish community has affected the biota and water quality through trophic cascades. The introduction of piscivorous fish (top-down management) may be used to manage water quality through increased algal grazing by zooplankton. However, a substantial increase in macrophytes, as documented here, may be an outcome. Keywords: biomanipulation; trophic cascade; top-down management; eutrophic pond; golden shiner; piscivory View Full Text ArticleSubscribe Affiliations: a State University of New York College at Oneonta Biological Field Station, Cooperstown, NY b Department of Natural Resources, Cornell University Biological Field Station, Bridgeport, NY c Dickinson College, Carlisle, PA DOI: 10.1080/07438140409354242 Published in: Lake and Reservoir Management, Volume 20, Issue 3 September 2004 , pages 181 - 187 Publication Frequency: 4 issues per year First Published on: 01 September 2004 Formats available: PDF (English) Moe Pond, Otsego County, New York, is an artificial impoundment created by the damming of a natural wetland in 1939. It was dominated by blue-green algal blooms between at least 1970-1998. During that time a few scattered clones of sedges (Cyperaceae) along the shoreline were the only vascular plants present. The zooplankton community was dominated by small individuals, primarily rotifers, which were unable to effectively graze the algal community. During this interval, golden shiner (Notemigonus crysoleucas) and brown bullhead (Ictalurus nebulosus) made up the entire fish community. Largemouth and smallmouth bass (Micropterus dolomieu and M. salmoides) were added between 1998 and spring 1999. Golden shiner recruitment functionally ended at that time, and by 2002 they had been virtually eliminated. Secchi transparencies increased and mean chlorophyll a decreased significantly (p<0.05), with algal blooms becoming practically nonexistent. Water weed (Elodea canadensis) now covers the bottom of most of the pond, reaching the surface in many areas up to 2 m in depth. Increased transparency, as well as potential changes in nutrient dynamics, both indirectly brought about by the addition of piscivorous fish, apparently has enabled Elodea to out-compete plank tonic algae for available nutrients. This documents a situation where top-down management of the fish community has affected the biota and water quality through trophic cascades. The introduction of piscivorous fish (top-down management) may be used to manage water quality through increased algal grazing by zooplankton. However, a substantial increase in macrophytes, as documented here, may be an outcome.
Relations Between Water Chemistry and Water Quality as Defined by Lake Users in FloridaMark V. Hoyer; Claude D. Brown; Daniel E. Canfield Jr.Lake and Reservoir Management1040-23810743-81412032004 240 - 248Relations Between Water Chemistry and Water Quality as Defined by Lake Users in Florida Authors: Mark V. Hoyera; Claude D. Browna; Daniel E. Canfield Jr.a Abstract A lake user survey was conducted on 116 Florida lakes concurrent with citizens' water sampling activities. Results showed there were significant relations between lake users perceptions of physical condition of water and associated lake trophic state water chemistry variables. There were also significant relations between lake users perceptions of recreational and aesthetic enjoyment of water and associated lake trophic state water chemistry variables. While the relations reported in this study were significant there was also a lot of variance in actual water chemistry for any perceived water quality. Some of this variance was attributed to regional differences in perceptions of water quality. Before this type of survey is used for lake management activities in Florida, it is recommended to expand the number of individuals surveyed per lake, especially from multiple lake users to better understand the variance in water chemistry around perceived water quality. It is also recommended to add questions pertaining to additional lake uses including activities like fishing, bird watching and other wildlife related uses. Keywords: lake user survey; citizen monitoring; lake trophic state View Full Text ArticleSubscribe Affiliation: a Department of Fisheries and Aquatic Sciences, University of Florida Gainesville, Gainesville, FL, USA DOI: 10.1080/07438140409354247 Published in: Lake and Reservoir Management, Volume 20, Issue 3 September 2004 , pages 240 - 248 Publication Frequency: 4 issues per year First Published on: 01 September 2004 Formats available: PDF (English) A lake user survey was conducted on 116 Florida lakes concurrent with citizens' water sampling activities. Results showed there were significant relations between lake users perceptions of physical condition of water and associated lake trophic state water chemistry variables. There were also significant relations between lake users perceptions of recreational and aesthetic enjoyment of water and associated lake trophic state water chemistry variables. While the relations reported in this study were significant there was also a lot of variance in actual water chemistry for any perceived water quality. Some of this variance was attributed to regional differences in perceptions of water quality. Before this type of survey is used for lake management activities in Florida, it is recommended to expand the number of individuals surveyed per lake, especially from multiple lake users to better understand the variance in water chemistry around perceived water quality. It is also recommended to add questions pertaining to additional lake uses including activities like fishing, bird watching and other wildlife related uses.
A Comparison of Fish and Aquatic Plant Assemblages to Assess Ecological Health of Small Wisconsin LakesGene R. Hatzenbeler; Jeffrey M. Kampa; Martin J. Jennings; Edward E. EmmonsLake and Reservoir Management1040-23810743-81412032004 211 - 218A Comparison of Fish and Aquatic Plant Assemblages to Assess Ecological Health of Small Wisconsin Lakes Authors: Gene R. Hatzenbelera; Jeffrey M. Kampaa; Martin J. Jenningsa; Edward E. Emmonsb Abstract Biological monitoring uses assemblage structure to assess condition of ecological systems. Taxa that effectively integrate impacts within the system of interest are useful for biological monitoring, whereas taxa that do not demonstrate predictable responses can provide ambiguous or misleading indicators. We compared the effectiveness of aquatic plant and fish assemblages for biological monitoring in 16 small lakes (< 80 ha). The lakes were limnologically similar but differed in extent of lakeshore development and type of watershed land-cover. Linear regression analysis revealed that the quality of the aquatic plant community declined with increasing lakeshore development (number of dwellings per km of shoreline), which is the primary source of impacts within this group of northern Wisconsin lakes. As lakeshore development increased, we observed a decrease in the Floristic Quality Index (FQI) of a lake, number of plant species per lake, number of highly intolerant plant species per lake, and the species richness and frequency of occurrence of floating vegetation. Conversely, fish species richness, centrarchid species richness, number of small benthic fish species, intolerant fish species richness and the proportion of the total catch of intolerant and vegetative-dwelling fish were not related to lakeshore development. These results indicate that, within the range of conditions observed, aquatic plant communities are more sensitive to lakeshore development than fish communities. Neither aquatic plant species composition nor fish assemblage variables were correlated with watershed land cover types; however all the watersheds were relatively small and undisturbed. In small lakes with few fish species, aquatic plants can be used as biological indicators for monitoring ecological conditions. Keywords: monitoring; lakes; fish; aquatic plants; development; land-cover; FQI; IBI View Full Text ArticleSubscribe Affiliations: a Wisconsin Department of Natural Resources, Bureau of Integrated Science Services, Spooner, WI b Wisconsin Department of Natural Resources, Bureau of Integrated Science Services, Monona, WI DOI: 10.1080/07438140409354245 Published in: Lake and Reservoir Management, Volume 20, Issue 3 September 2004 , pages 211 - 218 Publication Frequency: 4 issues per year First Published on: 01 September 2004 Formats available: PDF (English) Biological monitoring uses assemblage structure to assess condition of ecological systems. Taxa that effectively integrate impacts within the system of interest are useful for biological monitoring, whereas taxa that do not demonstrate predictable responses can provide ambiguous or misleading indicators. We compared the effectiveness of aquatic plant and fish assemblages for biological monitoring in 16 small lakes (< 80 ha). The lakes were limnologically similar but differed in extent of lakeshore development and type of watershed land-cover. Linear regression analysis revealed that the quality of the aquatic plant community declined with increasing lakeshore development (number of dwellings per km of shoreline), which is the primary source of impacts within this group of northern Wisconsin lakes. As lakeshore development increased, we observed a decrease in the Floristic Quality Index (FQI) of a lake, number of plant species per lake, number of highly intolerant plant species per lake, and the species richness and frequency of occurrence of floating vegetation. Conversely, fish species richness, centrarchid species richness, number of small benthic fish species, intolerant fish species richness and the proportion of the total catch of intolerant and vegetative-dwelling fish were not related to lakeshore development. These results indicate that, within the range of conditions observed, aquatic plant communities are more sensitive to lakeshore development than fish communities. Neither aquatic plant species composition nor fish assemblage variables were correlated with watershed land cover types; however all the watersheds were relatively small and undisturbed. In small lakes with few fish species, aquatic plants can be used as biological indicators for monitoring ecological conditions.
Impacts of Metal Salt Addition on the Chemistry of Lake Elsinore, California: 1. AlumMichael A. AndersonLake and Reservoir Management1040-23810743-81412032004 249 - 258Impacts of Metal Salt Addition on the Chemistry of Lake Elsinore, California: 1. Alum Author: Michael A. Andersona Abstract A series of laboratory studies were conducted to evaluate the impacts of alum addition on the water chemistry of Lake Elsinore. Lake Elsinore is a warm, shallow, polymictic and eutrophic lake, located in southwest Riverside County in Southern California, that is plagued with chronic poor water quality conditions due in part to large internal nutrient loadings. The lake also possesses a high pH and high alkalinity. Control of internal phosphorus loading by alum was considered as a possible control method, although most alum applications have been made in relatively soft water lakes. The changes in water chemistry resulting from alum and high-acid alum treatments were quantified for 3 different Al doses (9, 13 and 18 mg L-1). The high alkalinity in the lake limited the capacity for alum at the 9 mg L-1 Al dose to reduce the equilibrium pH below 8.7. High acid alum formulations and higher Al doses were somewhat more successful at lowering the pH, however. For example, Al doses of 9 mg L-1+20% H2SO4 and 18 mg L-1 (no free acid) were able to lower the pH to approximately 8.5. The highest dose and free-acid content (18 mg L-1+20% H2SO4) was most effective, lowering the pH to about 8. Dissolved Al concentrations varied strongly as a function of Al dose, percent free acid in the high-acid alum formulations, and time. Dissolved Al concentrations increased with increasing pH, and approached (or exceeded) 2 mg L-1 in some samples, but generally remained below levels predicted by the solubility of amorphous Al(OH)3. pH and dissolved Al concentrations both varied markedly over time, due to kinetic limitations to CO2 outgassing. Dissolved Al concentrations monitored in longer-term core experiments decreased over time, suggesting transformation of amorphous, high-solubility Al phase(s) to more crystalline, lower-solubility phases. The high Al solubility and potential toxicity makes alum treatment inappropriate for Lake Elsinore and other strongly alkaline lakes. Keywords: alum; chemistry; Lake Elsinore View Full Text ArticleSubscribe Affiliation: a Department of Environmental Sciences, University of California, Riverside, CA DOI: 10.1080/07438140409354248 Published in: Lake and Reservoir Management, Volume 20, Issue 3 September 2004 , pages 249 - 258 Publication Frequency: 4 issues per year First Published on: 01 September 2004 Formats available: PDF (English) A series of laboratory studies were conducted to evaluate the impacts of alum addition on the water chemistry of Lake Elsinore. Lake Elsinore is a warm, shallow, polymictic and eutrophic lake, located in southwest Riverside County in Southern California, that is plagued with chronic poor water quality conditions due in part to large internal nutrient loadings. The lake also possesses a high pH and high alkalinity. Control of internal phosphorus loading by alum was considered as a possible control method, although most alum applications have been made in relatively soft water lakes. The changes in water chemistry resulting from alum and high-acid alum treatments were quantified for 3 different Al doses (9, 13 and 18 mg L-1). The high alkalinity in the lake limited the capacity for alum at the 9 mg L-1 Al dose to reduce the equilibrium pH below 8.7. High acid alum formulations and higher Al doses were somewhat more successful at lowering the pH, however. For example, Al doses of 9 mg L-1+20% H2SO4 and 18 mg L-1 (no free acid) were able to lower the pH to approximately 8.5. The highest dose and free-acid content (18 mg L-1+20% H2SO4) was most effective, lowering the pH to about 8. Dissolved Al concentrations varied strongly as a function of Al dose, percent free acid in the high-acid alum formulations, and time. Dissolved Al concentrations increased with increasing pH, and approached (or exceeded) 2 mg L-1 in some samples, but generally remained below levels predicted by the solubility of amorphous Al(OH)3. pH and dissolved Al concentrations both varied markedly over time, due to kinetic limitations to CO2 outgassing. Dissolved Al concentrations monitored in longer-term core experiments decreased over time, suggesting transformation of amorphous, high-solubility Al phase(s) to more crystalline, lower-solubility phases. The high Al solubility and potential toxicity makes alum treatment inappropriate for Lake Elsinore and other strongly alkaline lakes.
Impacts, Perceptions, and Management of Shoreline Hazards and Water Levels on a Fluctuating Reservoir: A Case Study of the Winnebago System, WisconsinAnthony O. GabrielLake and Reservoir Management1040-23810743-81412032004 197 - 210Impacts, Perceptions, and Management of Shoreline Hazards and Water Levels on a Fluctuating Reservoir: A Case Study of the Winnebago System, Wisconsin Author: Anthony O. Gabriela Abstract This paper provides the results of a mail survey of 872 residential property owners along the shorelines of the Winnebago System, Wisconsin that determined their hazard experiences, adjustments, and management preferences in regards to fluctuating water levels. While half of the respondents were aware of hazard potentials prior to purchase, properties have been impacted by a range of shoreline hazards from flooding (27%) to high water levels (54%). Principally caused by a combination of storm-driven waves and high water levels, hazard damages are hazard-specific, and tend to relate to either the shoreline directly (e.g. loss of beach, lawn and garden damage) or to structures directly on the shoreline (e.g. shore protection or docks). Similar to other systems, many residents have resorted to structural hazard adjustments, generally as a response to erosion or high water levels. The majority of property owners indicated a preference for water level regulation to reduce shoreline hazards. However, the majority of respondents also would prefer the water levels to remain the same, while the remaining respondents were extremely divided between the various options for target summer and winter water levels, actually preferring levels that would increase hazard potentials. There is a need for a public education program on the Winne bago System that focuses on publicizing the technical limitations of lake level regulation to reduce hazard losses, the range of alternative hazard adjustment strategies, and the financial and technical assistance for hazard management available from various government agencies. Keywords: reservoir; hazard; erosion; flooding; water levels; management; Wisconsin; perception View Full Text ArticleSubscribe Affiliation: a Department of Geography and Land Studies, Central Washington University, Ellensburg, WA DOI: 10.1080/07438140409354244 Published in: Lake and Reservoir Management, Volume 20, Issue 3 September 2004 , pages 197 - 210 Publication Frequency: 4 issues per year First Published on: 01 September 2004 Formats available: PDF (English) This paper provides the results of a mail survey of 872 residential property owners along the shorelines of the Winnebago System, Wisconsin that determined their hazard experiences, adjustments, and management preferences in regards to fluctuating water levels. While half of the respondents were aware of hazard potentials prior to purchase, properties have been impacted by a range of shoreline hazards from flooding (27%) to high water levels (54%). Principally caused by a combination of storm-driven waves and high water levels, hazard damages are hazard-specific, and tend to relate to either the shoreline directly (e.g. loss of beach, lawn and garden damage) or to structures directly on the shoreline (e.g. shore protection or docks). Similar to other systems, many residents have resorted to structural hazard adjustments, generally as a response to erosion or high water levels. The majority of property owners indicated a preference for water level regulation to reduce shoreline hazards. However, the majority of respondents also would prefer the water levels to remain the same, while the remaining respondents were extremely divided between the various options for target summer and winter water levels, actually preferring levels that would increase hazard potentials. There is a need for a public education program on the Winne bago System that focuses on publicizing the technical limitations of lake level regulation to reduce hazard losses, the range of alternative hazard adjustment strategies, and the financial and technical assistance for hazard management available from various government agencies.
Fish Assemblages of Reservoirs, Illustrated by Lake Texoma (Oklahoma-Texas, USA) as a Representative SystemWilliam J. Matthews; Keith B. Gido; Frances P. GelwickLake and Reservoir Management1040-23810743-81412032004 219 - 239Fish Assemblages of Reservoirs, Illustrated by Lake Texoma (Oklahoma-Texas, USA) as a Representative System Authors: William J. Matthewsa; Keith B. Gidob; Frances P. Gelwickc Abstract We suggest six generalizations about the ecology of fishes of large, warm, reservoirs in the southern United States. We test these postulates with examples from more than 20 years of our studies in Lake Texoma (Oklahoma-Texas), and previous historic work in this impoundment. Such impoundments are dynamic systems in which precise predictions about fish faunas, local assemblages, or their potential effects in river-reservoir ecosystems are difficult. However, several generalizations can be supported: (1) fish faunas in reservoirs are a largely non-coevolved array of species, consisting of native and non-native species that may remain relatively unchanged for decades; (2) the fish fauna of a reservoir changes in response to introduction of some non-native species but not others; (3) The fish fauna of a reservoir can change in response to abiotic events that occur at a range of spatial and temporal scales, but effects may be inconsistent and transitory; (4) strong abiotic and biotic gradients in reservoirs influence fish distribution from uplake to downlake and from shallow to deep habitats; (5) Predictability of local fish assemblage structure in reservoirs is low and can vary between littoral and open-water zones; (6) Effects of fish on ecology of the reservoir relates to trophic groups represented, and to numbers of omnivorous fish. Keywords: reservoirs; fishes; fish assemblages; fish faunas; fish distribution; abiotic events; disturbance; long-term changes View Full Text ArticleSubscribe Affiliations: a Department of Zoology and Biological Station, University of Oklahoma, Norman, OK b Division of Biology, Kansas State University, Manhattan, KS c Department of Wildlife and Fisheries Science, Texas A&M University, College Station, TX DOI: 10.1080/07438140409354246 Published in: Lake and Reservoir Management, Volume 20, Issue 3 September 2004 , pages 219 - 239 Publication Frequency: 4 issues per year First Published on: 01 September 2004 Formats available: PDF (English) We suggest six generalizations about the ecology of fishes of large, warm, reservoirs in the southern United States. We test these postulates with examples from more than 20 years of our studies in Lake Texoma (Oklahoma-Texas), and previous historic work in this impoundment. Such impoundments are dynamic systems in which precise predictions about fish faunas, local assemblages, or their potential effects in river-reservoir ecosystems are difficult. However, several generalizations can be supported: (1) fish faunas in reservoirs are a largely non-coevolved array of species, consisting of native and non-native species that may remain relatively unchanged for decades; (2) the fish fauna of a reservoir changes in response to introduction of some non-native species but not others; (3) The fish fauna of a reservoir can change in response to abiotic events that occur at a range of spatial and temporal scales, but effects may be inconsistent and transitory; (4) strong abiotic and biotic gradients in reservoirs influence fish distribution from uplake to downlake and from shallow to deep habitats; (5) Predictability of local fish assemblage structure in reservoirs is low and can vary between littoral and open-water zones; (6) Effects of fish on ecology of the reservoir relates to trophic groups represented, and to numbers of omnivorous fish.
Nutrient Patterns in a Mainstem Reservoir, Kentucky Lake, USA, Over a 10-year PeriodP. M. Yurista; D. S. White; G. W. Kipphut; K. Johnston; G. Rice; S. P. HendricksLake and Reservoir Management1040-23810743-81412022004 148 - 163Nutrient Patterns in a Mainstem Reservoir, Kentucky Lake, USA, Over a 10-year Period Authors: P. M. Yuristaa; D. S. Whiteb; G. W. Kipphutb; K. Johnstonb; G. Riceb; S. P. Hendricksb Abstract Nutrient patterns were examined spatially and temporally from 1989 to 1998 in Kentucky Lake U.S.A., the largest mainstem reservoir on the Tennessee River system. Nutrients included NO3--N, NH4+-N, PO4-, SiO2, SO4-2, and Cl-. Seasonal patterns in most nutrient concentrations were described well by cosine functions. Seasonal descriptions had less variance than discharge related descriptions of nutrient concentrations, possibly due to regulation of reservoir discharge. Differing land-use practices on either side of the reservoir were associated with significantly different nutrient concentrations in their related embayments. The agriculturally dominated western side embayments had lower nutrient concentrations than either the forested eastern side of the reservoir or mainstem sites. Annual average nutrient concentrations did not vary greatly over the 10-year period, indicating no change in eutrophication potential during the sampling period. An exception was a significant decline in SO4-2 levels from 23 mg·L-1 in 1992 to 12.8 mg·L-1 in 1998. Annual export of nutrients was computed from yearly regressions on seasonal concentrations and daily discharge rates. Keywords: reservoirs; nutrients; nutrient cycles; ecological variation; spatial variation; Kentucky Lake; Tennessee River View Full Text ArticleSubscribe Affiliations: a U.S. EPA (MED), Duluth, MN, U.S.A. b Hancock Biological Station, Murray State University, Murray, KY, U.S.A. DOI: 10.1080/07438140409354359 Published in: Lake and Reservoir Management Publication Frequency: 4 issues per year First Published on: 01 June 2004 Formats available: PDF (English) Nutrient patterns were examined spatially and temporally from 1989 to 1998 in Kentucky Lake U.S.A., the largest mainstem reservoir on the Tennessee River system. Nutrients included NO3--N, NH4+-N, PO4-, SiO2, SO4-2, and Cl-. Seasonal patterns in most nutrient concentrations were described well by cosine functions. Seasonal descriptions had less variance than discharge related descriptions of nutrient concentrations, possibly due to regulation of reservoir discharge. Differing land-use practices on either side of the reservoir were associated with significantly different nutrient concentrations in their related embayments. The agriculturally dominated western side embayments had lower nutrient concentrations than either the forested eastern side of the reservoir or mainstem sites. Annual average nutrient concentrations did not vary greatly over the 10-year period, indicating no change in eutrophication potential during the sampling period. An exception was a significant decline in SO4-2 levels from 23 mg·L-1 in 1992 to 12.8 mg·L-1 in 1998. Annual export of nutrients was computed from yearly regressions on seasonal concentrations and daily discharge rates.
Assessing Historical Bathymetry: Kingsmere Lake RevisitedGuy E. Melville; Jonathan K. MelvilleLake and Reservoir Management1040-23810743-81412022004 141 - 147Assessing Historical Bathymetry: Kingsmere Lake Revisited Authors: Guy E. Melvillea; Jonathan K. Melvilleb Abstract Surveys carried out prior to 1950 still constitute our knowledge base for many lakes, particularly those without road access in more remote locations. We assess the accuracy of historical bathymetric data using Kingsmere Lake (Rawson 1936), Prince Albert National Park of Canada, as an example. Rawson presented depth-specific attributes as percents only, which have since formed the basis for management of the lake. In this study, new depths, all spatially referenced, were acquired by sounders along transects. In comparison to Rawson's work, the new areas differ by up to fifty percent because the methods used previously were much less accurate. Volumetric indices are much more similar; the depth-percent volume curves are the same. In using historical data, numerical correction factors for lake areas would probably yield accurate subsurface indices for most lakes. The updated bathymetry for Kingsmere Lake will aid in the determination of Total Allowable Catch for exploited fish species. The bathymetry will also help with watershed activities such as fire management, which affect nutrient loading and ultimately oxygen conditions in the lake. Modern surveys represent the ideal approach, especially for lakes like the MacKenzie Great Lakes. When such studies might occur is uncertain. Rawson, D. S. 1936. J. Biol. Bd. Can. 2:227-284. Keywords: bathymetry; historical data; areal-correction; updated science View Full Text ArticleSubscribe Affiliations: a Aquatic Ecosystems Section, Saskatchewan Research Council and Division of Environmental Engineering, University of Saskatchewan, Saskatoon, SK, Canada b Physical Geography Program, University of Saskatchewan, Saskatoon, SK, Canada DOI: 10.1080/07438140409354358 Published in: Lake and Reservoir Management, Volume 20, Issue 2 June 2004 , pages 141 - 147 Publication Frequency: 4 issues per year First Published on: 01 June 2004 Formats available: PDF (English) Surveys carried out prior to 1950 still constitute our knowledge base for many lakes, particularly those without road access in more remote locations. We assess the accuracy of historical bathymetric data using Kingsmere Lake (Rawson 1936), Prince Albert National Park of Canada, as an example. Rawson presented depth-specific attributes as percents only, which have since formed the basis for management of the lake. In this study, new depths, all spatially referenced, were acquired by sounders along transects. In comparison to Rawson's work, the new areas differ by up to fifty percent because the methods used previously were much less accurate. Volumetric indices are much more similar; the depth-percent volume curves are the same. In using historical data, numerical correction factors for lake areas would probably yield accurate subsurface indices for most lakes. The updated bathymetry for Kingsmere Lake will aid in the determination of Total Allowable Catch for exploited fish species. The bathymetry will also help with watershed activities such as fire management, which affect nutrient loading and ultimately oxygen conditions in the lake. Modern surveys represent the ideal approach, especially for lakes like the MacKenzie Great Lakes. When such studies might occur is uncertain. Rawson, D. S. 1936. J. Biol. Bd. Can. 2:227-284.
Book ReviewJames J. SartorisLake and Reservoir Management1040-23810743-81412022004175Book Review Author: James J. Sartorisa View Full Text ArticleSubscribe Affiliation: a Biological Resources Division, U.S. Geological Survey, Denver, Colorado, USA DOI: 10.1080/07438140409354361 Published in: Lake and Reservoir Management, Volume 20, Issue 2 June 2004 , page 175 Publication Frequency: 4 issues per year First Published on: 01 June 2004 Formats available: PDF (English)
Gasoline-Related Organics in Lake Tahoe Before and After Prohibition of Carbureted Two-Stroke EnginesMichael S. LicoLake and Reservoir Management1040-23810743-81412022004 164 - 174Gasoline-Related Organics in Lake Tahoe Before and After Prohibition of Carbureted Two-Stroke Engines Author: Michael S. Licoa Abstract On June 1, 1999, carbureted two-stroke engines were banned on waters within the Lake Tahoe Basin of California and Nevada. The main gasoline components MTBE (methyl tert-butyl ether) and BTEX (benzene, toluene, ethylbenzene, and xylenes) were present at detectable concentrations in all samples taken from Lake Tahoe during 1997-98 prior to the ban. Samples taken from 1999 through 2001 after the ban contained between 10 and 60 percent of the pre-ban concentrations of these compounds, with MTBE exhibiting the most dramatic change (a 90 percent decrease). MTBE and BTEX concentrations in water samples from Lake Tahoe and Lower Echo Lake were related to the amount of boat use at the sampling sites. Polycyclic aromatic hydrocarbon (PAH) compounds are produced by high-temperature pyrolytic reactions. They were sampled using semipermeable membrane sampling devices in Lake Tahoe and nearby Donner Lake, where carbureted two-stroke engines are legal. PAHs were detected in all samples taken from Lake Tahoe and Donner Lake. The number of PAH compounds and their concentrations are related to boat use. The highest concentrations of PAH were detected in samples from two heavily used boating areas, Tahoe Keys Marina and Donner Lake boat ramp. Other sources of PAH, such as atmospheric deposition, wood smoke, tributary streams, and automobile exhaust do not contribute large amounts of PAH to Lake Tahoe. Similar numbers of PAH compounds and concentrations were found in Lake Tahoe before and after the ban of carbureted two-stroke engines. Keywords: BTEX; MTBE; PAH; two-stroke engines; Lake Tahoe; gasoline View Full Text ArticleSubscribe Affiliation: a United States Geological Survey, Carson City, NV, USA DOI: 10.1080/07438140409354360 Published in: Lake and Reservoir Management, Volume 20, Issue 2 June 2004 , pages 164 - 174 Publication Frequency: 4 issues per year First Published on: 01 June 2004 Formats available: PDF (English) On June 1, 1999, carbureted two-stroke engines were banned on waters within the Lake Tahoe Basin of California and Nevada. The main gasoline components MTBE (methyl tert-butyl ether) and BTEX (benzene, toluene, ethylbenzene, and xylenes) were present at detectable concentrations in all samples taken from Lake Tahoe during 1997-98 prior to the ban. Samples taken from 1999 through 2001 after the ban contained between 10 and 60 percent of the pre-ban concentrations of these compounds, with MTBE exhibiting the most dramatic change (a 90 percent decrease). MTBE and BTEX concentrations in water samples from Lake Tahoe and Lower Echo Lake were related to the amount of boat use at the sampling sites. Polycyclic aromatic hydrocarbon (PAH) compounds are produced by high-temperature pyrolytic reactions. They were sampled using semipermeable membrane sampling devices in Lake Tahoe and nearby Donner Lake, where carbureted two-stroke engines are legal. PAHs were detected in all samples taken from Lake Tahoe and Donner Lake. The number of PAH compounds and their concentrations are related to boat use. The highest concentrations of PAH were detected in samples from two heavily used boating areas, Tahoe Keys Marina and Donner Lake boat ramp. Other sources of PAH, such as atmospheric deposition, wood smoke, tributary streams, and automobile exhaust do not contribute large amounts of PAH to Lake Tahoe. Similar numbers of PAH compounds and concentrations were found in Lake Tahoe before and after the ban of carbureted two-stroke engines.
Use of Transparency Tubes for Rapid Assessment of Total Suspended Solids and Turbidity in StreamsPaul Anderson; Robert D. DavieLake and Reservoir Management1040-23810743-81412022004 110 - 120Use of Transparency Tubes for Rapid Assessment of Total Suspended Solids and Turbidity in Streams Authors: Paul Andersona; Robert D. Daviea Abstract Studies were conducted to evaluate the use of transparency tubes to predict total suspended solids concentrations (TSS) and NTU turbidity in streams. Linear regression of data collected from 29 sample stations (12 streams) in northeast Ohio revealed a highly predictive correlation for both parameters using the Ohio Sediment Sticko. Laboratory studies showed significant differences between water clarity readings among individual observers using the Ohio Sediment Sticko. The type of visual end point target used in the tube had no effect on water clarity readings. A table to predict TSS concentrations based upon water clarity was developed for the Ohio Sediment Sticko. A comparison of three tubes of differing design (e.g., Minnesota Pollution Control Agency tube, NOAA GLOBE tube, and Ohio Sediment Sticko) found no significant differences in the relationship of water clarity measurement vs. TSS concentrations or NTU turbidity among tubes. Our data indicate that predictive equations developed for the Ohio Sediment Sticko can be applied with statistical confidence to both the MPCA tube and the NOAA GLOBE tube. When appropriately used, transparency tubes can be an effective and inexpensive monitoring tool to estimate relative sediment loads to lakes from different watersheds. Keywords: transparency tube; NTU turbidity; non-point pollution; total suspended solids; volunteer monitoring; streams; Ohio Sediment Sticko; MPCA tube; NOAA GLOBE tube View Full Text ArticleSubscribe Affiliation: a Division of Surface Water, Ohio Environmental Protection Agency, Twinsburg, OH DOI: 10.1080/07438140409354355 Published in: Lake and Reservoir Management, Volume 20, Issue 2 June 2004 , pages 110 - 120 Publication Frequency: 4 issues per year First Published on: 01 June 2004 Formats available: PDF (English) Studies were conducted to evaluate the use of transparency tubes to predict total suspended solids concentrations (TSS) and NTU turbidity in streams. Linear regression of data collected from 29 sample stations (12 streams) in northeast Ohio revealed a highly predictive correlation for both parameters using the Ohio Sediment Sticko. Laboratory studies showed significant differences between water clarity readings among individual observers using the Ohio Sediment Sticko. The type of visual end point target used in the tube had no effect on water clarity readings. A table to predict TSS concentrations based upon water clarity was developed for the Ohio Sediment Sticko. A comparison of three tubes of differing design (e.g., Minnesota Pollution Control Agency tube, NOAA GLOBE tube, and Ohio Sediment Sticko) found no significant differences in the relationship of water clarity measurement vs. TSS concentrations or NTU turbidity among tubes. Our data indicate that predictive equations developed for the Ohio Sediment Sticko can be applied with statistical confidence to both the MPCA tube and the NOAA GLOBE tube. When appropriately used, transparency tubes can be an effective and inexpensive monitoring tool to estimate relative sediment loads to lakes from different watersheds.
Effects of Water Level Fluctuation and Short-Term Climate Variation on Thermal and Stratification Regimes of a British Columbia Reservoir and LakeWeston H. Nowlin; John-Mark Davies; Rick N. Nordin; Asit MazumderLake and Reservoir Management1040-23810743-81412022004 91 - 109Effects of Water Level Fluctuation and Short-Term Climate Variation on Thermal and Stratification Regimes of a British Columbia Reservoir and Lake Authors: Weston H. Nowlina; John-Mark Daviesa; Rick N. Nordina; Asit Mazumdera Abstract Stratification and thermal regimes of a reservoir with fluctuating water levels were compared to a natural lake of similar morphometry and trophic status over a two-year period (2000-2001) in coastal British Columbia, Canada. We compared the timing and duration of stratification, summer heat budgets and heat fluxes in two morphometrically contrasting basins of Sooke Lake Reservoir and Shawnigan Lake (one shallow and one deep basin per water body). In the second year of the study, a 100-year drought allowed us to compare responses of a reservoir and a lake to contrasting years of climatic conditions. Loss of volume from the reservoir during summer and fall caused stratification and thermal regimes to differ from Shawnigan Lake, but the magnitude of these differences was mediated by basin morphometry. Duration of summer stratification, timing of heat content, and the relative importance of seasonal heat fluxes in the shallow basin of Sooke Lake Reservoir were most different from Shawnigan Lake. While there were no major differences between years for Shawnigan Lake, contrasting years in precipitation and hydrology caused Sooke Lake Reservoir stratification and thermal regimes to differ between years. The magnitude of differences between years was mediated by basin size, with the shallower reservoir basin having greater differences between years. Our results indicate that reservoir physical processes are sensitive to short-term changes in hydrology, and that the combined impacts of short-term climate variation and anthropogenic manipulation of hydrology may be greater in shallow reservoir ecosystems. Keywords: reservoir limnology; drawdown; heat budget; climate variability; stratification; thermal regimes; mixing regimes View Full Text ArticleSubscribe Affiliation: a Centre for Water and Watershed Research, Department of Biology, University of Victoria, Victoria, British Columbia, Canada DOI: 10.1080/07438140409354354 Published in: Lake and Reservoir Management, Volume 20, Issue 2 June 2004 , pages 91 - 109 Publication Frequency: 4 issues per year First Published on: 01 June 2004 Formats available: PDF (English) Stratification and thermal regimes of a reservoir with fluctuating water levels were compared to a natural lake of similar morphometry and trophic status over a two-year period (2000-2001) in coastal British Columbia, Canada. We compared the timing and duration of stratification, summer heat budgets and heat fluxes in two morphometrically contrasting basins of Sooke Lake Reservoir and Shawnigan Lake (one shallow and one deep basin per water body). In the second year of the study, a 100-year drought allowed us to compare responses of a reservoir and a lake to contrasting years of climatic conditions. Loss of volume from the reservoir during summer and fall caused stratification and thermal regimes to differ from Shawnigan Lake, but the magnitude of these differences was mediated by basin morphometry. Duration of summer stratification, timing of heat content, and the relative importance of seasonal heat fluxes in the shallow basin of Sooke Lake Reservoir were most different from Shawnigan Lake. While there were no major differences between years for Shawnigan Lake, contrasting years in precipitation and hydrology caused Sooke Lake Reservoir stratification and thermal regimes to differ between years. The magnitude of differences between years was mediated by basin size, with the shallower reservoir basin having greater differences between years. Our results indicate that reservoir physical processes are sensitive to short-term changes in hydrology, and that the combined impacts of short-term climate variation and anthropogenic manipulation of hydrology may be greater in shallow reservoir ecosystems.
Temporal and Vertical Variability in the Relationship Among Organic Matter Indices in a Deep Reservoir EcosystemKwangsoon Choi; Bomchul Kim; Ju-Hyun Park; Yoon-Hee Kim; Mansig JunLake and Reservoir Management1040-23810743-81412022004 130 - 140Temporal and Vertical Variability in the Relationship Among Organic Matter Indices in a Deep Reservoir Ecosystem Authors: Kwangsoon Choia; Bomchul Kima; Ju-Hyun Parka; Yoon-Hee Kima; Mansig Juna Abstract Temporal and vertical variability in the relationship between biochemical oxygen demand (BOD), chemical oxygen demand (CODMn), and total organic carbon (TOC) were investigated in a deep reservoir (Lake Soyang, Korea) and compared with other major reservoirs in Korea. The average oxidation efficiencies of BOD and COD were low (16% and 36%, respectively), compared with TOC analysis. Weakly positive correlations could be observed between TOC vs. BOD (r = 0.64) and TOC vs. CODMn (r = 0.66) in the upper layer, whereas significant correlations were not observed in the middle and deep layers of the water column. In the upper layer, CODMn was more strongly correlated with particulate organic carbon (POC) than with dissolved organic carbon (DOC), even though DOC is ten times more abundant than POC. This might imply that DOC in the lake is more resistant to permanganate oxidation than POC. The oxidation efficiency of BOD, an indicator of biodegradability, varied among water layers (upper > deep > middle layer). The lower efficiency in the middle layer may be due to an input of recalcitrant allochthonous organic matter during the summer monsoon, when water is known to flow into this layer of the lake. The oxidation efficiency of CODMn also varied significantly by water layer (upper ≅ middle > deep layer). Because of poor and variable oxidation efficiencies, BOD and CODMn measured at any particular time or location should be used with caution as indices of organic matter content in lakes. Keywords: BOD; COD; TOC; oxidation efficiency; variation View Full Text ArticleSubscribe Affiliation: a Department of Environmental Science, Kangwon National University, Chunchon, South Korea DOI: 10.1080/07438140409354357 Published in: Lake and Reservoir Management, Volume 20, Issue 2 June 2004 , pages 130 - 140 Publication Frequency: 4 issues per year First Published on: 01 June 2004 Formats available: PDF (English) Temporal and vertical variability in the relationship between biochemical oxygen demand (BOD), chemical oxygen demand (CODMn), and total organic carbon (TOC) were investigated in a deep reservoir (Lake Soyang, Korea) and compared with other major reservoirs in Korea. The average oxidation efficiencies of BOD and COD were low (16% and 36%, respectively), compared with TOC analysis. Weakly positive correlations could be observed between TOC vs. BOD (r = 0.64) and TOC vs. CODMn (r = 0.66) in the upper layer, whereas significant correlations were not observed in the middle and deep layers of the water column. In the upper layer, CODMn was more strongly correlated with particulate organic carbon (POC) than with dissolved organic carbon (DOC), even though DOC is ten times more abundant than POC. This might imply that DOC in the lake is more resistant to permanganate oxidation than POC. The oxidation efficiency of BOD, an indicator of biodegradability, varied among water layers (upper > deep > middle layer). The lower efficiency in the middle layer may be due to an input of recalcitrant allochthonous organic matter during the summer monsoon, when water is known to flow into this layer of the lake. The oxidation efficiency of CODMn also varied significantly by water layer (upper ≅ middle > deep layer). Because of poor and variable oxidation efficiencies, BOD and CODMn measured at any particular time or location should be used with caution as indices of organic matter content in lakes.
Augmentation of a Long-term Monitoring Program for Lake George, NY by Citizen VolunteersCharles W. Boylen; Eric A. Howe; Jeffrey S. Bartkowski; Lawrence W. EichlerLake and Reservoir Management1040-23810743-81412022004 121 - 129Augmentation of a Long-term Monitoring Program for Lake George, NY by Citizen Volunteers Authors: Charles W. Boylena; Eric A. Howea; Jeffrey S. Bartkowskia; Lawrence W. Eichlera Abstract Drinking water standards and recreational demands on lakes and ponded waters place a high priority on the management of water quality. As stakeholders, volunteer citizen monitors can provide considerable assistance to state agencies and research organizations charged with monitoring freshwater resources by accumulating valuable data for water quality evaluation and lake assessment. The Lay Monitoring Program on Lake George (NY) was initiated in 1980 concomitant with the establishment of a long-term chemical monitoring program. By 2002, 23 years of Secchi transparency and surface temperature data had been collected. Results have revealed potential relationships between variations in Secchi transparency and trophic indicators (chlorophyll a and total phosphorus) and have assisted in evaluating the potential influences of both increased recreational use and precipitation regime. Lay monitor participation provides a valuable and cost effective enhancement for ongoing lake chemical and biotic effect studies. The integration of lay monitor Secchi data improves the breadth and consistency of long-term datasets, thereby increasing the program effectiveness in detecting incremental changes in water quality. Keywords: volunteer; lay monitoring; Lake George; New York; Secchi; long-term lake monitoring View Full Text ArticleSubscribe Affiliation: a Darrin Fresh Water Institute, Rensselaer Polytechnic Institute, Bolton Landing, NY DOI: 10.1080/07438140409354356 Published in: Lake and Reservoir Management, Volume 20, Issue 2 June 2004 , pages 121 - 129 Publication Frequency: 4 issues per year First Published on: 01 June 2004 Formats available: PDF (English) Drinking water standards and recreational demands on lakes and ponded waters place a high priority on the management of water quality. As stakeholders, volunteer citizen monitors can provide considerable assistance to state agencies and research organizations charged with monitoring freshwater resources by accumulating valuable data for water quality evaluation and lake assessment. The Lay Monitoring Program on Lake George (NY) was initiated in 1980 concomitant with the establishment of a long-term chemical monitoring program. By 2002, 23 years of Secchi transparency and surface temperature data had been collected. Results have revealed potential relationships between variations in Secchi transparency and trophic indicators (chlorophyll a and total phosphorus) and have assisted in evaluating the potential influences of both increased recreational use and precipitation regime. Lay monitor participation provides a valuable and cost effective enhancement for ongoing lake chemical and biotic effect studies. The integration of lay monitor Secchi data improves the breadth and consistency of long-term datasets, thereby increasing the program effectiveness in detecting incremental changes in water quality.
Spatial Distribution and Seasonal Dynamics of Plankton in a Terminal Multiple-Series ReservoirJohn E. Havel; Kristen R. PattinsonLake and Reservoir Management1040-23810743-81412012004 14 - 26Spatial Distribution and Seasonal Dynamics of Plankton in a Terminal Multiple-Series Reservoir Authors: John E. Havela; Kristen R. Pattinsona Abstract Despite several decades of research on eutrophication in lakes, changes in reservoir plankton communities are poorly understood. The current study examined spatial patterns and dynamics of algae and zooplankton in an oligo-mesotrophic main-stem reservoir, Bull Shoals Lake, Missouri-Arkansas, which is currently threatened from rapid development in upstream reservoirs. Eighteen sites were sampled during one week in summer and the seasonal dynamics of algae and zooplankton were followed at two of these sites. The lake showed strong spatial patterning in transparency, concentrations of phosphorus and chlorophyll-a, and densities of algae and zooplankton. Algal composition also varied substantially among sites, with cyanobacteria most abundant in up-reservoir and tributary sites. Although cyanobacteria were most abundant in late summer, appreciable densities were found throughout the year. Zooplankton were dominated by rotifers and cladocerans, which showed large oscillations in density over time. Abundance peaks occurred earlier in an up-reservoir than in a down-reservoir site, with a time delay of about a month for algae and four months for zooplankton. The plankton composition was consistent with the oligo-mesotrophic status of Bull Shoals Lake, but high densities of cyanobacteria at some tributary sites and in upstream reservoirs indicate localized enrichment and the threat of eutrophication in this clear Ozark lake. Keywords: Bull Shoals Lake; cyanobacteria; Daphnia; trophic interactions; zooplankton View Full Text ArticleSubscribe Affiliation: a Department of Biology, Southwest Missouri State University, Springfield, MO, USA DOI: 10.1080/07438140409354097 Published in: Lake and Reservoir Management Publication Frequency: 4 issues per year First Published on: 01 March 2004 Formats available: PDF (English) Despite several decades of research on eutrophication in lakes, changes in reservoir plankton communities are poorly understood. The current study examined spatial patterns and dynamics of algae and zooplankton in an oligo-mesotrophic main-stem reservoir, Bull Shoals Lake, Missouri-Arkansas, which is currently threatened from rapid development in upstream reservoirs. Eighteen sites were sampled during one week in summer and the seasonal dynamics of algae and zooplankton were followed at two of these sites. The lake showed strong spatial patterning in transparency, concentrations of phosphorus and chlorophyll-a, and densities of algae and zooplankton. Algal composition also varied substantially among sites, with cyanobacteria most abundant in up-reservoir and tributary sites. Although cyanobacteria were most abundant in late summer, appreciable densities were found throughout the year. Zooplankton were dominated by rotifers and cladocerans, which showed large oscillations in density over time. Abundance peaks occurred earlier in an up-reservoir than in a down-reservoir site, with a time delay of about a month for algae and four months for zooplankton. The plankton composition was consistent with the oligo-mesotrophic status of Bull Shoals Lake, but high densities of cyanobacteria at some tributary sites and in upstream reservoirs indicate localized enrichment and the threat of eutrophication in this clear Ozark lake.
Influence of Water Level on Torpedograss Establishment in Lake Okeechobee, FloridaDian H. Smith; R. Michael Smart; Charles G. HanlonLake and Reservoir Management1040-23810743-81412012004 1 - 13Influence of Water Level on Torpedograss Establishment in Lake Okeechobee, Florida Authors: Dian H. Smitha; R. Michael Smarta; Charles G. Hanlonb Abstract Lake Okeechobee, a 173,200 ha shallow subtropical lake located in south Florida, has been invaded recently by torpedograss (Panicum repens), an exotic, terrestrial species, that was intentionally introduced to Florida in the early 1900s. Since the 1970s, more than 6,000 ha of native plants, including spikerush (Eleocharis cellulose) and beakrush (Rhynchospora spp.) and open water habitat have been displaced by torpedograss in areas of the marsh where inundation depths often are less than 50 cm. The ability of torpedograss to disperse and become established at different water depths was evaluated in a series of experimental pond studies. These studies revealed that fragments remain buoyant for extended periods and so facilitate the dispersal of torpedograss within the lake. If fragments become anchored to sediment that is either exposed or in shallow water, they can readily root and establish mature plants. Once established, torpedograss can thrive in depths of 75 cm or less and can survive prolonged exposure to flooding depths greater than 1 m. In this manner, low water periods can contribute to the dispersal and colonization pattern of torpedograss in the lake. When coupled with lake elevation data, these findings suggest that low water levels or drawdowns would increase the marsh area susceptible to torpedograss invasion. Keywords: Panicum repens; torpedograss; stem fragment; rhizome; invasive species; Eleocharis cellulosa; Lake Okeechobee; hydrological effects; invasion View Full Text ArticleSubscribe Affiliations: a USAERDC Lewisville Aquatic Ecosystem Research Facility, Lewisville, Texas b Okeechobee Research Department, South Florida Water Management District, West Palm Beach, Florida DOI: 10.1080/07438140409354096 Published in: Lake and Reservoir Management, Volume 20, Issue 1 March 2004 , pages 1 - 13 Publication Frequency: 4 issues per year First Published on: 01 March 2004 Formats available: PDF (English) Lake Okeechobee, a 173,200 ha shallow subtropical lake located in south Florida, has been invaded recently by torpedograss (Panicum repens), an exotic, terrestrial species, that was intentionally introduced to Florida in the early 1900s. Since the 1970s, more than 6,000 ha of native plants, including spikerush (Eleocharis cellulose) and beakrush (Rhynchospora spp.) and open water habitat have been displaced by torpedograss in areas of the marsh where inundation depths often are less than 50 cm. The ability of torpedograss to disperse and become established at different water depths was evaluated in a series of experimental pond studies. These studies revealed that fragments remain buoyant for extended periods and so facilitate the dispersal of torpedograss within the lake. If fragments become anchored to sediment that is either exposed or in shallow water, they can readily root and establish mature plants. Once established, torpedograss can thrive in depths of 75 cm or less and can survive prolonged exposure to flooding depths greater than 1 m. In this manner, low water periods can contribute to the dispersal and colonization pattern of torpedograss in the lake. When coupled with lake elevation data, these findings suggest that low water levels or drawdowns would increase the marsh area susceptible to torpedograss invasion.
Management Issues, Characteristics and Effectiveness of Lake Associations and Lake Districts in WisconsinAnthony O. Gabriel; Cynthia LancasterLake and Reservoir Management1040-23810743-81412012004 27 - 38Management Issues, Characteristics and Effectiveness of Lake Associations and Lake Districts in Wisconsin Authors: Anthony O. Gabriela; Cynthia Lancasterb Abstract Through a state-wide survey, this paper compares the characteristics of lake associations and lake districts, including their management objectives, issues, activities, and use of funds and contacts. It also examines the relationships between reported management activities and effectiveness and the nature of the issues, lake characteristics, and organizational characteristics. Lake associations and districts have distinct goals and significant differences in the lake issues each finds important, their activities, and effectiveness. Overall, lake districts tend to initiate higher numbers of actions on important issues, while lake associations tend to report a significantly higher proportion of management actions effectively addressing those issues. Lake associations and districts also differ greatly in their sources of revenue and expenditures, with lake districts having significantly higher amounts in both. We found a positive correlation between the total number of lake management activities undertaken by lake management organizations and the number of cottages, percentage of permanent residents, and property values found on their lake, as well as their membership sizes and annual membership fees. The number of cottages and membership sizes were also significantly correlated with the number of management activities initiated, while the number of cottages was the only factor significantly correlated with the number of issues effectively addressed. We found that organizations affiliated with Wisconsin Association of Lakes are engaged insignificantly higher number of activities and effective solutions. In addition, significantly higher numbers of activities are undertaken by lake districts, as well as organizations that are incorporated and have written by-laws. Keywords: lake management; lake associations; lake districts; Wisconsin View Full Text ArticleSubscribe Affiliations: a Department of Geography and Land Studies, Central Washington University, Ellensburg, WA b Wisconsin Department of Natural Resources, Oshkosh, WI DOI: 10.1080/07438140409354098 Published in: Lake and Reservoir Management, Volume 20, Issue 1 March 2004 , pages 27 - 38 Publication Frequency: 4 issues per year First Published on: 01 March 2004 Formats available: PDF (English) Through a state-wide survey, this paper compares the characteristics of lake associations and lake districts, including their management objectives, issues, activities, and use of funds and contacts. It also examines the relationships between reported management activities and effectiveness and the nature of the issues, lake characteristics, and organizational characteristics. Lake associations and districts have distinct goals and significant differences in the lake issues each finds important, their activities, and effectiveness. Overall, lake districts tend to initiate higher numbers of actions on important issues, while lake associations tend to report a significantly higher proportion of management actions effectively addressing those issues. Lake associations and districts also differ greatly in their sources of revenue and expenditures, with lake districts having significantly higher amounts in both. We found a positive correlation between the total number of lake management activities undertaken by lake management organizations and the number of cottages, percentage of permanent residents, and property values found on their lake, as well as their membership sizes and annual membership fees. The number of cottages and membership sizes were also significantly correlated with the number of management activities initiated, while the number of cottages was the only factor significantly correlated with the number of issues effectively addressed. We found that organizations affiliated with Wisconsin Association of Lakes are engaged insignificantly higher number of activities and effective solutions. In addition, significantly higher numbers of activities are undertaken by lake districts, as well as organizations that are incorporated and have written by-laws.
Improvement in Moses Lake Quality from Dilution and Sewage DiversionEugene B. Welch; Evan R. WeiherLake and Reservoir Management1040-23810743-81412012004 76 - 84Improvement in Moses Lake Quality from Dilution and Sewage Diversion Authors: Eugene B. Welcha; Evan R. Weihera Abstract Moses Lake has received dilution water in 9 of 10 years since treatment began in 1977. The average input for those years was 143 79 106 m3/yr over 93 days, which represents flushing rates of about 13 percent/day for Parker Horn where the dilution water enters, and 1 percent/day for the whole lake. As a result, lake quality has improved at least 50 percent in terms of chlorophyll a and total phosphorus and by nearly 100 percent in transparency. Pumping diluted lake water from Parker Horn beginning in 1982 and diverting sewage effluent in 1984 markedly improved water quality in a section that received treated effluent and little or no dilution water. Total phosphorus has declined by 90 percent and chlorophyll a by 60 percent, although transparency increased only about 0.2 m because of that section's shallowness. Diluted nitrate concentration in the inflow has been considered the cause for control of algae, but a switch from largely flood to spray irrigation, as well as sewage diversion, has resulted in lower inflow phosphorus concentrations and a gradual change from N to P limitation. Despite favorable improvements in average conditions, however, blooms of blue-green algae still develop in late summer. The largest bloom in the 10 + year study occurred from late August through September 1985, when the lake was well diluted and received no sewage. This is attributed to increased mixing following lower than normal temperature and to a 50 percent increase in internal phosphorus loading. Buoyant bluegreen algae rising from the sediment surface are hypothesized to be the transport mechanism. Keywords: Moses Lake; Washington; water quality; nutrient enrichment; algae; chlorophyll a; nitrogen; phosphorus; sewage effluent View Full Text ArticleSubscribe Affiliation: a Department of Civil Engineering, University of Washington Seattle, Washington DOI: 10.1080/07438140409354102 Published in: Lake and Reservoir Management, Volume 20, Issue 1 March 2004 , pages 76 - 84 Publication Frequency: 4 issues per year First Published on: 01 March 2004 Formats available: PDF (English) Moses Lake has received dilution water in 9 of 10 years since treatment began in 1977. The average input for those years was 143 79 106 m3/yr over 93 days, which represents flushing rates of about 13 percent/day for Parker Horn where the dilution water enters, and 1 percent/day for the whole lake. As a result, lake quality has improved at least 50 percent in terms of chlorophyll a and total phosphorus and by nearly 100 percent in transparency. Pumping diluted lake water from Parker Horn beginning in 1982 and diverting sewage effluent in 1984 markedly improved water quality in a section that received treated effluent and little or no dilution water. Total phosphorus has declined by 90 percent and chlorophyll a by 60 percent, although transparency increased only about 0.2 m because of that section's shallowness. Diluted nitrate concentration in the inflow has been considered the cause for control of algae, but a switch from largely flood to spray irrigation, as well as sewage diversion, has resulted in lower inflow phosphorus concentrations and a gradual change from N to P limitation. Despite favorable improvements in average conditions, however, blooms of blue-green algae still develop in late summer. The largest bloom in the 10 + year study occurred from late August through September 1985, when the lake was well diluted and received no sewage. This is attributed to increased mixing following lower than normal temperature and to a 50 percent increase in internal phosphorus loading. Buoyant bluegreen algae rising from the sediment surface are hypothesized to be the transport mechanism.
Book ReviewJames F. LaBountyLake and Reservoir Management1040-23810743-8141201200485Book Review Author: James F. LaBountya View Full Text ArticleSubscribe Affiliation: a Aquatic Scientist, Castle Rock, CO DOI: 10.1080/07438140409354103 Published in: Lake and Reservoir Management, Volume 20, Issue 1 March 2004 , page 85 Publication Frequency: 4 issues per year First Published on: 01 March 2004 Formats available: PDF (English)
Changes in the Plant and Fish Communities in Enhanced Littoral Areas of Lake Kissimmee, Florida, Following a Habitat EnhancementKimberly I. Tugend; Micheal S. AllenLake and Reservoir Management1040-23810743-81412012004 54 - 64Changes in the Plant and Fish Communities in Enhanced Littoral Areas of Lake Kissimmee, Florida, Following a Habitat Enhancement Authors: Kimberly I. Tugenda; Micheal S. Allena Abstract A 1995-96 habitat enhancement project was conducted at Lake Kissimmee, Florida, which included a major drawdown and organic sediment removal from about half of the lake's shoreline. Previous studies have compared enhanced versus control sites following habitat enhancements, but no studies have assessed how plant and fish communities change through time in enhanced habitats. We sampled plant and fish communities in two enhanced littoral areas three times each summer from 1998 to 2000. Quality fish habitat (i.e., sandy bottom, moderate coverage of aquatic macrophytes, high dissolved oxygen concentrations) was present in enhanced sites throughout this study. Irrespective of water level, plant abundance (percent area covered, PAC) and biomass increased during the study period, but mean plant biomass and abundance were < 2 kg · m-2 and < 50%, respectively, in 2000. Mean dissolved oxygen concentrations in enhanced sites generally exceeded 3 mg · L-1 in all years. Diverse fish communities also reflected quality habitat in enhanced sites. No fish variables differed between sites, but fish diversity and richness were highest during 1999 when water levels were high. Mean water depth and PAC, when significant, were positively related to fish variables (e.g., biomass, diversity). The results of this study suggest that the benefits of the 1995-96 Lake Kissimmee habitat enhancement were prolonged compared to a previous effort, which may be due, in part, to herbicide treatments. Keywords: drawdown; aquatic; macrophytes; fish community dynamics View Full Text ArticleSubscribe Affiliation: a Department of Fisheries and Aquatic Sciences, The University of Florida, Gainesville, FL DOI: 10.1080/07438140409354100 Published in: Lake and Reservoir Management, Volume 20, Issue 1 March 2004 , pages 54 - 64 Publication Frequency: 4 issues per year First Published on: 01 March 2004 Formats available: PDF (English) A 1995-96 habitat enhancement project was conducted at Lake Kissimmee, Florida, which included a major drawdown and organic sediment removal from about half of the lake's shoreline. Previous studies have compared enhanced versus control sites following habitat enhancements, but no studies have assessed how plant and fish communities change through time in enhanced habitats. We sampled plant and fish communities in two enhanced littoral areas three times each summer from 1998 to 2000. Quality fish habitat (i.e., sandy bottom, moderate coverage of aquatic macrophytes, high dissolved oxygen concentrations) was present in enhanced sites throughout this study. Irrespective of water level, plant abundance (percent area covered, PAC) and biomass increased during the study period, but mean plant biomass and abundance were < 2 kg · m-2 and < 50%, respectively, in 2000. Mean dissolved oxygen concentrations in enhanced sites generally exceeded 3 mg · L-1 in all years. Diverse fish communities also reflected quality habitat in enhanced sites. No fish variables differed between sites, but fish diversity and richness were highest during 1999 when water levels were high. Mean water depth and PAC, when significant, were positively related to fish variables (e.g., biomass, diversity). The results of this study suggest that the benefits of the 1995-96 Lake Kissimmee habitat enhancement were prolonged compared to a previous effort, which may be due, in part, to herbicide treatments.
Assessing Iron Dynamics in the Release from a Stratified ReservoirSteven L. Ashby; Stephen P. Faulkner; Robert P. Gambrell; Brenda A. SmithLake and Reservoir Management1040-23810743-81412012004 65 - 75Assessing Iron Dynamics in the Release from a Stratified Reservoir Authors: Steven L. Ashbya; Stephen P. Faulknerb; Robert P. Gambrellc; Brenda A. Smithd Abstract Field and laboratory studies were conducted to describe the fate of total, dissolved, and ferrous (Fe2+) iron in the release from a stratified reservoir with an anoxic hypolimnion. Concentrations of total iron in the tailwater indicated a first order removal process during a low flow release (0.6 m3 sec-1), yet negligible loss was observed during a period of increased discharge (2.8 m3 sec-1). Dissolved and ferrous iron concentrations in the tailwater were highly variable during both release regimes and did not follow responses based on theoretical predictions. Ferrous iron concentrations in unfiltered samples were consistently greater than concentrations observed in samples filtered separately through 0.4, 0.2, and 0.1 μm filters. Total iron removal in laboratory studies followed first order kinetics, but was twice that rate (0.077 mg L-1 hr-1) observed during low flow discharge in the tailwater (0.036 mg L-1 hr-1). Dissolved and ferrous iron losses in laboratory studies were rapid (~75% in the first 15 minutes and 95% within 1 hour), followed theoretical predictions, and were much faster than observations in the tailwater (~30% within the first hour). The presence of particulate forms of ferrous iron in the field and differences in removal rates observed in field and laboratory studies indicate a need for improved field assessment techniques and consideration of complexation reactions when assessing the dynamics of iron in reservoir releases and downstream impacts as a result of operation regimes. Keywords: iron; ferrous; ferric; tailwaters; reservoirs; water quality View Full Text ArticleSubscribe Affiliations: a Environmental Laboratory, U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS b U.S. Geological Survey, Lafayette, LA c Louisiana State University, Wetland Biogeochemistry Institute, Baton Rouge, LA d Texas Commission on Environmental Quality, Austin, TX DOI: 10.1080/07438140409354101 Published in: Lake and Reservoir Management, Volume 20, Issue 1 March 2004 , pages 65 - 75 Publication Frequency: 4 issues per year First Published on: 01 March 2004 Formats available: PDF (English) Field and laboratory studies were conducted to describe the fate of total, dissolved, and ferrous (Fe2+) iron in the release from a stratified reservoir with an anoxic hypolimnion. Concentrations of total iron in the tailwater indicated a first order removal process during a low flow release (0.6 m3 sec-1), yet negligible loss was observed during a period of increased discharge (2.8 m3 sec-1). Dissolved and ferrous iron concentrations in the tailwater were highly variable during both release regimes and did not follow responses based on theoretical predictions. Ferrous iron concentrations in unfiltered samples were consistently greater than concentrations observed in samples filtered separately through 0.4, 0.2, and 0.1 μm filters. Total iron removal in laboratory studies followed first order kinetics, but was twice that rate (0.077 mg L-1 hr-1) observed during low flow discharge in the tailwater (0.036 mg L-1 hr-1). Dissolved and ferrous iron losses in laboratory studies were rapid (~75% in the first 15 minutes and 95% within 1 hour), followed theoretical predictions, and were much faster than observations in the tailwater (~30% within the first hour). The presence of particulate forms of ferrous iron in the field and differences in removal rates observed in field and laboratory studies indicate a need for improved field assessment techniques and consideration of complexation reactions when assessing the dynamics of iron in reservoir releases and downstream impacts as a result of operation regimes.
Operation and Evaluation of Hypolimnetic Withdrawal in a Shallow Eutrophic LakeRonald H. Macdonald; Gregory A. Lawrence; Thomas P. MurphyLake and Reservoir Management1040-23810743-81412012004 39 - 53Operation and Evaluation of Hypolimnetic Withdrawal in a Shallow Eutrophic Lake Authors: Ronald H. Macdonalda; Gregory A. Lawrencea; Thomas P. Murphyb Abstract Chain Lake is a small (46 ha), shallow (zmean = 6 m, zmax = 9 m) eutrophic lake in the interior of British Columbia, Canada. It suffers from severe blue-green algae blooms fed by internally loaded phosphorus. A hypolimnetic withdrawal system began operation in 1994, and is operated annually during the ice free period of the year. It is gravity driven (no mechanical pumps) and can operate at rates up to 80 L · s-1. A monitoring program implemented as part of the withdrawal installation evaluated total phosphorus export, lake water quality effects, and downstream environmental impacts. The withdrawal does not accelerate hydraulic flushing of the lake (residence time 0.5-3 years) but preferentially drains the water column below 5 m every 100 days and drains the deepest region of the lake (6-9 m) approximately every two weeks. Total phosphorus export in the first year of operation was 30 kg, and optimization of the operation strategy should increase export to 60 kg per year, resulting in a net export of total phosphorus from the lake. Long term monitoring of water quality has been performed by resident volunteers for nine years (1994 - 2002) using Secchi measurements. Only a few data are available prior to the withdrawal operation. A non-parametric trend test found statistically significant increases of the monthly median Secchi depth for June (p<0.05) and August (p<0.10). Optimization of the withdrawal operation to maximize phosphorus export can be done by earlier start-up after ice off and increasing flow rates during the most anoxic periods. Downstream concerns with respect to the withdrawal operation include: dissolved oxygen depletion observed at the withdrawal site and up to 500 m downstream; nutrient enrichment with elevated concentrations of phosphorus observed in the withdrawn water; and elevated levels of ammonia, iron, and manganese observed in the withdrawn water in the first year of monitoring. The effects of anoxic water discharge were partially mitigated by a fountain aerator at the discharge point which increased the dissolved oxygen in the withdrawal stream by up to 2.0 mg · L-1. Keywords: lake restoration; hypolimnetic withdrawal; internal loading; phosphorus; shallow lake View Full Text ArticleSubscribe Affiliations: a Department of Civil Engineering, University of British Columbia, Vancouver, B.C., Canada b National Water Research Institute Environment Canada, Burlington, Ontario, Canada DOI: 10.1080/07438140409354099 Published in: Lake and Reservoir Management, Volume 20, Issue 1 March 2004 , pages 39 - 53 Publication Frequency: 4 issues per year First Published on: 01 March 2004 Formats available: PDF (English) Chain Lake is a small (46 ha), shallow (zmean = 6 m, zmax = 9 m) eutrophic lake in the interior of British Columbia, Canada. It suffers from severe blue-green algae blooms fed by internally loaded phosphorus. A hypolimnetic withdrawal system began operation in 1994, and is operated annually during the ice free period of the year. It is gravity driven (no mechanical pumps) and can operate at rates up to 80 L · s-1. A monitoring program implemented as part of the withdrawal installation evaluated total phosphorus export, lake water quality effects, and downstream environmental impacts. The withdrawal does not accelerate hydraulic flushing of the lake (residence time 0.5-3 years) but preferentially drains the water column below 5 m every 100 days and drains the deepest region of the lake (6-9 m) approximately every two weeks. Total phosphorus export in the first year of operation was 30 kg, and optimization of the operation strategy should increase export to 60 kg per year, resulting in a net export of total phosphorus from the lake. Long term monitoring of water quality has been performed by resident volunteers for nine years (1994 - 2002) using Secchi measurements. Only a few data are available prior to the withdrawal operation. A non-parametric trend test found statistically significant increases of the monthly median Secchi depth for June (p<0.05) and August (p<0.10). Optimization of the withdrawal operation to maximize phosphorus export can be done by earlier start-up after ice off and increasing flow rates during the most anoxic periods. Downstream concerns with respect to the withdrawal operation include: dissolved oxygen depletion observed at the withdrawal site and up to 500 m downstream; nutrient enrichment with elevated concentrations of phosphorus observed in the withdrawn water; and elevated levels of ammonia, iron, and manganese observed in the withdrawn water in the first year of monitoring. The effects of anoxic water discharge were partially mitigated by a fountain aerator at the discharge point which increased the dissolved oxygen in the withdrawal stream by up to 2.0 mg · L-1.
An Artificially Induced Planktothrix rubescens Surface Bloom in a Small Kettle Lake in Southern Ontario Compared to Blooms World-wideGertrud K. Nürnberg; Bruce D. LaZerte; Daniel D. OldingLake and Reservoir Management1040-23810743-81411942003307 - 322An Artificially Induced Planktothrix rubescens Surface Bloom in a Small Kettle Lake in Southern Ontario Compared to Blooms World-wide Authors: Gertrud K. Nrnberga; Bruce D. LaZertea; Daniel D. Oldingb Abstract To combat hypolimnetic anoxia and sediment phosphorus release in a small, mesotrophic kettle lake on the Oakridge Moraine north of the Metropolitan Toronto, Southern Ontario, oxygenation and aeration was applied to the hypolimnion alternately during the summer of 1998 until mid-November and then to the entire water column until the end of December. This treatment coincided with the proliferation of a toxic strain of the purple cyanobacterium, Planktothrix rubescens, from almost undetectable values to bloom conditions under ice in the following winter and spring. Although small numbers of P. rubescens have been detected during several years before the treatment, prolonged artificial mixing in the fall and winter of 1998 distributed numerous filaments throughout the water column and to the surface when light was suitably low for these algae to survive and grow. Algae were supported by simultaneous entrainment and mixing of nutrients from the enriched bottom water. Such blooms of P. rubescens and related bluegreens have been found in many lakes with comparable characteristics and during similar episodes like those of the study lake. Lakes were typically stratified, mesotrophic hardwater lakes, with phosphorus levels that have recently been increasing to levels above 20 μg L-1. Blooms occurred during periods of low light and enhanced mixing, in several cases after treating the lake with whole-lake aeration and mixing. Recommendations to prevent such blooms in Lake Wilcox are (1) the discontinuation of artificial mixing during periods of natural destratification in the fall and winter, (2) the prevention of further eutrophication, and (3) the installation of an in-lake treatment, such as hypolimnetic withdrawal, to decrease internal phosphorus loading from anoxic sediment surfaces. Keywords: toxic Planktothrix rubescens blooms; Ontario kettle lake; eutrophication; artificial destratification; hypolimnetic aeration View Full Text ArticleSubscribe Affiliations: a Freshwater Research, Baysville, Ontario, Canada b Town of Richmond Hill, Richmond Hill, Ontario, Canada DOI: 10.1080/07438140309353941 Published in: Lake and Reservoir Management Publication Frequency: 4 issues per year First Published on: 01 December 2003 Formats available: PDF (English) To combat hypolimnetic anoxia and sediment phosphorus release in a small, mesotrophic kettle lake on the Oakridge Moraine north of the Metropolitan Toronto, Southern Ontario, oxygenation and aeration was applied to the hypolimnion alternately during the summer of 1998 until mid-November and then to the entire water column until the end of December. This treatment coincided with the proliferation of a toxic strain of the purple cyanobacterium, Planktothrix rubescens, from almost undetectable values to bloom conditions under ice in the following winter and spring. Although small numbers of P. rubescens have been detected during several years before the treatment, prolonged artificial mixing in the fall and winter of 1998 distributed numerous filaments throughout the water column and to the surface when light was suitably low for these algae to survive and grow. Algae were supported by simultaneous entrainment and mixing of nutrients from the enriched bottom water. Such blooms of P. rubescens and related bluegreens have been found in many lakes with comparable characteristics and during similar episodes like those of the study lake. Lakes were typically stratified, mesotrophic hardwater lakes, with phosphorus levels that have recently been increasing to levels above 20 μg L-1. Blooms occurred during periods of low light and enhanced mixing, in several cases after treating the lake with whole-lake aeration and mixing. Recommendations to prevent such blooms in Lake Wilcox are (1) the discontinuation of artificial mixing during periods of natural destratification in the fall and winter, (2) the prevention of further eutrophication, and (3) the installation of an in-lake treatment, such as hypolimnetic withdrawal, to decrease internal phosphorus loading from anoxic sediment surfaces.
Impacts of a Soda Ash Facility on Onondaga Lake and the Seneca River, NYSteven W. Effler; David A. MatthewsLake and Reservoir Management1040-23810743-81411942003285 - 306Impacts of a Soda Ash Facility on Onondaga Lake and the Seneca River, NY Authors: Steven W. Efflera; David A. Matthewsa Abstract A synthesis of the impacts of the operation (1884-1986) of a soda ash (Na2CO3) manufacturing facility on Onondaga Lake, NY, its tributaries, and adjoining portions of the river that receives the lake's outflow is presented, based on long-term programs of monitoring, process studies, and mathematical modeling. The lake was used as a source of cooling water and for the disposal of ionic (Cl- Na+, and Ca2+) waste, related solids and spent cooling water. At peak production the facility discharged ~1.3 106 metric tons of ionic waste to the lake annually. The soda ash facility had a profound impact on these ecosystems, by severely altering their structure and function. Portions of the two largest tributaries to the lake have been degraded from solids deposition associated with solution mining for NaCl (process reactant) and precipitation of Ca2+ waste (as CaCO3). The cooling water operation recycled phosphorus enriched hypolimnetic waters to the epilimnion. Ionic waste impacts on the lake and river included: (1) high salinity (S~3%o), (2) plunging inflows made dense by high S, that altered fundamental features of the lake's stratification regime and exacerbated the problem of severe dissolved oxygen (DO) depletion, (3) S-based density stratification and severe DO depletion over a 14 km reach of the river downstream of the lake, and (4) high levels of CaCO3 precipitation that reduced clarity, increased net sedimentation in pelagic areas, altered the character of near-shore sediments, and reduced alkalinity and pH. These impacts on the lake's chemistry and physical properties had profound effects on biological communities, including: (1) altered composition, (2) reduced richness and diversity, (3) limited macrophyte occurrence, (4) enhanced phytoplankton production, and (5) limited effectiveness of zooplankton grazing, thereby preventing intervals of high clarity. Closure of the facility resulted in dramatic improvements in water quality and ecological characteristics of these systems. Further improvement is expected as residual ionic waste loads decrease. Keywords: ionic pollution; chloride; sodium; calcium; industry; loads; tributary; stratification View Full Text ArticleSubscribe Affiliation: a Upstate Freshwater Institute, Syracuse, NY DOI: 10.1080/07438140309353940 Published in: Lake and Reservoir Management, Volume 19, Issue 4 December 2003 , pages 285 - 306 Publication Frequency: 4 issues per year First Published on: 01 December 2003 Formats available: PDF (English) A synthesis of the impacts of the operation (1884-1986) of a soda ash (Na2CO3) manufacturing facility on Onondaga Lake, NY, its tributaries, and adjoining portions of the river that receives the lake's outflow is presented, based on long-term programs of monitoring, process studies, and mathematical modeling. The lake was used as a source of cooling water and for the disposal of ionic (Cl- Na+, and Ca2+) waste, related solids and spent cooling water. At peak production the facility discharged ~1.3 106 metric tons of ionic waste to the lake annually. The soda ash facility had a profound impact on these ecosystems, by severely altering their structure and function. Portions of the two largest tributaries to the lake have been degraded from solids deposition associated with solution mining for NaCl (process reactant) and precipitation of Ca2+ waste (as CaCO3). The cooling water operation recycled phosphorus enriched hypolimnetic waters to the epilimnion. Ionic waste impacts on the lake and river included: (1) high salinity (S~3%o), (2) plunging inflows made dense by high S, that altered fundamental features of the lake's stratification regime and exacerbated the problem of severe dissolved oxygen (DO) depletion, (3) S-based density stratification and severe DO depletion over a 14 km reach of the river downstream of the lake, and (4) high levels of CaCO3 precipitation that reduced clarity, increased net sedimentation in pelagic areas, altered the character of near-shore sediments, and reduced alkalinity and pH. These impacts on the lake's chemistry and physical properties had profound effects on biological communities, including: (1) altered composition, (2) reduced richness and diversity, (3) limited macrophyte occurrence, (4) enhanced phytoplankton production, and (5) limited effectiveness of zooplankton grazing, thereby preventing intervals of high clarity. Closure of the facility resulted in dramatic improvements in water quality and ecological characteristics of these systems. Further improvement is expected as residual ionic waste loads decrease.
Optimizing Artificial Aeration for Lake Winterkill PreventionTheron G. Miller; W. C. MackayLake and Reservoir Management1040-23810743-81411942003355 - 363Optimizing Artificial Aeration for Lake Winterkill Prevention Authors: Theron G. Millera; W. C. Mackayb Abstract Optimizing winter lake aeration equipment has never been quantified in situ with regard to air or water flow, polynya size (the open water area created by the aerators), or energy required to maintain adequate dissolved oxygen (DO) concentrations. We conducted experiments using different combinations of compressors, air diffusers and mechanical surface aerators in winterkill lakes in northwest Alberta in order to determine a simplified approach to aeration equipment sizing. A hyperbolic relationship existed between energy use and polynya size. The largest polynya sizes were created using 0.15 kW ha-1 with both submersed air injection and surface aerators. However, adequate DO concentrations were maintained with surface aeration using one-third to one-half of the energy used for air injection. Optimal sizing occurred with 0.15-0.23 kW ha-1 for air injection and 0.06-0.1 kW ha-1 for surface aeration. Keywords: winter lake aeration; winterkill prevention; equipment sizing; energy use; mechanical surface aeration; air injection View Full Text ArticleSubscribe Affiliations: a Utah Department of Environmental, Salt Lake City, Utah b Department of Biological Sciences, University of Alberta, Edmonton, AB DOI: 10.1080/07438140309353945 Published in: Lake and Reservoir Management, Volume 19, Issue 4 December 2003 , pages 355 - 363 Publication Frequency: 4 issues per year First Published on: 01 December 2003 Formats available: PDF (English) Optimizing winter lake aeration equipment has never been quantified in situ with regard to air or water flow, polynya size (the open water area created by the aerators), or energy required to maintain adequate dissolved oxygen (DO) concentrations. We conducted experiments using different combinations of compressors, air diffusers and mechanical surface aerators in winterkill lakes in northwest Alberta in order to determine a simplified approach to aeration equipment sizing. A hyperbolic relationship existed between energy use and polynya size. The largest polynya sizes were created using 0.15 kW ha-1 with both submersed air injection and surface aerators. However, adequate DO concentrations were maintained with surface aeration using one-third to one-half of the energy used for air injection. Optimal sizing occurred with 0.15-0.23 kW ha-1 for air injection and 0.06-0.1 kW ha-1 for surface aeration.
Reconstructing Eutrophication and Phosphorus Loading for Lake Volney, Minnesota: Combining Lake Sediments and Land-Use History to Establish ‘Natural’ Baselines for Management and RestorationCharles E. Umbanhowar Jr.; Daniel R. Engstrom; Eric C. BergmanLake and Reservoir Management1040-23810743-81411942003364 - 372Reconstructing Eutrophication and Phosphorus Loading for Lake Volney, Minnesota: Combining Lake Sediments and Land-Use History to Establish 'Natural' Baselines for Management and Restoration Authors: Charles E. Umbanhowar Jr.a; Daniel R. Engstromb; Eric C. Bergmana Abstract Establishing management targets for lake nutrient inputs remains a major challenge to limnologists and resource managers concerned with the cultural eutrophication of lakes. In this study we used multiple sediment cores to reconstruct pre-Euroamerican (1650-1850) phosphorus (P) loading to Lake Volney, a hypereutrophic lake in Le Sueur County, Minnesota, and compared changes in P inputs to inferred changes in lake productivity based on biogenic silica (bSi). Euroamerican changes in land-use, as abstracted from census and tax records, were also compared with sedimentary proxies for soil erosion - loss-on-ignition and environmental magnetism. Whole-basin P accumulation in Lake Volney ranged from 0.31 - 0.39 g m-2 yr-1 prior to the arrival of Euroamerican agriculture in the 1850s. There-after P accumulation rose nearly three-fold largely due to increased fluxes of organic and non-apatite inorganic P. P inputs were highest (3.9 g m-2 yr-1) when organic, apatite and non-apatite P all peaked. Modern P accumulation rates of 1.3 g m-2 yr-1 match closely P-loading estimates based on monitoring data and mass-balance calculations. Lake productivity showed little change until the early 1900s when bSi accumulation rose 5-10x over pre-1900 values. The initial increase in P loading observed in the 1850s corresponds closely to the arrival of Euroamericans in the Lake Volney watershed. Causes for the second increase in P inputs (1910-1930) seem related to an overall increase in large animal numbers (swine and cattle) that began in the 1910s. The methods combined in this study provide site-specific reconstructions of trophic change and its causes that can be used to guide lake management and restoration. Keywords: eutrophication; Lake Volney; LOI; magnetics; paleolimnology; phosphorus; sediment; watershed View Full Text ArticleSubscribe Affiliations: a Department of Biology, St. Olaf College, Northfield, MN, USA b St. Croix Watershed Research Station Science Museum of Minnesota, Marine on St. Croix, MN, USA DOI: 10.1080/07438140309353946 Published in: Lake and Reservoir Management, Volume 19, Issue 4 December 2003 , pages 364 - 372 Publication Frequency: 4 issues per year First Published on: 01 December 2003 Formats available: PDF (English) Establishing management targets for lake nutrient inputs remains a major challenge to limnologists and resource managers concerned with the cultural eutrophication of lakes. In this study we used multiple sediment cores to reconstruct pre-Euroamerican (1650-1850) phosphorus (P) loading to Lake Volney, a hypereutrophic lake in Le Sueur County, Minnesota, and compared changes in P inputs to inferred changes in lake productivity based on biogenic silica (bSi). Euroamerican changes in land-use, as ed from census and tax records, were also compared with sedimentary proxies for soil erosion - loss-on-ignition and environmental magnetism. Whole-basin P accumulation in Lake Volney ranged from 0.31 - 0.39 g m-2 yr-1 prior to the arrival of Euroamerican agriculture in the 1850s. There-after P accumulation rose nearly three-fold largely due to increased fluxes of organic and non-apatite inorganic P. P inputs were highest (3.9 g m-2 yr-1) when organic, apatite and non-apatite P all peaked. Modern P accumulation rates of 1.3 g m-2 yr-1 match closely P-loading estimates based on monitoring data and mass-balance calculations. Lake productivity showed little change until the early 1900s when bSi accumulation rose 5-10x over pre-1900 values. The initial increase in P loading observed in the 1850s corresponds closely to the arrival of Euroamericans in the Lake Volney watershed. Causes for the second increase in P inputs (1910-1930) seem related to an overall increase in large animal numbers (swine and cattle) that began in the 1910s. The methods combined in this study provide site-specific reconstructions of trophic change and its causes that can be used to guide lake management and restoration.
Evaluation of Beach Grooming Techniques on Escherichia coli Density in Foreshore Sand at North Beach, Racine, WIJulie L. Kinzelman; Richard L. Whitman; Muruleedhara Byappanahalli; Emma Jackson; Robert C. BagleyLake and Reservoir Management1040-23810743-81411942003349 - 354Evaluation of Beach Grooming Techniques on Escherichia coli Density in Foreshore Sand at North Beach, Racine, WI Authors: Julie L. Kinzelmana; Richard L. Whitmanb; Muruleedhara Byappanahallib; Emma Jacksonc; Robert C. Bagleya Abstract Elevated levels of Escherichia coli(E. coli) in bathing waters at North Beach, a popular recreational site in Racine, Wisconsin, have been a persistent problem often resulting in the issuance of poor water quality advisories. Moreover, waterfowl (mostly Larus delawarensis and L. argentatus) in nearshore and offshore areas are common and may serve as non-point sources for bacterial contamination of recreational waters. Current beach management practice involves daily mechanical grooming of the nearshore sand for aesthetics and removal of hazardous debris. However, this practice has not been evaluated in terms of its effects on E. coli loading to beach sand and potential introduction to contiguous swimming water. In this study, we tested E. coli responses to three treatments: mechanical groomer, daily and twice weekly hand raking, and a control (no raking/grooming). A randomized block design consisted of replicated treatments and one control (10 each), for a total of 40 blocks sampled daily for 10 days. Foreshore sand samples were collected by hand coring to an average depth of 10 cm. Median E. coli recovered were 73 (mechanically groomed), 27 (hand-raked daily), 32 (hand-raked twice weekly), and 22 (control) colony-forming units (CFU) per gram dry weight sand. E. coli counts in sand that was groomed were significantly higher than hand rakings and control (p <0.0001), and there was no significant difference between control and raking treatments (p<0.01). This study demonstrates the beach management implications related to grooming efficacy and the importance of understanding non-point sources of bacterial contamination. Keywords: beach grooming; foreshore sand; non-point pollution; water quality; E. coli View Full Text ArticleSubscribe Affiliations: a City of Racine Health Department Laboratory, Racine, WI b USGS Great Lakes Science Center, Porter, IN c University of Surrey, Guildford, Surrey, UK DOI: 10.1080/07438140309353944 Published in: Lake and Reservoir Management, Volume 19, Issue 4 December 2003 , pages 349 - 354 Publication Frequency: 4 issues per year First Published on: 01 December 2003 Formats available: PDF (English) Elevated levels of Escherichia coli(E. coli) in bathing waters at North Beach, a popular recreational site in Racine, Wisconsin, have been a persistent problem often resulting in the issuance of poor water quality advisories. Moreover, waterfowl (mostly Larus delawarensis and L. argentatus) in nearshore and offshore areas are common and may serve as non-point sources for bacterial contamination of recreational waters. Current beach management practice involves daily mechanical grooming of the nearshore sand for aesthetics and removal of hazardous debris. However, this practice has not been evaluated in terms of its effects on E. coli loading to beach sand and potential introduction to contiguous swimming water. In this study, we tested E. coli responses to three treatments: mechanical groomer, daily and twice weekly hand raking, and a control (no raking/grooming). A randomized block design consisted of replicated treatments and one control (10 each), for a total of 40 blocks sampled daily for 10 days. Foreshore sand samples were collected by hand coring to an average depth of 10 cm. Median E. coli recovered were 73 (mechanically groomed), 27 (hand-raked daily), 32 (hand-raked twice weekly), and 22 (control) colony-forming units (CFU) per gram dry weight sand. E. coli counts in sand that was groomed were significantly higher than hand rakings and control (p <0.0001), and there was no significant difference between control and raking treatments (p<0.01). This study demonstrates the beach management implications related to grooming efficacy and the importance of understanding non-point sources of bacterial contamination.
Modeling Phosphorus Dynamics in a Shallow Lake During an Episodic EventXinjian Chen; Y. Peter ShengLake and Reservoir Management1040-23810743-81411942003323 - 340Modeling Phosphorus Dynamics in a Shallow Lake During an Episodic Event Authors: Xinjian Chenab; Y. Peter Shengc Abstract Wind, current, suspended sediment, dissolved oxygen (DO), pH and phosphorus data were collected in Lake Okeechobee, a shallow lake in south Florida, during a storm event in early 1993. Measured field data indicate that wind and wind-generated waves are major factors responsible for sediment resuspension in the lake. Data also show that soluble reactive phosphorus (SRP) and total dissolved phosphorus (TDP) were inversely-correlated with the DO concentration in the water column. This paper focuses on the use of a vertical one-dimensional model coupling phosphorus dynamics with hydrodynamics and sediment transport processes to simulate the observed episodic event. Model simulations confirmed that resuspension of sediments occurred during the episodic event, with the subsequent increases in phosphorus concentrations. Model results suggest that release of SRP from suspended sediment particles increases as the DO concentration in the water column decreases. By fitting simulated results with field data, an empirical formula describing the effect of the DO concentration on the release of inorganic phosphorus from resuspended sediments has been obtained. Further research to elucidate the detailed mechanism is recommended. Keywords: phosphorus dynamics; hydrodynamics; sediment transport processes; wind-induced waves; real-time simulation; shallow lake; Lake Okeechobee; release of inorganic phosphorus from sediments View Full Text ArticleSubscribe Affiliations: a Surface Water Improvement and Management Program, Southwest Florida Water Management District, Tampa, FL b Formerly Coastal & Oceanographic Engineering Program, University of Florida, Gainesville, FL c Coastal and Oceanographic Engineering Program, University of Florida, Gainesville, FL DOI: 10.1080/07438140309353942 Published in: Lake and Reservoir Management, Volume 19, Issue 4 December 2003 , pages 323 - 340 Publication Frequency: 4 issues per year First Published on: 01 December 2003 Formats available: PDF (English) Wind, current, suspended sediment, dissolved oxygen (DO), pH and phosphorus data were collected in Lake Okeechobee, a shallow lake in south Florida, during a storm event in early 1993. Measured field data indicate that wind and wind-generated waves are major factors responsible for sediment resuspension in the lake. Data also show that soluble reactive phosphorus (SRP) and total dissolved phosphorus (TDP) were inversely-correlated with the DO concentration in the water column. This paper focuses on the use of a vertical one-dimensional model coupling phosphorus dynamics with hydrodynamics and sediment transport processes to simulate the observed episodic event. Model simulations confirmed that resuspension of sediments occurred during the episodic event, with the subsequent increases in phosphorus concentrations. Model results suggest that release of SRP from suspended sediment particles increases as the DO concentration in the water column decreases. By fitting simulated results with field data, an empirical formula describing the effect of the DO concentration on the release of inorganic phosphorus from resuspended sediments has been obtained. Further research to elucidate the detailed mechanism is recommended.
Cylindrospermopsis racihorskii in Three Central Florida Lakes: Population Dynamics, Controls, and Management ImplicationsDean R. DobberfuhlLake and Reservoir Management1040-23810743-81411942003341 - 348Cylindrospermopsis racihorskii in Three Central Florida Lakes: Population Dynamics, Controls, and Management Implications Author: Dean R. Dobberfuhla Abstract Cylindrospermopsis racihorskii is a potentially toxic cyanobacterium that has begun appearing, or alternatively, increasing, and has come to dominate some Florida water bodies. C. racihorskii began exponentially increasing in Lake Jesup, Florida around 1997. As a result, the phytoplankton community in the lake has declined in terms of species richness and diversity. Compared to other lakes in the region this species is still maintaining relatively dynamic population cycles in the lake. Lake stage appears to affect C. racihorskii differently than the aggregate phytoplankton community in Lake Jesup. Correlation analysis suggests that magnesium limitation, among other factors, may be an important factor influencing C. racihorskii growth in Lake Jesup, but appears absent in Lake Apopka and Lake Griffin. Finally, increases in C. racihorskii are associated with increases in phytoplankton biomass yield per unit phosphorus, having important implications for lake management and restoration. Keywords: Cylindrospermopsis racihorskii; Florida; lake stage; magnesium limitation; P use efficiency View Full Text ArticleSubscribe Affiliation: a Division of Environmental Sciences, St. Johns River Water Management, District, Palatka, FL DOI: 10.1080/07438140309353943 Published in: Lake and Reservoir Management, Volume 19, Issue 4 December 2003 , pages 341 - 348 Publication Frequency: 4 issues per year First Published on: 01 December 2003 Formats available: PDF (English) Cylindrospermopsis racihorskii is a potentially toxic cyanobacterium that has begun appearing, or alternatively, increasing, and has come to dominate some Florida water bodies. C. racihorskii began exponentially increasing in Lake Jesup, Florida around 1997. As a result, the phytoplankton community in the lake has declined in terms of species richness and diversity. Compared to other lakes in the region this species is still maintaining relatively dynamic population cycles in the lake. Lake stage appears to affect C. racihorskii differently than the aggregate phytoplankton community in Lake Jesup. Correlation analysis suggests that magnesium limitation, among other factors, may be an important factor influencing C. racihorskii growth in Lake Jesup, but appears absent in Lake Apopka and Lake Griffin. Finally, increases in C. racihorskii are associated with increases in phytoplankton biomass yield per unit phosphorus, having important implications for lake management and restoration.
Predicting the Frequencies of High Chlorophyll Levels in Florida Lakes from Average Chlorophyll or Nutrient DataRoger W. Bachmann; Mark V. Hoyer; Daniel E. Canfield Jr.Lake and Reservoir Management1040-23810743-81411932003229 - 241Predicting the Frequencies of High Chlorophyll Levels in Florida Lakes from Average Chlorophyll or Nutrient Data Authors: Roger W. Bachmanna; Mark V. Hoyera; Daniel E. Canfield Jr.a Abstract An alternative to using average concentrations of phytoplankton chlorophyll in setting lake management goals is to use the frequency that chlorophyll concentrations exceed an established nuisance level. We analyzed 1473 lake-years of data on 438 Florida lakes to develop a series of tables that can be used to predict the frequencies that phytoplankton chlorophylls will exceed concentrations of 10, 20, 30, 40, 50, and 60 mg m-3 in Florida lakes based on the annual average concentrations of chlorophyll, total phosphorus, or total nitrogen. Different tables were created for lakes grouped by TN/TP ratios of >17, <17 but >10, and <10. These tables can be directly applied towards setting lake management goals for those Florida lakes that lack sufficient data to construct their own bloom frequency curves. Keywords: subtropical lakes; phosphorus; nitrogen; chlorophyll; water quality; bloom frequencies View Full Text ArticleSubscribe Affiliation: a Department of Fisheries and Aquatic Sciences, University of Florida, Gainesville, FL, USA DOI: 10.1080/07438140309354088 Published in: Lake and Reservoir Management Publication Frequency: 4 issues per year First Published on: 01 September 2003 Formats available: PDF (English) An alternative to using average concentrations of phytoplankton chlorophyll in setting lake management goals is to use the frequency that chlorophyll concentrations exceed an established nuisance level. We analyzed 1473 lake-years of data on 438 Florida lakes to develop a series of tables that can be used to predict the frequencies that phytoplankton chlorophylls will exceed concentrations of 10, 20, 30, 40, 50, and 60 mg m-3 in Florida lakes based on the annual average concentrations of chlorophyll, total phosphorus, or total nitrogen. Different tables were created for lakes grouped by TN/TP ratios of >17, <17 but >10, and <10. These tables can be directly applied towards setting lake management goals for those Florida lakes that lack sufficient data to construct their own bloom frequency curves.
Assessment of Social and Economic Factors For Management of Summer Pejerrey Recreational Fisheries in Pampean Lakes (Argentina)Claudio R. M. Baigún; Ricardo L. DelfinoLake and Reservoir Management1040-23810743-81411932003242 - 250Assessment of Social and Economic Factors For Management of Summer Pejerrey Recreational Fisheries in Pampean Lakes (Argentina) Authors: Claudio R. M. Baigna; Ricardo L. Delfinob Abstract This study illustrates the importance of assessing social and economic variables for management of recreational pejerrey fisheries in Pampean lakes. We conclude that summer pejerrey anglers differed by lakes in their motivations, preferences, and economic valuation of their fisheries and that most of the differences were attributed to travel distance, facilities, and quality of the fishery. We surveyed four fisheries located in different geographical areas, assessing preference and motivation by interviewing boat anglers at access points and then applying the contingent value method to assess economic values under current and different management conditions, (greater catch or larger size). Results indicated that anglers considered factors other than catching fish to be important, and a continuum of preferences and motivations was observed on a regional basis. Economic analysis yielding expenditures for study lakes averaged US$ 126,000. Consumer surplus for current conditions averaged 30% greater than actual trip costs. Under the preferred management option for the better fishing (greater catch or larger size, depending on the lake), average consumer surplus increased 65% over current expenditures, to US $208,000 per lake. The combination of socio-economic information representing non-market goods with traditional biological and fishery data will provide more comprehensive management criteria to achieve sustainable pejerrey fisheries in Pampean lakes. Keywords: pejerrey; Pampean lakes; contingent value method; consumer surplus; recreational fishery View Full Text ArticleSubscribe Affiliations: a Instituto Tecnolgico de Chascoms, (11B-INTECH), CONICET - Univer Sidad National de San Martin, de Buenos Aires, Argentina b Directin de Recursos Ictcolas y Acucolas, Buenos Aires, Argentina DOI: 10.1080/07438140309354089 Published in: Lake and Reservoir Management, Volume 19, Issue 3 September 2003 , pages 242 - 250 Publication Frequency: 4 issues per year First Published on: 01 September 2003 Formats available: PDF (English) This study illustrates the importance of assessing social and economic variables for management of recreational pejerrey fisheries in Pampean lakes. We conclude that summer pejerrey anglers differed by lakes in their motivations, preferences, and economic valuation of their fisheries and that most of the differences were attributed to travel distance, facilities, and quality of the fishery. We surveyed four fisheries located in different geographical areas, assessing preference and motivation by interviewing boat anglers at access points and then applying the contingent value method to assess economic values under current and different management conditions, (greater catch or larger size). Results indicated that anglers considered factors other than catching fish to be important, and a continuum of preferences and motivations was observed on a regional basis. Economic analysis yielding expenditures for study lakes averaged US$ 126,000. Consumer surplus for current conditions averaged 30% greater than actual trip costs. Under the preferred management option for the better fishing (greater catch or larger size, depending on the lake), average consumer surplus increased 65% over current expenditures, to US $208,000 per lake. The combination of socio-economic information representing non-market goods with traditional biological and fishery data will provide more comprehensive management criteria to achieve sustainable pejerrey fisheries in Pampean lakes.
Phosphorus–Algal Bloom Relationships in Large Lakes of South Florida: Implications for Establishing Nutrient CriteriaKarl E. HavensLake and Reservoir Management1040-23810743-81411932003222 - 228Phosphorus-Algal Bloom Relationships in Large Lakes of South Florida: Implications for Establishing Nutrient Criteria Author: Karl E. Havensa Abstract A simple cross-tabulation procedure was used to examine the relationship between total phosphorus (TP) concentration and algal bloom frequencies, based on chlorophyll a (Chl a), in seven large south Florida lakes. Monthly data from 1995-2000 were sorted by lake and TP concentration. For each lake, the sorted data were sub-divided into five intervals of equal sample size, and the frequency of occurrence of Chl a >20, 40, and 60 μg L-1 was determined and plotted against the median TP in each interval. “Critical” TP concentrations, at which there was a rapid increase in bloom frequency, were examined by visual inspection of these plots. There was considerable variation among lakes in regard to relationship of bloom frequency to TP. For Chl a >20 μg L-1, a rapid rise in frequency occurred at TP ranging from below 30 to greater than 40 μg L-1. For Chl a >40 μg L-1, a rapid rise in frequency began at TP concentrations ranging from 40 to above 70 μg L-1. The variation between lakes was not related to lake water total or dissolved N:P, but it was strongly related to color. Color explained 86% of the variation between lakes in terms of critical TP for increased frequency of Chl a >40 μg L-1, which is defined as an algal bloom by the State of Florida. Color, which reduces light penetration, may be particularly important in these lakes because they typically have homogeneous water columns that do not allow algae to migrate to and sustain high biomass near the surface, where there is adequate light for net growth. The influence of color is probably less in lakes with stable thermal stratification. The simple method used to evaluate the seven lakes could be generally applied, making use of routine water quality monitoring data, as long as one could specify an appropriate Chl a concentration and frequency for protecting the major use of particular water resources. Keywords: total phosphorus; chlorophyll a; bloom frequency analysis; numeric criteria View Full Text ArticleSubscribe Affiliation: a South Florida Water Management District, West Palm Beach, FL, USA DOI: 10.1080/07438140309354087 Published in: Lake and Reservoir Management, Volume 19, Issue 3 September 2003 , pages 222 - 228 Publication Frequency: 4 issues per year First Published on: 01 September 2003 Formats available: PDF (English) A simple cross-tabulation procedure was used to examine the relationship between total phosphorus (TP) concentration and algal bloom frequencies, based on chlorophyll a (Chl a), in seven large south Florida lakes. Monthly data from 1995-2000 were sorted by lake and TP concentration. For each lake, the sorted data were sub-divided into five intervals of equal sample size, and the frequency of occurrence of Chl a >20, 40, and 60 μg L-1 was determined and plotted against the median TP in each interval. “Critical” TP concentrations, at which there was a rapid increase in bloom frequency, were examined by visual inspection of these plots. There was considerable variation among lakes in regard to relationship of bloom frequency to TP. For Chl a >20 μg L-1, a rapid rise in frequency occurred at TP ranging from below 30 to greater than 40 μg L-1. For Chl a >40 μg L-1, a rapid rise in frequency began at TP concentrations ranging from 40 to above 70 μg L-1. The variation between lakes was not related to lake water total or dissolved N:P, but it was strongly related to color. Color explained 86% of the variation between lakes in terms of critical TP for increased frequency of Chl a >40 μg L-1, which is defined as an algal bloom by the State of Florida. Color, which reduces light penetration, may be particularly important in these lakes because they typically have homogeneous water columns that do not allow algae to migrate to and sustain high biomass near the surface, where there is adequate light for net growth. The influence of color is probably less in lakes with stable thermal stratification. The simple method used to evaluate the seven lakes could be generally applied, making use of routine water quality monitoring data, as long as one could specify an appropriate Chl a concentration and frequency for protecting the major use of particular water resources.
Application of a Probabilistic Ammonia Model: Identification of Important Model Inputs and Critique of a TMDL Analysis for an Urban LakeRakesh K. Gelda; Steven W. EfflerLake and Reservoir Management1040-23810743-81411932003187 - 199Application of a Probabilistic Ammonia Model: Identification of Important Model Inputs and Critique of a TMDL Analysis for an Urban Lake Authors: Rakesh K. Geldaa; Steven W. Efflera Abstract Modeling analyses are conducted with a probabilistic mass balance ammonia model to demonstrate the important role that specifications of model inputs and toxicity standards by regulators can play in determining the assimilative capacity of polluted Onondaga Lake, NY, and to support a critical review of a related Total Maximum Daily Load (TMDL) analysis. More than 90% of the ammonia received by the lake is from a municipal wastewater treatment plant (Metro). It was found that various decisions to be made by regulators in management applications of the model greatly influence the lake's apparent assimilative capacity (TMDL). In particular, the following issues were critical: (1) anticipated hypolimnetic oxygenation treatment, (2) previously documented in-lake nitrification events, (3) effects of residual industrial pollution on pH, (4) effects of uncertainties and potential bias in pH measurements, (5) anticipated increases in population growth served by Metro, and (6) revisions in national guidance toxicity criteria prepared by the U. S. Environmental Protection Agency. Several limitations in the existing ammonia TMDL analysis are reported, including: (1) arbitrary specification of critical conditions, (2) omission of the important features of duration and allowable number of occurrences in the state standard, (3) identification of the wrong month as critical for determining the lake's assimilative capacity, (4) lack of recognition of the artificial assimilative capacity associated with the effects of residual industrial pollution, (5) the specified “margin of safety” was too low, given the level of modeling and input uncertainties, (6) anticipated increases in discharge from Metro were not considered, and (7) incorrect identification of the critical year for tributary hydrology. Recommendations are made to upgrade the ammonia TMDL analysis, including the supporting model framework and data sets. Keywords: TMDL; ammonia; modeling; toxicity; probabilistic; Monte Carlo; nitrogen; lakes View Full Text ArticleSubscribe Affiliation: a Upstate Freshwater Institute, Syracuse, NY DOI: 10.1080/07438140309354084 Published in: Lake and Reservoir Management, Volume 19, Issue 3 September 2003 , pages 187 - 199 Publication Frequency: 4 issues per year First Published on: 01 September 2003 Formats available: PDF (English) Modeling analyses are conducted with a probabilistic mass balance ammonia model to demonstrate the important role that specifications of model inputs and toxicity standards by regulators can play in determining the assimilative capacity of polluted Onondaga Lake, NY, and to support a critical review of a related Total Maximum Daily Load (TMDL) analysis. More than 90% of the ammonia received by the lake is from a municipal wastewater treatment plant (Metro). It was found that various decisions to be made by regulators in management applications of the model greatly influence the lake's apparent assimilative capacity (TMDL). In particular, the following issues were critical: (1) anticipated hypolimnetic oxygenation treatment, (2) previously documented in-lake nitrification events, (3) effects of residual industrial pollution on pH, (4) effects of uncertainties and potential bias in pH measurements, (5) anticipated increases in population growth served by Metro, and (6) revisions in national guidance toxicity criteria prepared by the U. S. Environmental Protection Agency. Several limitations in the existing ammonia TMDL analysis are reported, including: (1) arbitrary specification of critical conditions, (2) omission of the important features of duration and allowable number of occurrences in the state standard, (3) identification of the wrong month as critical for determining the lake's assimilative capacity, (4) lack of recognition of the artificial assimilative capacity associated with the effects of residual industrial pollution, (5) the specified “margin of safety” was too low, given the level of modeling and input uncertainties, (6) anticipated increases in discharge from Metro were not considered, and (7) incorrect identification of the critical year for tributary hydrology. Recommendations are made to upgrade the ammonia TMDL analysis, including the supporting model framework and data sets.
The Potential Impact of Water Reallocation on Retention and Chlorophyll a in Weiss Lake, AlabamaMichael J. Maceina; David R. BayneLake and Reservoir Management1040-23810743-81411932003200 - 207The Potential Impact of Water Reallocation on Retention and Chlorophyll a in Weiss Lake, Alabama Authors: Michael J. Maceinaa; David R. Baynea Abstract Water supply demand has increased in North Georgia and prompted government officials to propose a water reallocation plan that would permit two reservoirs upstream from Weiss Lake, Alabama to increase water withdrawals nearly three fold. Hydrologic modeling predicted lower flows in the Coosa River, the primary tributary of Weiss Lake, during average to below average flows (exceedences from 50 to 90%). Consequently, we predicted retention (reservoir volume/discharge) would increase in Weiss Lake under reallocation and using data from 1989 to 2000 as a baseline, we estimated the effect of longer retention on chlorophyll a concentrations (CHLA) and water clarity. CHLA measured during the growing season (April to October) was positively correlated (P < 0.01) to retention in both upstream and downstream reservoir regions and retention accounted for 24 to 28% of the variation in CHLA in linear and non-linear regression models. Under the reallocation scheme, increased retention (as predicted by HEC-5) could potentially cause an increase in CHLA of 8 to 15% compared to historic conditions if CHLA increased linearly with retention. If retention should increase 10 days with water reallocation, we estimated CHLA could increase about 20 to 30% under a “worst-case scenario”. Water reallocation would have little or no impact on water clarity as Secchi transparency did not increase with lower CHLA concentrations. If longer retention does occur in Weiss Lake with water reallocation, a greater frequency of hypereutrophic conditions is expected. Keywords: chlorophyll a; retention; water reallocation; water clarity; algal blooms View Full Text ArticleSubscribe Affiliation: a Department of Fisheries, Auburn University, Alabama DOI: 10.1080/07438140309354085 Published in: Lake and Reservoir Management, Volume 19, Issue 3 September 2003 , pages 200 - 207 Publication Frequency: 4 issues per year First Published on: 01 September 2003 Formats available: PDF (English) Water supply demand has increased in North Georgia and prompted government officials to propose a water reallocation plan that would permit two reservoirs upstream from Weiss Lake, Alabama to increase water withdrawals nearly three fold. Hydrologic modeling predicted lower flows in the Coosa River, the primary tributary of Weiss Lake, during average to below average flows (exceedences from 50 to 90%). Consequently, we predicted retention (reservoir volume/discharge) would increase in Weiss Lake under reallocation and using data from 1989 to 2000 as a baseline, we estimated the effect of longer retention on chlorophyll a concentrations (CHLA) and water clarity. CHLA measured during the growing season (April to October) was positively correlated (P < 0.01) to retention in both upstream and downstream reservoir regions and retention accounted for 24 to 28% of the variation in CHLA in linear and non-linear regression models. Under the reallocation scheme, increased retention (as predicted by HEC-5) could potentially cause an increase in CHLA of 8 to 15% compared to historic conditions if CHLA increased linearly with retention. If retention should increase 10 days with water reallocation, we estimated CHLA could increase about 20 to 30% under a “worst-case scenario”. Water reallocation would have little or no impact on water clarity as Secchi transparency did not increase with lower CHLA concentrations. If longer retention does occur in Weiss Lake with water reallocation, a greater frequency of hypereutrophic conditions is expected.
Hypolimnetic Anoxia and Sediment Oxygen Demand in California Drinking Water ReservoirsMarc W. BeutelLake and Reservoir Management1040-23810743-81411932003208 - 221Hypolimnetic Anoxia and Sediment Oxygen Demand in California Drinking Water Reservoirs Author: Marc W. Beutela Abstract Summertime hypolimnetic anoxia can occur in productive drinking water reservoirs as a result of the decay of phytoplankton. Anoxic conditions promote ecological processes that degrade water quality through the release of problem-causing compounds from anoxic sediments including phosphates, ammonia, sulfides, methyl-mercury, iron and manganese. Hypolimnetic aeration systems are commonly installed in reservoirs to prevent hypolimnetic anoxia, but these systems have been historically undersized due to an underestimation of the magnitude of oxygen demand in the hypolimnion. To gain insight into the sizing of hypolimnetic aeration systems, this study evaluated the effects of water current and DO concentration near the sediment-water interface on sediment oxygen demand (SOD) in nine California drinking water reservoirs of various size (5-220 million m3) and trophic status (mean annual chlorophyll a of 0.5-11 μg L-1). SOD measured under quiescent conditions in 1.8 L experimental chambers ranged from 0.1-0.8 g m2 d1 Currents near the sediment-water interface of 3-8 cm s1 induced a two to four-fold increase in SOD, and resulted in a shift from first-order to zero-order DO uptake by sediment with respect to DO concentration in overlaying water. Results support the diffusive boundary layer model for SOD, with increased DO concentration and currents resulting in a larger SOD since there is a greater diffusional driving force across a smaller diffusive boundary layer. The study also evaluated the effects of trophic status and morphometry on hypolimnetic anoxia at the nine study sites. A number of significant correlations were discovered between factor quantifying hypolimnetic anoxia (areal and mass based hypolimnetic oxygen demand, SOD) and those quantifying morphometry (mean depth of the hypolimnion, volume of the hypolimnion) and trophic status (mean annual chlorophyll a). These results suggest that both increased size of the hypolimnion and higher productivity lead to higher oxygen demand within the hypolimnion. In addition, shallower reservoirs had a larger fraction of their total oxygen demand exerted in the sediments versus the water column. As a result, increased mixing at the sediment-water interface after start-up of aeration systems, and the resulting stimulation of SOD, will be particularly important in productive reservoirs of moderate depth (mean depth of 10-15 m). Aeration systems should be designed to enhance SOD by maintaining high oxygen concentrations and by inducing currents at the sediment-water interface. This will increase the depth of penetration of DO into sediment and promote beneficial aerobic biogeochemical reactions in surface sediments. Aeration systems that utilize pure-oxygen with horizontal discharge of highly oxygenated water across the sediment surface, rather than the traditional air-lift aeration system, will be more successful in satisfying SOD and improving hypolimnetic water quality. Keywords: hypolimnetic anoxia; hypolimnetic aeration; sediment oxygen demand; reservoir View Full Text ArticleSubscribe Affiliation: a Brown and Caldwell, Walnut Creek, California DOI: 10.1080/07438140309354086 Published in: Lake and Reservoir Management, Volume 19, Issue 3 September 2003 , pages 208 - 221 Publication Frequency: 4 issues per year First Published on: 01 September 2003 Formats available: PDF (English) Summertime hypolimnetic anoxia can occur in productive drinking water reservoirs as a result of the decay of phytoplankton. Anoxic conditions promote ecological processes that degrade water quality through the release of problem-causing compounds from anoxic sediments including phosphates, ammonia, sulfides, methyl-mercury, iron and manganese. Hypolimnetic aeration systems are commonly installed in reservoirs to prevent hypolimnetic anoxia, but these systems have been historically undersized due to an underestimation of the magnitude of oxygen demand in the hypolimnion. To gain insight into the sizing of hypolimnetic aeration systems, this study evaluated the effects of water current and DO concentration near the sediment-water interface on sediment oxygen demand (SOD) in nine California drinking water reservoirs of various size (5-220 million m3) and trophic status (mean annual chlorophyll a of 0.5-11 μg L-1). SOD measured under quiescent conditions in 1.8 L experimental chambers ranged from 0.1-0.8 g m2 d1 Currents near the sediment-water interface of 3-8 cm s1 induced a two to four-fold increase in SOD, and resulted in a shift from first-order to zero-order DO uptake by sediment with respect to DO concentration in overlaying water. Results support the diffusive boundary layer model for SOD, with increased DO concentration and currents resulting in a larger SOD since there is a greater diffusional driving force across a smaller diffusive boundary layer. The study also evaluated the effects of trophic status and morphometry on hypolimnetic anoxia at the nine study sites. A number of significant correlations were discovered between factor quantifying hypolimnetic anoxia (areal and mass based hypolimnetic oxygen demand, SOD) and those quantifying morphometry (mean depth of the hypolimnion, volume of the hypolimnion) and trophic status (mean annual chlorophyll a). These results suggest that both increased size of the hypolimnion and higher productivity lead to higher oxygen demand within the hypolimnion. In addition, shallower reservoirs had a larger fraction of their total oxygen demand exerted in the sediments versus the water column. As a result, increased mixing at the sediment-water interface after start-up of aeration systems, and the resulting stimulation of SOD, will be particularly important in productive reservoirs of moderate depth (mean depth of 10-15 m). Aeration systems should be designed to enhance SOD by maintaining high oxygen concentrations and by inducing currents at the sediment-water interface. This will increase the depth of penetration of DO into sediment and promote beneficial aerobic biogeochemical reactions in surface sediments. Aeration systems that utilize pure-oxygen with horizontal discharge of highly oxygenated water across the sediment surface, rather than the traditional air-lift aeration system, will be more successful in satisfying SOD and improving hypolimnetic water quality.
NewsG. DennisLake and Reservoir Management1040-23810743-81411932003280News Author: G. Dennis View Full Text ArticleSubscribe DOI: 10.1080/07438140309354093 Published in: Lake and Reservoir Management, Volume 19, Issue 3 September 2003 , page 280 Publication Frequency: 4 issues per year First Published on: 01 September 2003 Formats available: PDF (English)
Book ReviewJames J. SartorisLake and Reservoir Management1040-23810743-81411932003281Book Review Author: James J. Sartorisa View Full Text ArticleSubscribe Affiliation: a Biological Resources Division, U.S. Geological Survey, Denvor, Colorado, USA DOI: 10.1080/07438140309354094 Published in: Lake and Reservoir Management, Volume 19, Issue 3 September 2003 , page 281 Publication Frequency: 4 issues per year First Published on: 01 September 2003 Formats available: PDF (English)
2003 OFFICERS & DIRECTORSLake and Reservoir Management1040-23810743-814119320032822003 OFFICERS & DIRECTORS View Full Text ArticleSubscribe DOI: 10.1080/07438140309354095 Published in: Lake and Reservoir Management, Volume 19, Issue 3 September 2003 , page 282 Publication Frequency: 4 issues per year First Published on: 01 September 2003 Formats available: PDF (English)
An Alternative to Proposed Phosphorus TMDLs for the Management of Lake OkeechobeeRoger W. Bachmann; Mark V. Hoyer; Carlos Fernandez; Daniel E. Canfield Jr.Lake and Reservoir Management1040-23810743-81411932003251 - 264An Alternative to Proposed Phosphorus TMDLs for the Management of Lake Okeechobee Authors: Roger W. Bachmanna; Mark V. Hoyera; Carlos Fernandezb; Daniel E. Canfield Jr.a Abstract The U.S. Environmental Protection Agency and the Florida Department of Environmental Protection recently proposed total maximum daily loads (TMDL) of phosphorus for Lake Okeechobee of 198 t yr-1 and 140 t yr-1, respectively, with a goal of limiting algal blooms in the near-shore areas of the lake. We evaluated the reasonableness of these regulations by examining evidence of past changes in the lake, factors determining water quality, current phosphorus targets for the pelagic water, factors determining total phosphorus levels in the lake, expected benefits of the proposed TMDLs, and alternative management options. Available data are insufficient to demonstrate the degree of any recent eutrophication of the lake. Movement of the sediments in this shallow lake, perhaps by hurricane generated currents, casts doubt on reconstructions of lake history through sediment cores. We estimated presettlement phosphorus loading of 377 t yr-1, indicating that the lake has been eutrophic for a hundred or more years. The pelagic region of the lake is dominated by resuspended sediments that increase the phosphorus concentration and reduce light transmission. Thus, algal populations are limited by light and not phosphorus. As a result, there is no correlation between phosphorus and plankton chlorophylls and only a very weak correlation (r = 0.26) between Secchi depth and chlorophyll a. Living plankton account for only 15% of the total suspended solids in the pelagic region. Phosphorus targets for Lake Okeechobee have been based on conditions in the near-shore region along the western marshes. A concentration of 40 mg m3 of TP in the near-shore region would limit the frequency of algal blooms (chlorophyll a> mg m-3) to 15% of the year, the lowest bloom frequency observed in the closest pelagic stations in the past 28 years. Models indicate mat this frequency can be achieved with a pelagic TP concentration of between 72 and 92 mg m-3, though the TMDL models use 40 mg m-3 as their pelagic target TP concentration. Phosphorus levels in the pelagic region are not correlated with phosphorus inputs, so in spite of recent decreases in phosphorus loading to the lake, phosphorus concentrations continue to rise. This seems to be due to a reduction in phosphorus retention by the lake since 1973. The reason for the loss of phosphorus retention is not known, though there are indications that rising water levels and/or declining calcium concentrations might be involved. The data do not demonstrate that stringent phosphorus TMDLs will improve the lake. On the other hand, there is evidence that high water levels are responsible for reduced water quality in the lake and loss of macrophytes. A planned reduction in lake stage in 2000 made significant improvements in plant coverage, water clarity, and fish habitat without any change in the phosphorus regime. Water level controls seem to have more promise as a management tool for Lake Okeechobee than TMDLs for phosphorus. Keywords: restoration; eutrophication; aquatic macrophytes; phosphorus; lake management View Full Text ArticleSubscribe Affiliations: a Department of Fisheries and Aquatic Sciences, University of Florida, Gainesville, FL, USA b Hillsborough County Public Works Dept., Tampa, FL DOI: 10.1080/07438140309354090 Published in: Lake and Reservoir Management, Volume 19, Issue 3 September 2003 , pages 251 - 264 Publication Frequency: 4 issues per year First Published on: 01 September 2003 Formats available: PDF (English) The U.S. Environmental Protection Agency and the Florida Department of Environmental Protection recently proposed total maximum daily loads (TMDL) of phosphorus for Lake Okeechobee of 198 t yr-1 and 140 t yr-1, respectively, with a goal of limiting algal blooms in the near-shore areas of the lake. We evaluated the reasonableness of these regulations by examining evidence of past changes in the lake, factors determining water quality, current phosphorus targets for the pelagic water, factors determining total phosphorus levels in the lake, expected benefits of the proposed TMDLs, and alternative management options. Available data are insufficient to demonstrate the degree of any recent eutrophication of the lake. Movement of the sediments in this shallow lake, perhaps by hurricane generated currents, casts doubt on reconstructions of lake history through sediment cores. We estimated presettlement phosphorus loading of 377 t yr-1, indicating that the lake has been eutrophic for a hundred or more years. The pelagic region of the lake is dominated by resuspended sediments that increase the phosphorus concentration and reduce light transmission. Thus, algal populations are limited by light and not phosphorus. As a result, there is no correlation between phosphorus and plankton chlorophylls and only a very weak correlation (r = 0.26) between Secchi depth and chlorophyll a. Living plankton account for only 15% of the total suspended solids in the pelagic region. Phosphorus targets for Lake Okeechobee have been based on conditions in the near-shore region along the western marshes. A concentration of 40 mg m3 of TP in the near-shore region would limit the frequency of algal blooms (chlorophyll a> mg m-3) to 15% of the year, the lowest bloom frequency observed in the closest pelagic stations in the past 28 years. Models indicate mat this frequency can be achieved with a pelagic TP concentration of between 72 and 92 mg m-3, though the TMDL models use 40 mg m-3 as their pelagic target TP concentration. Phosphorus levels in the pelagic region are not correlated with phosphorus inputs, so in spite of recent decreases in phosphorus loading to the lake, phosphorus concentrations continue to rise. This seems to be due to a reduction in phosphorus retention by the lake since 1973. The reason for the loss of phosphorus retention is not known, though there are indications that rising water levels and/or declining calcium concentrations might be involved. The data do not demonstrate that stringent phosphorus TMDLs will improve the lake. On the other hand, there is evidence that high water levels are responsible for reduced water quality in the lake and loss of macrophytes. A planned reduction in lake stage in 2000 made significant improvements in plant coverage, water clarity, and fish habitat without any change in the phosphorus regime. Water level controls seem to have more promise as a management tool for Lake Okeechobee than TMDLs for phosphorus.
Limited Effects of Barley Straw on Algae and Zooplankton in a Midwestern PondJoseph D. Boylan; Joseph E. MorrisLake and Reservoir Management1040-23810743-81411932003265 - 271Limited Effects of Barley Straw on Algae and Zooplankton in a Midwestern Pond Authors: Joseph D. Boylana; Joseph E. Morrisa Abstract Researchers in the United Kingdom have reported that barley straw can be used to control a variety of planktonic algae, as well as the filamentous alga Cladophora spp. This method appears to be cost-effective, user-friendly, and environmentally sound. If these results could be obtained in the United States, using barley straw would be a good alternative to using copper sulfate. However, research has shown that barley straw must be subjected to well-oxygenated water for it to become anti-algal. Consequently, the sites of most studies conducted in the UK in which barley straw showed an effect have been somewhat lotic. Midwestern ponds are typically stagnant, and often become oxygen-poor during summer months, and therefore it is questionable whether barley straw would work. We attempted to control algae (filamentous and planktonic) growing in replicated limnocorrals that were built inside of a 1-ha pond; limnocorrals were stocked with three levels of barley straw. In addition, we tested whether the straw had effects on zooplankton community structure. No consistent degree of algal growth inhibition was observed for either alga type, and zooplankton community structure was not affected throughout this 14-week study (P < 0.10). Our results, as well as those of some other US researchers, may be partly explained by inadequate levels of oxygen within the decomposing straw caused by a lack of water exchange between the interstices of the straw and the water body. Keywords: barley straw; algae; zooplankton View Full Text ArticleSubscribe Affiliation: a Department of Animal Ecology, Iowa State University, Ames, IA DOI: 10.1080/07438140309354091 Published in: Lake and Reservoir Management, Volume 19, Issue 3 September 2003 , pages 265 - 271 Publication Frequency: 4 issues per year First Published on: 01 September 2003 Formats available: PDF (English) Researchers in the United Kingdom have reported that barley straw can be used to control a variety of planktonic algae, as well as the filamentous alga Cladophora spp. This method appears to be cost-effective, user-friendly, and environmentally sound. If these results could be obtained in the United States, using barley straw would be a good alternative to using copper sulfate. However, research has shown that barley straw must be subjected to well-oxygenated water for it to become anti-algal. Consequently, the sites of most studies conducted in the UK in which barley straw showed an effect have been somewhat lotic. Midwestern ponds are typically stagnant, and often become oxygen-poor during summer months, and therefore it is questionable whether barley straw would work. We attempted to control algae (filamentous and planktonic) growing in replicated limnocorrals that were built inside of a 1-ha pond; limnocorrals were stocked with three levels of barley straw. In addition, we tested whether the straw had effects on zooplankton community structure. No consistent degree of algal growth inhibition was observed for either alga type, and zooplankton community structure was not affected throughout this 14-week study (P < 0.10). Our results, as well as those of some other US researchers, may be partly explained by inadequate levels of oxygen within the decomposing straw caused by a lack of water exchange between the interstices of the straw and the water body.
Is Littoral Habitat Affected by Residential Development and Land Use in Watersheds of Wisconsin Lakes?Martin J. Jennings; Edward E. Emmons; Gene R. Hatzenbeler; Clayton Edwards; Michael A. BozekLake and Reservoir Management1040-23810743-81411932003272 - 279Is Littoral Habitat Affected by Residential Development and Land Use in Watersheds of Wisconsin Lakes? Authors: Martin J. Jenningsa; Edward E. Emmonsb; Gene R. Hatzenbelerc; Clayton Edwardsd; Michael A. Bozekc Abstract We measured differences in nearshore littoral zone habitat among lakes with different amounts of residential development and different patterns of watershed land use. Sampling stations were located at randomly selected sites within the nearshore littoral zone of limnologically similar lakes. An index of development density (based on counts of residential structures) and watershed cover types detected by satellite imagery summarized human influence in the riparian zone and watershed. To compare effects of development at local sites to effects of cumulative development density (structures/km shoreline), we used analysis of covariance. Quantity of woody debris, emergent vegetation and floating vegetation decreased at developed sites and in lakes with greater cumulative lakeshore development density. Littoral sediments contained more fine particles at developed sites and in lakes with greater development density. Sediment composition, quantity of vegetation, and woody debris were weakly associated with differences in watershed land use. Cumulative changes to watersheds and riparian zones are associated with measurable differences in littoral habitat that may not be detectable at smaller scales. For effective conservation, regulatory programs should consider the cumulative effects of development and land use on aquatic systems. Keywords: aquatic habitat; lakes; land use; development; spatial scale; macrophytes; substrate; woody debris View Full Text ArticleSubscribe Affiliations: a Wisconsin Department of Natural Resources, Bureau of Integrated Science Services, Spooner, WI b Wisconsin Department of Natural Resources, Bureau of Integrated Science Services, Monona, WI c Wisconsin Cooperative Fishery Research Unit, Biological Resources Division U.S.G.S., University of Wisconsin-Stevens Point, Stevens Point, WI d U.S.D.A. Forest Service, North Central Forest Experimental Station, Rhinelander, WI DOI: 10.1080/07438140309354092 Published in: Lake and Reservoir Management, Volume 19, Issue 3 September 2003 , pages 272 - 279 Publication Frequency: 4 issues per year First Published on: 01 September 2003 Formats available: PDF (English) We measured differences in nearshore littoral zone habitat among lakes with different amounts of residential development and different patterns of watershed land use. Sampling stations were located at randomly selected sites within the nearshore littoral zone of limnologically similar lakes. An index of development density (based on counts of residential structures) and watershed cover types detected by satellite imagery summarized human influence in the riparian zone and watershed. To compare effects of development at local sites to effects of cumulative development density (structures/km shoreline), we used analysis of covariance. Quantity of woody debris, emergent vegetation and floating vegetation decreased at developed sites and in lakes with greater cumulative lakeshore development density. Littoral sediments contained more fine particles at developed sites and in lakes with greater development density. Sediment composition, quantity of vegetation, and woody debris were weakly associated with differences in watershed land use. Cumulative changes to watersheds and riparian zones are associated with measurable differences in littoral habitat that may not be detectable at smaller scales. For effective conservation, regulatory programs should consider the cumulative effects of development and land use on aquatic systems.
Limnology of Shallow Lakes in the Yukon Flats National Wildlife Refuge, Interior AlaskaPatricia J. Heglund; John R. JonesLake and Reservoir Management1040-23810743-81411922003133 - 140Limnology of Shallow Lakes in the Yukon Flats National Wildlife Refuge, Interior Alaska Authors: Patricia J. Heglunda; John R. Jonesa Abstract Data from 129 shallow riverine lakes within the Yukon Flats National Wildlife Refuge (between 65° 45'N and 67° 30'N and 142° 30'W and 150° 00'W) are presented as a baseline contribution to the regional limnology of Alaska. Ion composition reflected the composition of carbonate alluvium within the region; in most lakes Ca > Mg and bicarbonate dominated the anions (~90%). In lakes where alkali deposits occurred, Na, Mg and bicarbonate were the principal ions. Some 25% of the lakes were slightly brackish (conductivity >500 μS) to brackish. The lakes are colored, with 18 to 447 Pt-units. And, they are fertile, with over 70% classified as eu-or hypereutrophic on the basis of their nutrient content. Ratios of N:P suggested nitrogen was potentially limiting in about half the study lakes and was increasingly important at high P values. The yield of algal chlorophyll (Chl) per unit of plant nutrient was low in these lakes and Chl-nutrient relations explained less of the variance relative to published models. Invertebrate grazing potentially regulates Chi in some lakes. Typically these lakes freeze to the sediments and most do not support a permanent fishery. High ratios of organic suspended solids to Chl indicate detrital carbon contributes to the filterable carbon pool of these shallow lakes. Keywords: shallow lakes; water chemistry; colored lakes; nitrogen; phosphorus; algae View Full Text ArticleSubscribe Affiliation: a Department of Fisheries and Wildlife Sciences, University of Missouri, Columbia, MO DOI: 10.1080/07438140309354079 Published in: Lake and Reservoir Management Publication Frequency: 4 issues per year First Published on: 01 June 2003 Formats available: PDF (English) Data from 129 shallow riverine lakes within the Yukon Flats National Wildlife Refuge (between 65° 45'N and 67° 30'N and 142° 30'W and 150° 00'W) are presented as a baseline contribution to the regional limnology of Alaska. Ion composition reflected the composition of carbonate alluvium within the region; in most lakes Ca > Mg and bicarbonate dominated the anions (~90%). In lakes where alkali deposits occurred, Na, Mg and bicarbonate were the principal ions. Some 25% of the lakes were slightly brackish (conductivity >500 μS) to brackish. The lakes are colored, with 18 to 447 Pt-units. And, they are fertile, with over 70% classified as eu-or hypereutrophic on the basis of their nutrient content. Ratios of N:P suggested nitrogen was potentially limiting in about half the study lakes and was increasingly important at high P values. The yield of algal chlorophyll (Chl) per unit of plant nutrient was low in these lakes and Chl-nutrient relations explained less of the variance relative to published models. Invertebrate grazing potentially regulates Chi in some lakes. Typically these lakes freeze to the sediments and most do not support a permanent fishery. High ratios of organic suspended solids to Chl indicate detrital carbon contributes to the filterable carbon pool of these shallow lakes.
General Limnology of Lakes Near Cook Inlet, Southcentral AlaskaJohn R. Jones; Michael A. Bell; John A. Baker; Jeffrey P. KoeningsLake and Reservoir Management1040-23810743-81411922003141 - 149General Limnology of Lakes Near Cook Inlet, Southcentral Alaska Authors: John R. Jonesa; Michael A. Bellb; John A. Bakerc; Jeffrey P. Koeningsde Abstract Data from lakes on the Kenai Peninsula (n = 111) and in the Matanuska-Susitna Valley (n = 108) show that lakes near the Cook Inlet, Alaska are moderately stained, with low turbidity and are predominately oligotrophic with a potential for phosphorus limitation. In both locations measures of salinity (as measured by conductivity) and pH were heterogenous and tied to hydrologic flowpaths. Overall, seepage lakes had lower pH, salinity, alkalinity, Ca, Mg and Si than drainage lakes. In our data set, both seepage and drainage lakes on the Kenai had lower alkalinity, Ca, and Si than corresponding lake types in Mat-Su. Most zooplankton biomass (ZB) measurements in the Cook Inlet lakes were <100 μg L-1 and over one-third were <10 μg L-1. Values of ZB were low relative to empirical models and did not increase with lake trophic state. Each of these lakes supports a fish community and the well-known effects of food web structure via grazing by planktivorous fish likely account for the observed ZB values. Environmental measurements and their patterns match earlier studies and collectively describe extant features of lake resources in this region of the southern boreal forest in southcentral Alaska. Keywords: Alaskan lakes; nitrogen; phosphorus; plankton; seepage lakes; drainage lakes View Full Text ArticleSubscribe Affiliations: a Department of Fisheries and Wildlife Sciences, University of Missouri, Columbia, MO b Department of Ecology and Evolution, State University of New York, Stony Brook, NY c Department of Biology, Clark University, Worcester, MA d Fisheries Rehabilitation, Enhancement and Development Division, Limnology Section, Alaska Department of Fish and Game, Soldotna, AK e Department of Fish and Wildlife, State of Washington, Olympia DOI: 10.1080/07438140309354080 Published in: Lake and Reservoir Management, Volume 19, Issue 2 June 2003 , pages 141 - 149 Publication Frequency: 4 issues per year First Published on: 01 June 2003 Formats available: PDF (English) Data from lakes on the Kenai Peninsula (n = 111) and in the Matanuska-Susitna Valley (n = 108) show that lakes near the Cook Inlet, Alaska are moderately stained, with low turbidity and are predominately oligotrophic with a potential for phosphorus limitation. In both locations measures of salinity (as measured by conductivity) and pH were heterogenous and tied to hydrologic flowpaths. Overall, seepage lakes had lower pH, salinity, alkalinity, Ca, Mg and Si than drainage lakes. In our data set, both seepage and drainage lakes on the Kenai had lower alkalinity, Ca, and Si than corresponding lake types in Mat-Su. Most zooplankton biomass (ZB) measurements in the Cook Inlet lakes were <100 μg L-1 and over one-third were <10 μg L-1. Values of ZB were low relative to empirical models and did not increase with lake trophic state. Each of these lakes supports a fish community and the well-known effects of food web structure via grazing by planktivorous fish likely account for the observed ZB values. Environmental measurements and their patterns match earlier studies and collectively describe extant features of lake resources in this region of the southern boreal forest in southcentral Alaska.
Factors Affecting Iowa Lake and Reservoir Water QualityLorin K. HatchLake and Reservoir Management1040-23810743-81411922003150 - 159Factors Affecting Iowa Lake and Reservoir Water Quality Author: Lorin K. Hatcha Abstract Iowa lake and reservoir water quality data collected during the summers of 1990 and 1992 were analyzed according to origin (lake vs. reservoir) and location, updating previous synoptic surveys. Morphometric comparisons between Iowa regions indicate unique characteristics for reservoirs, glacial lakes, oxbow lakes, and waterbodies on the Des Moines glacial lobe. All Iowa lakes and reservoirs are eutrophic although there is a significant range of water quality and within-region variability. Parameters such as chlorophyll a, total phosphorus (TP), and total nitrogen (TN) summer mean concentrations were highest on the Des Moines glacial lobe (means of 64 μg L-1, 164 μg L-1, and 4.4 mg L-1, respectively). A comparison of northern Iowa versus southern Minnesota lakes and southern Iowa versus northern Missouri reservoirs indicated that Iowa water quality is more eutrophic in both instances. Northern Iowa lakes had higher TN (3.0 mg L-1), total suspended solids (TSS, 39 mg L-1), and non-volatile suspended solids (NVSS, 18 mg L-1) summer mean concentrations than southern Minnesota lakes (2.1 mg L-1, 14 mg L-1, and 3 mg L-1, respectively). Southern Iowa reservoirs had higher TP (149 μg L-1), TN (1.8 mg L-1), TSS (34 mg L-1), and NVSS (25 mg L-1) summer mean concentrations than northern Missouri reservoirs (47 μg L-1, 0.7 mg L-1, 10 mg L-1, and 7 mg L-1, respectively). Keywords: ecoregions; Iowa; Minnesota; Missouri; morphometry; water quality View Full Text ArticleSubscribe Affiliation: a University of Minnesota Water Resources Center, St. Paul, MN DOI: 10.1080/07438140309354081 Published in: Lake and Reservoir Management Publication Frequency: 4 issues per year First Published on: 01 June 2003 Formats available: PDF (English) Iowa lake and reservoir water quality data collected during the summers of 1990 and 1992 were analyzed according to origin (lake vs. reservoir) and location, updating previous synoptic surveys. Morphometric comparisons between Iowa regions indicate unique characteristics for reservoirs, glacial lakes, oxbow lakes, and waterbodies on the Des Moines glacial lobe. All Iowa lakes and reservoirs are eutrophic although there is a significant range of water quality and within-region variability. Parameters such as chlorophyll a, total phosphorus (TP), and total nitrogen (TN) summer mean concentrations were highest on the Des Moines glacial lobe (means of 64 μg L-1, 164 μg L-1, and 4.4 mg L-1, respectively). A comparison of northern Iowa versus southern Minnesota lakes and southern Iowa versus northern Missouri reservoirs indicated that Iowa water quality is more eutrophic in both instances. Northern Iowa lakes had higher TN (3.0 mg L-1), total suspended solids (TSS, 39 mg L-1), and non-volatile suspended solids (NVSS, 18 mg L-1) summer mean concentrations than southern Minnesota lakes (2.1 mg L-1, 14 mg L-1, and 3 mg L-1, respectively). Southern Iowa reservoirs had higher TP (149 μg L-1), TN (1.8 mg L-1), TSS (34 mg L-1), and NVSS (25 mg L-1) summer mean concentrations than northern Missouri reservoirs (47 μg L-1, 0.7 mg L-1, 10 mg L-1, and 7 mg L-1, respectively).
Comparative Limnology of Some Lakes in Interior AlaskaJacqueline D. LaPerriere; Thomas D. Simpson; John R. JonesLake and Reservoir Management1040-23810743-81411922003122 - 132Comparative Limnology of Some Lakes in Interior Alaska Authors: Jacqueline D. LaPerrierea; Thomas D. Simpsona; John R. Jonesb Abstract Fifteen lakes in Interior Alaska (from about 62°N to 64°N and 142°W to 151°W) were sampled on three occasions during the open water season (mid-May to early September) in either 1993 or 1994. Lakes varied in elevation from 218 to 1124 m, in area from 33 to 6303 ha and in maximum depth from 4 to 49 m. Deep lakes thermally stratified during summer with lake cooling and destratification in some by August. Lakes with mean depth of <5 m were polymictic during summer. Anoxia was measured at depth in the most fertile lakes, and metalimnetic oxygen maxima in several lakes were associated with conditions favoring sub-surface algal peaks. There were near equal numbers of clear and stained lakes. One lake was eutrophic and the others were either oligo-or mesotrophic. About half the lakes had TN:TP < 11 by weight, indicating a regional potential for N-limitation. Among Interior lakes, salinity, as measured by conductivity and alkalinity was correlated with TN and TP which fits with the long-recognized pattern between parent geology and nutrients. These data are compared with previous lake studies in the Interior. Keywords: freshwater; nutrients; chlorophyll; water clarity; Alaska View Full Text ArticleSubscribe Affiliations: a Alaska Cooperative Fish and Wildlife Research Unit, University of Alaska Fairbanks, Fairbanks, AK b Department of Fisheries and Wildlife Sciences, University of Missouri, Columbia, MO DOI: 10.1080/07438140309354078 Published in: Lake and Reservoir Management, Volume 19, Issue 2 June 2003 , pages 122 - 132 Publication Frequency: 4 issues per year First Published on: 01 June 2003 Formats available: PDF (English) Fifteen lakes in Interior Alaska (from about 62°N to 64°N and 142°W to 151°W) were sampled on three occasions during the open water season (mid-May to early September) in either 1993 or 1994. Lakes varied in elevation from 218 to 1124 m, in area from 33 to 6303 ha and in maximum depth from 4 to 49 m. Deep lakes thermally stratified during summer with lake cooling and destratification in some by August. Lakes with mean depth of <5 m were polymictic during summer. Anoxia was measured at depth in the most fertile lakes, and metalimnetic oxygen maxima in several lakes were associated with conditions favoring sub-surface algal peaks. There were near equal numbers of clear and stained lakes. One lake was eutrophic and the others were either oligo-or mesotrophic. About half the lakes had TN:TP < 11 by weight, indicating a regional potential for N-limitation. Among Interior lakes, salinity, as measured by conductivity and alkalinity was correlated with TN and TP which fits with the long-recognized pattern between parent geology and nutrients. These data are compared with previous lake studies in the Interior.
PrefaceJack JonesLake and Reservoir Management1040-23810743-81411922003iiiPreface Author: Jack Jonesa View Full Text ArticleSubscribe Affiliation: a University of Missouri, DOI: 10.1080/07438140309354075 Published in: Lake and Reservoir Management, Volume 19, Issue 2 June 2003 , page iii Publication Frequency: 4 issues per year First Published on: 01 June 2003 Formats available: PDF (English)
Limnology of Harding Lake, Alaska: A Deep, Subarctic LakeJacqueline D. LaPerriereLake and Reservoir Management1040-23810743-8141192200393 - 107Limnology of Harding Lake, Alaska: A Deep, Subarctic Lake Author: Jacqueline D. LaPerrierea Abstract Harding Lake (mean depth =16 m) located in Interior Alaska (64°25'N, 146°50'W), studied in the early 1970s in response to concerns about the impact of lakeshore development on water quality was sampled again in summer 1993 thereby providing comparative data over a 20-year period. The lake is usually dimictic but some years stratification begins under the ice and the lake misses a re-oxgenating overturn. One-third of the annual heat budget of about 19,600 cal cm2 is taken up by melting the ice cover. The lake is the common calcium-bicarbonate type but is dilute due to its relatively small watershed and dominance of siliceous material in the local lithography. Based on Secchi transparency, plant nutrients and algal chlorophyll the lake is oligotrophic, with no evidence the lake has been enriched during the study period. Annual primary productivity was estimated at 48 C m2 yr-1 and exhibited a seasonal pulse that began in early May and reached peak values just before ice-off at the end of May. Two chironomid species were identified that were indicative of oligotrophic conditions in this Nearctic lake. Data on vascular plant biomass and zooplankton are presented. Keywords: nearctic lake; nitrogen; phosphorus; phytoplankton; water clarity; thermal stratification View Full Text ArticleSubscribe Affiliation: a Alaska Cooperative Fish and Wildlife Research Unit, Biological Resources Division, U.S. Geological Survey, University of Alaska Fairbanks, Fairbanks, AK DOI: 10.1080/07438140309354076 Published in: Lake and Reservoir Management, Volume 19, Issue 2 June 2003 , pages 93 - 107 Publication Frequency: 4 issues per year First Published on: 01 June 2003 Formats available: Harding Lake (mean depth =16 m) located in Interior Alaska (64°25'N, 146°50'W), studied in the early 1970s in response to concerns about the impact of lakeshore development on water quality was sampled again in summer 1993 thereby providing comparative data over a 20-year period. The lake is usually dimictic but some years stratification begins under the ice and the lake misses a re-oxgenating overturn. One-third of the annual heat budget of about 19,600 cal cm2 is taken up by melting the ice cover. The lake is the common calcium-bicarbonate type but is dilute due to its relatively small watershed and dominance of siliceous material in the local lithography. Based on Secchi transparency, plant nutrients and algal chlorophyll the lake is oligotrophic, with no evidence the lake has been enriched during the study period. Annual primary productivity was estimated at 48 C m2 yr-1 and exhibited a seasonal pulse that began in early May and reached peak values just before ice-off at the end of May. Two chironomid species were identified that were indicative of oligotrophic conditions in this Nearctic lake. Data on vascular plant biomass and zooplankton are presented.
Limnology of Lakes in Gates of the Arctic National Park and Preserve, AlaskaJacqueline D. LaPerriere; John R. Jones; David K. SwansonLake and Reservoir Management1040-23810743-81411922003108 - 121Limnology of Lakes in Gates of the Arctic National Park and Preserve, Alaska Authors: Jacqueline D. LaPerrierea; John R. Jonesb; David K. Swansonc Abstract Limnological reconnaissance data were collected during summers 1992-93 and 1995 from 16 major lakes within Gates of the Arctic National Park and Preserve, Alaska (GAAR) located above the Arctic Circle. In GAAR the southern lakes (~67°N) and those in the Brooks Range foothills are in watersheds with taiga and tundra vegetation. The northern lakes (~68°N) are at higher elevations in the Brooks Range in watersheds that lie wholly beyond the treeline. Average sum of the cations for all lakes matches the world average for fresh waters and the average for drainage from tundra and taiga landscapes. Local lithography explains the measured decrease in calcium equivalents and silica, and an increase in magnesium with altitude because of more calcareous rock in the southern basins at low altitude and shale/conglomerate in northern mountain catchments. In most low altitude lakes Secchi depth was located in sub-surface algal peaks at temperatures averaging ~8.5 C cooler than the surface, typically with double the surface chlorophyll value. Mineral turbidity, and less so color, controlled transparency in several high altitude lakes where turbid inflows were a factor. Lakes were oligotrophic based on nutrients and algal chlorophylli, but a doubling of TP and concurrent halving of TN was measured in GAAR lakes with altitude. Both patterns were correlated with the decreasing density of terrestrial vegetation with altitude, resulting in a sharp decline in the TN:TP ratio. This pattern suggests sources of these nutrients change across the landscape continuum within GAAR described by altitude and vegetation zones. Nitrogen fixation associated with terrestrial vegetation most likely accounts for greater TN in lakes within the taiga and moist or wet tundra, whereas TN levels approximated the N content of regional rainfall in high elevation lakes with predominately barren land and prostrate shrub in the catchments. Ratios of TN:TP and Nutrient Stimulation Bioassays suggest P limitation was likely among low altitude lakes and N limitation increased in importance in lakes at high altitude. The particulate composition ratio (as C:N:P molar ratio) of these lakes averaged ~200:20:1. Keywords: arctic lake; mountain lake; nitrogen; phosphorus; phytoplankton; water clarity View Full Text ArticleSubscribe Affiliations: a Alaska Cooperative Fish and Wildlife Research Unit, University of Alaska Fairbanks, Fairbanks, AK b Department of Fisheries and Wildlife Sciences, University of Missouri, Columbia, MO c Department of Plant, Animal and Soil Sciences, University of Alaska Fairbanks, Fairbanks, AK DOI: 10.1080/07438140309354077 Published in: Lake and Reservoir Management, Volume 19, Issue 2 June 2003 , pages 108 - 121 Publication Frequency: 4 issues per year First Published on: 01 June 2003 Formats available: Limnological reconnaissance data were collected during summers 1992-93 and 1995 from 16 major lakes within Gates of the Arctic National Park and Preserve, Alaska (GAAR) located above the Arctic Circle. In GAAR the southern lakes (~67°N) and those in the Brooks Range foothills are in watersheds with taiga and tundra vegetation. The northern lakes (~68°N) are at higher elevations in the Brooks Range in watersheds that lie wholly beyond the treeline. Average sum of the cations for all lakes matches the world average for fresh waters and the average for drainage from tundra and taiga landscapes. Local lithography explains the measured decrease in calcium equivalents and silica, and an increase in magnesium with altitude because of more calcareous rock in the southern basins at low altitude and shale/conglomerate in northern mountain catchments. In most low altitude lakes Secchi depth was located in sub-surface algal peaks at temperatures averaging ~8.5 C cooler than the surface, typically with double the surface chlorophyll value. Mineral turbidity, and less so color, controlled transparency in several high altitude lakes where turbid inflows were a factor. Lakes were oligotrophic based on nutrients and algal chlorophylli, but a doubling of TP and concurrent halving of TN was measured in GAAR lakes with altitude. Both patterns were correlated with the decreasing density of terrestrial vegetation with altitude, resulting in a sharp decline in the TN:TP ratio. This pattern suggests sources of these nutrients change across the landscape continuum within GAAR described by altitude and vegetation zones. Nitrogen fixation associated with terrestrial vegetation most likely accounts for greater TN in lakes within the taiga and moist or wet tundra, whereas TN levels approximated the N content of regional rainfall in high elevation lakes with predominately barren land and prostrate shrub in the catchments. Ratios of TN:TP and Nutrient Stimulation Bioassays suggest P limitation was likely among low altitude lakes and N limitation increased in importance in lakes at high altitude. The particulate composition ratio (as C:N:P molar ratio) of these lakes averaged ~200:20:1.
Connectivity Influences Temporal Variation of Limnological Conditions in Missouri River Scour LakesMatthew F. Knowlton; John R. JonesLake and Reservoir Management1040-23810743-81411922003160 - 170Connectivity Influences Temporal Variation of Limnological Conditions in Missouri River Scour Lakes Authors: Matthew F. Knowltona; John R. Jonesa Abstract Two scour lakes in the Missouri River floodplain were sampled 20 months (April 1996 - December 1997) to examine effects of river inflow on mixing, seston, and nutrient dynamics. Lake NC-11 (≈4 ha) is deep (≈16 m), sheltered, dimictic, and connected to the river only during floods. Lake S-19 (≈20 ha) comprises two sub-basins, a deep (≈12 m) riverine forewater perennially connected to the river and a shallow (≈4 m), polymictic backwater of variable connectivity. Stratification in NC-11 affected, and was affected by, river inputs - cool inflows mixed completely and sometimes destratified the lake, warmer inflows were partly or completely confined to the epilimnion. Mixing between basins at S-19 was incomplete except during floods. During floods, concentrations of seston and particulate N and P were similar in the two basins of S-19, but conditions in the two basins diverged substantially during inter-flood periods as lower water levels reduced lateral exchange. Seston concentrations in NC-11 during floods were much less (≈90% less) than in S-19 or the river. In NC-11, algal blooms (chlorophyll 50-90 μg L-1) occurred in summer post-flood periods, but larger blooms (chlorophyll 50-256 μg L-1) occurred in the S-19 backwater during periods of low connectivity in all seasons. Nitrate-N peaked at >2 mg L-1 during floods but was exhausted during algal blooms along with up to ≈90% of dissolved phosphorus. Silica declined sharply (up to 93%) in many, but not all blooms, but remained >0.5 mg L-1 in all observations. Connectivity influenced many lake features and enhanced nutrient availability, but other floodplain lakes lacking river connections have similar algal biomass. Keywords: Missouri River; floodplain lakes; scour basins; nutrients; chlorophyll; suspended solids; connectivity; 1993 flood View Full Text ArticleSubscribe Affiliation: a Department of Fisheries and Wildlife Sciences, University of Missouri, Columbia, MO DOI: 10.1080/07438140309354082 Published in: Lake and Reservoir Management, Volume 19, Issue 2 June 2003 , pages 160 - 170 Publication Frequency: 4 issues per year First Published on: 01 June 2003 Formats available: Two scour lakes in the Missouri River floodplain were sampled 20 months (April 1996 - December 1997) to examine effects of river inflow on mixing, seston, and nutrient dynamics. Lake NC-11 (≈4 ha) is deep (≈16 m), sheltered, dimictic, and connected to the river only during floods. Lake S-19 (≈20 ha) comprises two sub-basins, a deep (≈12 m) riverine forewater perennially connected to the river and a shallow (≈4 m), polymictic backwater of variable connectivity. Stratification in NC-11 affected, and was affected by, river inputs - cool inflows mixed completely and sometimes destratified the lake, warmer inflows were partly or completely confined to the epilimnion. Mixing between basins at S-19 was incomplete except during floods. During floods, concentrations of seston and particulate N and P were similar in the two basins of S-19, but conditions in the two basins diverged substantially during inter-flood periods as lower water levels reduced lateral exchange. Seston concentrations in NC-11 during floods were much less (≈90% less) than in S-19 or the river. In NC-11, algal blooms (chlorophyll 50-90 μg L-1) occurred in summer post-flood periods, but larger blooms (chlorophyll 50-256 μg L-1) occurred in the S-19 backwater during periods of low connectivity in all seasons. Nitrate-N peaked at >2 mg L-1 during floods but was exhausted during algal blooms along with up to ≈90% of dissolved phosphorus. Silica declined sharply (up to 93%) in many, but not all blooms, but remained >0.5 mg L-1 in all observations. Connectivity influenced many lake features and enhanced nutrient availability, but other floodplain lakes lacking river connections have similar algal biomass.
Fecal Bacteria, Nutrients, Chlorophyll, and Dissolved Oxygen in a Constructed Habitat Wetland Receiving Treated Municipal Effluent and River WaterMatthew F. Knowlton; John R. JonesLake and Reservoir Management1040-23810743-81411922003171 - 183Fecal Bacteria, Nutrients, Chlorophyll, and Dissolved Oxygen in a Constructed Habitat Wetland Receiving Treated Municipal Effluent and River Water Authors: Matthew F. Knowltona; John R. Jonesa Abstract The Eagle Bluffs Conservation Area (Eagle Bluffs) in central Missouri includes about 400 ha of floodable pools and channels managed as seasonal or permanent habitat wetlands using treated municipal effluent from the Columbia Wastewater Treatment Wetland. Effluent, which is used year around, provides about half the annual water input and is supplemented during waterfowl migrations by pumping from the adjacent Missouri River. Infiltration rates are high (≈900 cm yr-1) because of high soil permeability. Water quality of inflows and selected pools and channels on Eagle Bluffs has been monitored since wetland flooding began in 1994 because of concerns about possible negative effects of wastewater and interest in the dynamics of nutrients and algal biomass in the system. Compared to river water, effluent typically had high concentrations of fecal bacteria, chloride, dissolved phosphorus, and dissolved nitrogen, especially ammonia-N. In the water Distribution Channel (DC) and terminal wetland pools of Eagle Bluffs fecal bacteria decline rapidly and are usually within the range suitable for human water contact (<200 cells 100 mL-1). Phosphorus and nitrogen concentrations vary with the relative inputs of effluent and river water and in situ losses. On the basis of comparison with chloride concentrations, over half of incoming phosphorus and nitrogen are lost from surface water to sediments, plant uptake or denitrification. Nutrient losses from the large proportion of water lost to infiltration are not known. Chlorophyll concentrations in the DC and wetland pools exceeded 100 μg L-1 in 35% of observations, but chlorophyll and organic matter concentrations on Eagle Bluffs are similar to those in Missouri River oxbow lakes with much lower nutrient inputs. Ammonia concentration frequently exceed USEPA acute and chronic toxicity criteria, but fish seem to thrive on Eagle Bluffs. Overall, negative effects of effluent use seem minimal with respect to intended uses of the habitat wetland, but effects of infiltrating effluent on subsurface drinking water supplies are still in question. Keywords: habitat wetland; wastewater; Missouri River; nutrients; fecal bacteria; chloride; chlorophyll; dissolved oxygen View Full Text ArticleSubscribe Affiliation: a Department of Fisheries and Wildlife Sciences, University of Missouri, Columbia, MO, USA DOI: 10.1080/07438140309354083 Published in: Lake and Reservoir Management, Volume 19, Issue 2 June 2003 , pages 171 - 183 Publication Frequency: 4 issues per year First Published on: 01 June 2003 Formats available: The Eagle Bluffs Conservation Area (Eagle Bluffs) in central Missouri includes about 400 ha of floodable pools and channels managed as seasonal or permanent habitat wetlands using treated municipal effluent from the Columbia Wastewater Treatment Wetland. Effluent, which is used year around, provides about half the annual water input and is supplemented during waterfowl migrations by pumping from the adjacent Missouri River. Infiltration rates are high (≈900 cm yr-1) because of high soil permeability. Water quality of inflows and selected pools and channels on Eagle Bluffs has been monitored since wetland flooding began in 1994 because of concerns about possible negative effects of wastewater and interest in the dynamics of nutrients and algal biomass in the system. Compared to river water, effluent typically had high concentrations of fecal bacteria, chloride, dissolved phosphorus, and dissolved nitrogen, especially ammonia-N. In the water Distribution Channel (DC) and terminal wetland pools of Eagle Bluffs fecal bacteria decline rapidly and are usually within the range suitable for human water contact (<200 cells 100 mL-1). Phosphorus and nitrogen concentrations vary with the relative inputs of effluent and river water and in situ losses. On the basis of comparison with chloride concentrations, over half of incoming phosphorus and nitrogen are lost from surface water to sediments, plant uptake or denitrification. Nutrient losses from the large proportion of water lost to infiltration are not known. Chlorophyll concentrations in the DC and wetland pools exceeded 100 μg L-1 in 35% of observations, but chlorophyll and organic matter concentrations on Eagle Bluffs are similar to those in Missouri River oxbow lakes with much lower nutrient inputs. Ammonia concentration frequently exceed USEPA acute and chronic toxicity criteria, but fish seem to thrive on Eagle Bluffs. Overall, negative effects of effluent use seem minimal with respect to intended uses of the habitat wetland, but effects of infiltrating effluent on subsurface drinking water supplies are still in question.
The Use of a Pattern Judgement Model to Assess Fish Habitat Suitability in Two Colorado ReservoirsEric P. Bergersen; Patrick J. MartinezLake and Reservoir Management1040-23810743-8141191200355 - 78The Use of a Pattern Judgement Model to Assess Fish Habitat Suitability in Two Colorado Reservoirs Authors: Eric P. Bergersena; Patrick J. Martinezb Abstract The suitability of two Colorado reservoirs to support an array of common fish species was assessed using a pattern judgement model. The model employs an expert panel to predict habitat suitability based on easily measured structural characteristics of the reservoir basin, local site climate, operational regime, and inflow characteristics. Model predictions, made before Kenney Reservoir was filled, indicated mat common carp (Cyprinus carpio) and black crappie (Pomoxis nigromaculatus) would dominate the fish community in this reservoir. Sampling in the decade following completion of the dam substantiated this prediction. When additional species were added to the model and their likely performance in Kenney Reservoir evaluated, predictions offish community composition closely followed trends observed in reservoir species composition. A proposed enlargement of an existing reservoir was evaluated with the model to predict what species might prosper as a result of the new configuration of the reservoir basin and inundation of new land areas. None of the 10 species evaluated were predicted to flourish in the new habitat provided by the enlargement. Predictions were consistent with the low abundance of these species in the existing reservoir and the probable lack of suitable habitat in the enlargement area. The pattern judgement model can be used to explore management options dealing with probable species performance as a function of the quality of available habitat using relatively static data garnered at low cost. The model's flexibility allows modification of input variable values to reflect local conditions or specific needs without altering model logic. Guidance is provided for adding more species to the model to broaden its applicability to other waters. Keywords: reservoir fish habitat; pattern judgement model View Full Text ArticleSubscribe Affiliations: a Colorado Cooperative Fish and Wildlife Research Unit, Colorado State University, Fort Collins, Colorado b Colorado Division of Wildlife, Grand Junction, Colorado DOI: 10.1080/07438140309353989 Published in: Lake and Reservoir Management Publication Frequency: 4 issues per year First Published on: 01 March 2003 Formats available: PDF (English) The suitability of two Colorado reservoirs to support an array of common fish species was assessed using a pattern judgement model. The model employs an expert panel to predict habitat suitability based on easily measured structural characteristics of the reservoir basin, local site climate, operational regime, and inflow characteristics. Model predictions, made before Kenney Reservoir was filled, indicated mat common carp (Cyprinus carpio) and black crappie (Pomoxis nigromaculatus) would dominate the fish community in this reservoir. Sampling in the decade following completion of the dam substantiated this prediction. When additional species were added to the model and their likely performance in Kenney Reservoir evaluated, predictions offish community composition closely followed trends observed in reservoir species composition. A proposed enlargement of an existing reservoir was evaluated with the model to predict what species might prosper as a result of the new configuration of the reservoir basin and inundation of new land areas. None of the 10 species evaluated were predicted to flourish in the new habitat provided by the enlargement. Predictions were consistent with the low abundance of these species in the existing reservoir and the probable lack of suitable habitat in the enlargement area. The pattern judgement model can be used to explore management options dealing with probable species performance as a function of the quality of available habitat using relatively static data garnered at low cost. The model's flexibility allows modification of input variable values to reflect local conditions or specific needs without altering model logic. Guidance is provided for adding more species to the model to broaden its applicability to other waters.
The Sounds of Silence: Trends in the Regulation of Personal WatercraftTamara A. DudiakLake and Reservoir Management1040-23810743-8141191200345 - 54The Sounds of Silence: Trends in the Regulation of Personal Watercraft Author: Tamara A. Dudiaka Abstract In recent years, U.S. courts have upheld arguably objectionable local ordinances that single out particular kinds of vessels such as the personal watercraft. Communities across the country have grown bolder in recent years as congestion on U.S. waters increases and state enabling legislation becomes more specific in terms of the watercraft to be regulated, the zoning tools to be employed, and the objectives to be achieved. Standard police power objectives, which form the basis for boating regulations, are now articulated not only in terms of protecting public health, safety and welfare, but in terms of protecting the environment, encouraging historical uses, and preserving peace and tranquility. The purpose of this paper is to provide an overview of boating regulatory authority and watercraft specific regulations as well as discuss and offer an analysis of recent key court decisions and trends in personal watercraft regulation. Courts have been reluctant to question the judgment of local government and will uphold a regulation provided certain basic elements are present. That these local regulations have been upheld is indicative of a greater judicial responsiveness to ordinances whose primary objective is not simply public welfare and safety, but more specifically the protection of natural resources and environmental integrity. Keywords: personal watercraft; boating regulations; boating ordinances; surface use management View Full Text ArticleSubscribe Affiliation: a College of Natural Resources, Stevens Point, WI DOI: 10.1080/07438140309353988 Published in: Lake and Reservoir Management, Volume 19, Issue 1 March 2003 , pages 45 - 54 Publication Frequency: 4 issues per year First Published on: 01 March 2003 Formats available: In recent years, U.S. courts have upheld arguably objectionable local ordinances that single out particular kinds of vessels such as the personal watercraft. Communities across the country have grown bolder in recent years as congestion on U.S. waters increases and state enabling legislation becomes more specific in terms of the watercraft to be regulated, the zoning tools to be employed, and the objectives to be achieved. Standard police power objectives, which form the basis for boating regulations, are now articulated not only in terms of protecting public health, safety and welfare, but in terms of protecting the environment, encouraging historical uses, and preserving peace and tranquility. The purpose of this paper is to provide an overview of boating regulatory authority and watercraft specific regulations as well as discuss and offer an analysis of recent key court decisions and trends in personal watercraft regulation. Courts have been reluctant to question the judgment of local government and will uphold a regulation provided certain basic elements are present. That these local regulations have been upheld is indicative of a greater judicial responsiveness to ordinances whose primary objective is not simply public welfare and safety, but more specifically the protection of natural resources and environmental integrity.
PrefaceTim AsplundLake and Reservoir Management1040-23810743-81411912003iii - ivPreface Author: Tim Asplunda View Full Text ArticleSubscribe Affiliation: a Wisconsin Department of Natural Resources, Madison, WI, USA DOI: 10.1080/07438140309353983 Published in: Lake and Reservoir Management, Volume 19, Issue 1 March 2003 , pages iii - iv Publication Frequency: 4 issues per year First Published on: 01 March 2003 Formats available:
Development and Application of a Phosphorus Balance Model for Lake Istokpoga, FloridaWilliam W. Walker; Karl E. HavensLake and Reservoir Management1040-23810743-8141191200379 - 91Development and Application of a Phosphorus Balance Model for Lake Istokpoga, Florida Authors: William W. Walker; Karl E. Havensa Abstract Hydrologic and phosphorus (P) mass balance models were constructed for Lake Istokpoga, a large shallow lake in Florida, USA. The objective was to use the models to determine whether there have been long-term trends in the processing of P by this lake, potentially impacting P exports to a downstream ecosystem (Lake Okeechobee). Higher lake P concentrations and outflow loads in recent years appear to be explained by higher runoff. A detailed basin survey will be needed to determine whether changes in land use in the predominantly agricultural and urban watershed also may have contributed to the increased P loads. Lake total P concentrations did not display a significant historical trend, nor did the lake's capacity to assimilate P. A number of statistical approaches are demonstrated that could have general application in establishing nutrient mass balances for lakes with sparse data sets for tributary flows and/or concentrations. Daily simulations of lake phosphorus and chloride levels demonstrate me feasibility of dynamic mass-balance modeling in shallow Florida lakes using simple first-order phosphorus removal kinetics. The model developed here could be used in setting a total maximum daily load (TMDL) for P, once an in-lake concentration goal has been specified. Keywords: Phosphorus; mass balance modeling; Lake Istokpoga; Florida View Full Text ArticleSubscribe Affiliation: a South Florida Water Management District, West Palm Beach, Florida DOI: 10.1080/07438140309353990 Published in: Lake and Reservoir Management, Volume 19, Issue 1 March 2003 , pages 79 - 91 Publication Frequency: 4 issues per year First Published on: 01 March 2003 Formats available: Hydrologic and phosphorus (P) mass balance models were constructed for Lake Istokpoga, a large shallow lake in Florida, USA. The objective was to use the models to determine whether there have been long-term trends in the processing of P by this lake, potentially impacting P exports to a downstream ecosystem (Lake Okeechobee). Higher lake P concentrations and outflow loads in recent years appear to be explained by higher runoff. A detailed basin survey will be needed to determine whether changes in land use in the predominantly agricultural and urban watershed also may have contributed to the increased P loads. Lake total P concentrations did not display a significant historical trend, nor did the lake's capacity to assimilate P. A number of statistical approaches are demonstrated that could have general application in establishing nutrient mass balances for lakes with sparse data sets for tributary flows and/or concentrations. Daily simulations of lake phosphorus and chloride levels demonstrate me feasibility of dynamic mass-balance modeling in shallow Florida lakes using simple first-order phosphorus removal kinetics. The model developed here could be used in setting a total maximum daily load (TMDL) for P, once an in-lake concentration goal has been specified.
Physical Impacts of Wind and Boat Traffic on Clear Lake, Iowa, USAJames L. Anthony; John A. DowningLake and Reservoir Management1040-23810743-814119120031-14Physical Impacts of Wind and Boat Traffic on Clear Lake, Iowa, USA Authors: James L. Anthonyab; John A. Downingc Abstract Clear Lake is a shallow (Zmean=2.9 m), eutrophic (TPmean=188 μgL-1) lake that is intensively used forrecreation. After a century of intense agriculture in the watershed, the bottom is covered with nutrient-rich organic sediments. We monitored wind, boat traffic and turbidity and found that resuspension of this sediment by wind-induced waves and recreational boat traffic contributes to daily, often substantial, nutrient fluxes. Intensive monitoring over a wind-event showed that total phosphorus concentrations can increase by 100% over a diel period and ammonia concentrations increase to levels near to those toxic to fish at the peak of winds. GIS of the digitally analyzed lake basin coupled with physical models show that when wind speeds exceed 10 ms-1 (22 mph), >46% of the lake's benthic surface area may become mobile. Wind speeds >20 ms-1 (44 mph) can mobilize >98% of the lake bottom sediment surface area. The correlation between boat traffic and sediment resuspension was weak (r2 = 0.23) in near-shore monitoring due to confounding by wind and other factors but heavy boat traffic appears to exacerbate wind-induced resuspension and may slow the resettlement of resuspended sedimente. Boat traffic correlated with up to 50% increases in turbidity. Resuspension of sediments by boats is likely to occur across 56% of the lake area. Benthic sediment resuspension may contribute to the suppression of fish and macrophyte communities, domination of the phytoplankton community by Cyanobacteria, suspension of toxic ammonia, and increased restoration time-scales. Keywords: boats; internal loading; nutrients; resuspension; sediment; turbulence; wind View Full Text ArticleSubscribe Affiliations: a Department of Animal Ecology, 124 Science II, Iowa State University, Ames, IA b Department of Environmentl, Population, and Oraganismic Biology, University of Colorado, Boulder, CO c Department of Ecology, Evolution, and Organismal Biology, 124 Science II, Iowa State University, Ames, IA DOI: 10.1080/07438140309353984 Published in: Lake and Reservoir Management, Volume 19, Issue 1 March 2003 , pages 1 - 14 Publication Frequency: 4 issues per year First Published on: 01 March 2003 Formats available: Clear Lake is a shallow (Zmean=2.9 m), eutrophic (TPmean=188 μgL-1) lake that is intensively used forrecreation. After a century of intense agriculture in the watershed, the bottom is covered with nutrient-rich organic sediments. We monitored wind, boat traffic and turbidity and found that resuspension of this sediment by wind-induced waves and recreational boat traffic contributes to daily, often substantial, nutrient fluxes. Intensive monitoring over a wind-event showed that total phosphorus concentrations can increase by 100% over a diel period and ammonia concentrations increase to levels near to those toxic to fish at the peak of winds. GIS of the digitally analyzed lake basin coupled with physical models show that when wind speeds exceed 10 ms-1 (22 mph), >46% of the lake's benthic surface area may become mobile. Wind speeds >20 ms-1 (44 mph) can mobilize >98% of the lake bottom sediment surface area. The correlation between boat traffic and sediment resuspension was weak (r2 = 0.23) in near-shore monitoring due to confounding by wind and other factors but heavy boat traffic appears to exacerbate wind-induced resuspension and may slow the resettlement of resuspended sedimente. Boat traffic correlated with up to 50% increases in turbidity. Resuspension of sediments by boats is likely to occur across 56% of the lake area. Benthic sediment resuspension may contribute to the suppression of fish and macrophyte communities, domination of the phytoplankton community by Cyanobacteria, suspension of toxic ammonia, and increased restoration time-scales.
Stirring up Trouble? Resuspension of Bottom Sediments by Recreational WatercraftM. M. Beachler; D. F. HillLake and Reservoir Management1040-23810743-8141191200315 - 25Stirring up Trouble? Resuspension of Bottom Sediments by Recreational Watercraft Authors: M. M. Beachlera; D. F. Hilla Abstract An experimental and theoretical study of the hydrodynamic impacts of recreational watercraft in shallow water bodies is presented. Of particular interest is the ability of turbulent prop or jet wash to resuspend bottom sediments. Intuition suggests, and the experiments confirm, that this ability is a strong function of boat speed and water depth. The results of this study demonstrate that boats operating at high speed have no greater impact on the lake bed than boats travelling at idle speeds. The greatest impact is seen when boats are travelling at 'near-plane' speeds. This critical speed is a function of boat size and water depth. To increase the usefulness of the observations, a theoretical model of the flow underneath a passing boat was developed and validated with the data. Relying on only a few input parameters, the model can be used to estimate, for example, the minimum operating depth required for a given boat to prevent sediment resuspension. Discussion of the relevance of this work in the context of setting use restrictions for watercraft is provided. Keywords: boating; recreational conflicts; sediment resuspension; hydrodynamics View Full Text ArticleSubscribe Affiliation: a Department of Civil and Environmental Engineering, The Pennsylvania State University, University Park, PA DOI: 10.1080/07438140309353985 Published in: Lake and Reservoir Management, Volume 19, Issue 1 March 2003 , pages 15 - 25 Publication Frequency: 4 issues per year First Published on: 01 March 2003 Formats available: An experimental and theoretical study of the hydrodynamic impacts of recreational watercraft in shallow water bodies is presented. Of particular interest is the ability of turbulent prop or jet wash to resuspend bottom sediments. Intuition suggests, and the experiments confirm, that this ability is a strong function of boat speed and water depth. The results of this study demonstrate that boats operating at high speed have no greater impact on the lake bed than boats travelling at idle speeds. The greatest impact is seen when boats are travelling at 'near-plane' speeds. This critical speed is a function of boat size and water depth. To increase the usefulness of the observations, a theoretical model of the flow underneath a passing boat was developed and validated with the data. Relying on only a few input parameters, the model can be used to estimate, for example, the minimum operating depth required for a given boat to prevent sediment resuspension. Discussion of the relevance of this work in the context of setting use restrictions for watercraft is provided.
Managing Recreational Use on the Yahara LakesSusan A. JonesLake and Reservoir Management1040-23810743-8141191200335 - 44Managing Recreational Use on the Yahara Lakes Author: Susan A. Jonesa Abstract Conflict between water recreation users is a universal problem that is likely to become worse. Dane County, located in southern Wisconsin, has experienced growth in recreational use and increased perception of user conflict that mirror national trends. The Yahara River chain of lakes includes the County's four largest lakes, which provide more than 7400 ha (18,000 acres) of water easily accessible to residents of this, the fastest growing county in Wisconsin. This paper describes and evaluates Dane County's experiences with, and strategies for balancing the interests of increasing number of different activities using the same resources. Users have identified wakes from other boats, lack of courtesy, excessive speed, crowding, and inconsiderate behavior as problems. Dane County's recreation management efforts described in the paper include a200-ft(61 m)slow-no-wake regulation, coupled with state boating safety and equipment rules. Educational initiatives include formal boater safety education classes, and outreach materials and maps developed by the Dane County Lakes and Watershed Commission. Future management efforts need to solicit input from all types of recreational users, focus educational efforts on recreational use impacts on aquatic ecosystems as well as the regulations themselves, and use a deliberate planning process that could resolve recreational conflicts and bring about balanced resource use. Keywords: Yahara River; water recreation management; boating regulations; boater education; user conflicts; Dane County; Dane County Lakes and Watershed Commission; Wisconsin View Full Text ArticleSubscribe Affiliation: a Dane County Lakes and Watershed Commission, Madison, WI, USA DOI: 10.1080/07438140309353987 Published in: Lake and Reservoir Management, Volume 19, Issue 1 March 2003 , pages 35 - 44 Publication Frequency: 4 issues per year First Published on: 01 March 2003 Formats available: PDF (English) Conflict between water recreation users is a universal problem that is likely to become worse. Dane County, located in southern Wisconsin, has experienced growth in recreational use and increased perception of user conflict that mirror national trends. The Yahara River chain of lakes includes the County's four largest lakes, which provide more than 7400 ha (18,000 acres) of water easily accessible to residents of this, the fastest growing county in Wisconsin. This paper describes and evaluates Dane County's experiences with, and strategies for balancing the interests of increasing number of different activities using the same resources. Users have identified wakes from other boats, lack of courtesy, excessive speed, crowding, and inconsiderate behavior as problems. Dane County's recreation management efforts described in the paper include a200-ft(61 m)slow-no-wake regulation, coupled with state boating safety and equipment rules. Educational initiatives include formal boater safety education classes, and outreach materials and maps developed by the Dane County Lakes and Watershed Commission. Future management efforts need to solicit input from all types of recreational users, focus educational efforts on recreational use impacts on aquatic ecosystems as well as the regulations themselves, and use a deliberate planning process that could resolve recreational conflicts and bring about balanced resource use.
Personal Watercraft and Boats: Coastal Conflicts With Common TernsJoanna BurgerLake and Reservoir Management1040-23810743-8141191200326 - 34Personal Watercraft and Boats: Coastal Conflicts With Common Terns Author: Joanna Burgera Abstract Human disturbance to nesting colonial birds has increased with the massive development of coastal regions and rapid improvement in technology of watercraft. Disturbance to nesting common terns (Sterna hirundo) by boats was examined over a five-year period, with different degrees of management of personal watercraft (PWC) activities. In the five years before this study, reproductive success had declined to zero, perhaps due to excessive personal watercraft activity. Terns responded with significantly more upflights to PWCs that raced by and circled the island, than to motor boats that travelled slowly and remained in the channel. Public meetings and an educational campaign were successful in decreasing the percent of PWCs that raced and ran around die island, which in turn decreased die number of tern upflights and increased reproductive success. Without continued public meetings and education, PWCs began to race around the island, and the terns responded by moving from island edges to central areas that were lower and vulnerable to tidal flooding. In the following year, designated areas for rental PWC use were established, which again decreased the PWC traffic, allowing the birds to nest on the island edges. All management practices increased reproductive success, but a combination of education, public meetings, increased signage, enforcement, and designated zones for PWCs resulted in the greatest increase in reproductive success. Involving stakeholders in the process allowed people and birds to coexist, but continued vigilance and public education were essential to successful management. Keywords: disturbance; terns; personal watercraft; boats; coastal; conservation; co-management View Full Text ArticleSubscribe Affiliation: a Division of Life Sciences and Consortium for Risk Evaluation with Stakeholder Participation, Environmental and Occupational Health Sciences Institute, Rutgers University, Piscataway, NJ DOI: 10.1080/07438140309353986 Published in: Lake and Reservoir Management, Volume 19, Issue 1 March 2003 , pages 26 - 34 Publication Frequency: 4 issues per year First Published on: 01 March 2003 Formats available: Human disturbance to nesting colonial birds has increased with the massive development of coastal regions and rapid improvement in technology of watercraft. Disturbance to nesting common terns (Sterna hirundo) by boats was examined over a five-year period, with different degrees of management of personal watercraft (PWC) activities. In the five years before this study, reproductive success had declined to zero, perhaps due to excessive personal watercraft activity. Terns responded with significantly more upflights to PWCs that raced by and circled the island, than to motor boats that travelled slowly and remained in the channel. Public meetings and an educational campaign were successful in decreasing the percent of PWCs that raced and ran around die island, which in turn decreased die number of tern upflights and increased reproductive success. Without continued public meetings and education, PWCs began to race around the island, and the terns responded by moving from island edges to central areas that were lower and vulnerable to tidal flooding. In the following year, designated areas for rental PWC use were established, which again decreased the PWC traffic, allowing the birds to nest on the island edges. All management practices increased reproductive success, but a combination of education, public meetings, increased signage, enforcement, and designated zones for PWCs resulted in the greatest increase in reproductive success. Involving stakeholders in the process allowed people and birds to coexist, but continued vigilance and public education were essential to successful management.
Trophic State, Seasonal Patterns and Empirical Models in South Korean ReservoirsJohn R. Jones; Matthew F. Knowlton; Kwang-Guk AnLake and Reservoir Management1040-23810743-8141191200364 - 78Trophic State, Seasonal Patterns and Empirical Models in South Korean Reservoirs Authors: John R. Jonesa; Matthew F. Knowltona; Kwang-Guk Anb Abstract Data from 59 reservoirs in South Korea, sampled monthly during 1993-2000, showed that about one-third were mesotrophic, nearly one-half were eutrophic and the remainder were hypereutrophic based on conventional criteria for total phosphorus (TP), chlorophyll (Chi) and Secchi depth. Most reservoirs had >1 mg L-1 total nitrogen (TN) resulting in high mass ratios of TN:TP (range 23 to 243, median 76) relative to many temperate lakes. To compensate, conventional TN criteria were provisionally adjusted upward by about 2.5-times to classify Korean reservoirs uniformly across all trophicstate metrics. During die summer monsoon, TP and TN typically peaked in mesotrophic reservoirs and declined in the hypereutrophic group. The inference is that monsoon inflow produces these patterns by increasing non-point external inputs mat dominate the nutrient budgets of mesotrophic reservoirs while diluting point-source inputs important in hypereutrophic impoundments. Eutrophic reservoirs showed both response patterns, so that taken in aggregate a seasonal response was not apparent. The log relation between Chl and TP was linear and showed an average yield of Chl per unit of TP on par with other temperate lakes. Seasonally, die Chl-TP relation was strongest during summer and weaker during fall-winter which is consistent with increased light-limitation during mixis in these monomictic impoundments. Seasonal development of Chl did not show strong evidence of a spring or fail bloom. About half of the time maximum Chl values were measured during the monsoon or post-monsoon (July-September). Maximum Chl was ~3 times the annual mean and during summer maximum Chl was ~ double the mean. The log relation between Chl and Secchi depth matched mat found in North American lakes and the seasonal phenology for Secchi depth was die opposite of Chl and suspended solids. The analysis confirms that die monsoon is a major source of variation within and among Korean reservoirs. Keywords: Korea; trophic state; monsoon; nutrients; chlorophyll; transparency; seasonal patterns View Full Text ArticleSubscribe Affiliations: a Department of Fisheries and Wildlife Sciences, University of Missouri, Columbia, MO b Department of Environmental Science and Engineering, Ewha Womans University, Seoul, Republic of Korea DOI: 10.1080/07438140309353991 Published in: Lake and Reservoir Management, Volume 19, Issue 1 March 2003 , pages 64 - 78 Publication Frequency: 4 issues per year First Published on: 01 March 2003 Formats available: PDF (English) Data from 59 reservoirs in South Korea, sampled monthly during 1993-2000, showed that about one-third were mesotrophic, nearly one-half were eutrophic and the remainder were hypereutrophic based on conventional criteria for total phosphorus (TP), chlorophyll (Chi) and Secchi depth. Most reservoirs had >1 mg L-1 total nitrogen (TN) resulting in high mass ratios of TN:TP (range 23 to 243, median 76) relative to many temperate lakes. To compensate, conventional TN criteria were provisionally adjusted upward by about 2.5-times to classify Korean reservoirs uniformly across all trophicstate metrics. During die summer monsoon, TP and TN typically peaked in mesotrophic reservoirs and declined in the hypereutrophic group. The inference is that monsoon inflow produces these patterns by increasing non-point external inputs mat dominate the nutrient budgets of mesotrophic reservoirs while diluting point-source inputs important in hypereutrophic impoundments. Eutrophic reservoirs showed both response patterns, so that taken in aggregate a seasonal response was not apparent. The log relation between Chl and TP was linear and showed an average yield of Chl per unit of TP on par with other temperate lakes. Seasonally, die Chl-TP relation was strongest during summer and weaker during fall-winter which is consistent with increased light-limitation during mixis in these monomictic impoundments. Seasonal development of Chl did not show strong evidence of a spring or fail bloom. About half of the time maximum Chl values were measured during the monsoon or post-monsoon (July-September). Maximum Chl was ~3 times the annual mean and during summer maximum Chl was ~ double the mean. The log relation between Chl and Secchi depth matched mat found in North American lakes and the seasonal phenology for Secchi depth was die opposite of Chl and suspended solids. The analysis confirms that die monsoon is a major source of variation within and among Korean reservoirs.
Development and Application of Hydrologic Restoration Goals for a Large Subtropical LakeKarl E. HavensLake and Reservoir Management1040-23810743-81411842002285 - 292Development and Application of Hydrologic Restoration Goals for a Large Subtropical Lake Author: Karl E. Havensa Abstract During planning for the Comprehensive Everglades Restoration Program (CERP), ecosystem conceptual models were used to develop hydrologic restoration goals for Lake Okeechobee, a large multi-purpose lake at the center of the regional ecosystem. The models were based on observational and experimental research, and the goals were used to evaluate alternative restoration plans. Results were integrated with those from several other parts of the regional system. A best overall plan was selected, and the United States Congress authorized the CERP in 2000. In Lake Okeechobee, the CERP is expected to reduce the occurrence of damaging high and low water levels, and increase the occurrence of spring water level recessions that benefit native biota. Ecosystem conceptual models will continue to be and used as a framework for long-term adaptive assessment during CERP implementation. The overall approach represents an effective integration of science and resource management. Keywords: lake restoration; ecosystem conceptual models; hydrologic goals View Full Text ArticleSubscribe Affiliation: a South Florida Water Management District, West Palm Beach, Florida, USA DOI: 10.1080/07438140209353934 Published in: Lake and Reservoir Management Publication Frequency: 4 issues per year First Published on: 01 December 2002 Formats available: During planning for the Comprehensive Everglades Restoration Program (CERP), ecosystem conceptual models were used to develop hydrologic restoration goals for Lake Okeechobee, a large multi-purpose lake at the center of the regional ecosystem. The models were based on observational and experimental research, and the goals were used to evaluate alternative restoration plans. Results were integrated with those from several other parts of the regional system. A best overall plan was selected, and the United States Congress authorized the CERP in 2000. In Lake Okeechobee, the CERP is expected to reduce the occurrence of damaging high and low water levels, and increase the occurrence of spring water level recessions that benefit native biota. Ecosystem conceptual models will continue to be and used as a framework for long-term adaptive assessment during CERP implementation. The overall approach represents an effective integration of science and resource management.
Water-level Management as a Tool for the Restoration of Shallow Lakes in the NetherlandsHugo Coops; S. Harry HosperLake and Reservoir Management1040-23810743-81411842002293 - 298Water-level Management as a Tool for the Restoration of Shallow Lakes in the Netherlands Authors: Hugo Coopsa; S. Harry Hospera Abstract Water-level fluctuations are among the major driving forces for shallow lake ecosystems. In the low-lying parts of the Netherlands, the water-level regime of lakes is strictly regulated. This is needed for reducing risks of flooding and economic purposes, including maximum agricultural benefit. The fixation of water levels has had a severe impact on the functioning of (semi-)aquatic ecosystems. We review the benefits of natural water-level fluctuations, considering the impacts on nutrient inputs, nutrient concentrations, phytoplankton development and turbidity. In particular, the mediating role of submersed and emergent vegetation and filter feeders is addressed. The present government policy, to allow more space for water, presents a major challenge for combining flood prevention measures and ecological restoration. Restoration of natural water-level regimes, which is likely to lead to enhancement of water quality and biodiversity, may occur in two ways: (1) expanding the critical limits between which the water level is allowed to fluctuate annually, and/or (2) incidental recessions of the water level. It is stressed that ecologically-based water-level regimes should be incorporated into the context of multiple use of lakes. Keywords: lake restoration; water-level fluctuations; water management View Full Text ArticleSubscribe Affiliation: a RIZA, AA Lelystad, the Netherlands DOI: 10.1080/07438140209353935 Published in: Lake and Reservoir Management, Volume 18, Issue 4 December 2002 , pages 293 - 298 Publication Frequency: 4 issues per year First Published on: 01 December 2002 Formats available: Water-level fluctuations are among the major driving forces for shallow lake ecosystems. In the low-lying parts of the Netherlands, the water-level regime of lakes is strictly regulated. This is needed for reducing risks of flooding and economic purposes, including maximum agricultural benefit. The fixation of water levels has had a severe impact on the functioning of (semi-)aquatic ecosystems. We review the benefits of natural water-level fluctuations, considering the impacts on nutrient inputs, nutrient concentrations, phytoplankton development and turbidity. In particular, the mediating role of submersed and emergent vegetation and filter feeders is addressed. The present government policy, to allow more space for water, presents a major challenge for combining flood prevention measures and ecological restoration. Restoration of natural water-level regimes, which is likely to lead to enhancement of water quality and biodiversity, may occur in two ways: (1) expanding the critical limits between which the water level is allowed to fluctuate annually, and/or (2) incidental recessions of the water level. It is stressed that ecologically-based water-level regimes should be incorporated into the context of multiple use of lakes.
Linking Science with Management of Freshwater SystemsKarl E. HavensLake and Reservoir Management1040-23810743-81411842002iii
Setting Flow Levels for Controlling Cyanobacterial Blooms in Tropical Weir PoolsMyriam Bormans; Phillip FordLake and Reservoir Management1040-23810743-81411842002275 - 284Setting Flow Levels for Controlling Cyanobacterial Blooms in Tropical Weir Pools Toxic cyanobacterial blooms occur frequently in water supply weir pools and storages in tropical Australia and elsewhere. They flourish under warm stratified conditions and their amelioration and management is an ongoing problem. We investigated bloom occurrence and growth in 3 separate water storages on the Fitzroy River in Queensland, Australia. We show that there is an opportunity to reduce its prevalence by manipulation of the riverine flow to remove the stratification, and to raise the turbidity through the resuspension of the finely divided bottom sediments. These effects are not due solely to flushing the weirs but to “resetting” the optical and mixing depths so that conditions are inimical to buoyant cyanobacteria. The persistence of the sediment particles in the water column, and the size of the discharge are the two most important factors in determining the effectiveness of the procedure.
Managing Taste and Odor Problems in a Eutrophic Drinking Water ReservoirVal H. Smith; Jonathan Sieber-Denlinger; Frank deNoyelles Jr.; Scott Campbell; Shugen Pan; Stephen J. Randtke; Gerald T. Blain; Vernon A. StrasserLake and Reservoir Management1040-23810743-81411842002319 - 323Managing Taste and Odor Problems in a Eutrophic Drinking Water Reservoir Drinking water for the City of Wichita, KS is provided by Cheney Reservoir, a eutrophic impoundment constructed by the U.S. Bureau of Reclamation in 1962. This large, shallow reservoir has a mean depth of 5.3 meters and a surface area of 40 km2. Numerous reports of undesirable taste and odor in drinking water were received by the City of Wichita Water and Sewer Department in the early 1990's, and periodic episodes of objectionable tastes and odor have occurred up through fall 2001. An intensive limnological sampling program was carried out from August 1999-October 2000, and simultaneous measurements of two taste and odor-causing compounds (geosmin and methylisoborneol) in the lakewater were also performed. These data were used to construct empirical, phosphorus-based water quality management recommendations designed to help reduce the likelihood of objectionable taste and odor events in Cheney Reservoir. The general framework developed here should also be applicable to other waterbodies exhibiting taste and odor-related problems.
Growth of Calcareous Epilithic Mats in the Margin of Natural and Polluted Hydrosystems: Phosphorus Removal Implications in the C–111 Basin, Florida Everglades, USASerge Thomas; Evelyn E. Gaiser; Miroslav Gantar; Aga Pinowska; Leonard J. Scinto; Ronald D. JonesLake and Reservoir Management1040-23810743-81411842002324 - 330Growth of Calcareous Epilithic Mats in the Margin of Natural and Polluted Hydrosystems: Phosphorus Removal Implications in the C-111 Basin, Florida Everglades, USA The Florida Everglades is a fragile wetland system that is naturally depleted in phosphorus (P). This hydrosystem has been heavily impacted by human activities, including the draining of wetlands to provide water for agricultural and urban use. The result is a highly compartmentalized system with altered hydropatterns; wetlands receive canal discharges from diffuse agricultural/urban runoff containing high levels of pollutants, including P. Excess loading of P has induced ecological changes, including dramatic effects on periphyton, the dominant producer community. An Everglades rehabilitation plan has been established to restore natural hydropatterns and decrease P loads. On the southern edge of a large canal (C-111) draining the southern Everglades, levees have been removed to rehabilitate hydrology in the adjacent marsh. Levee removal resulted in exposure of limestone bedrock that, when flooded with shallow water from the canal, favors the development of thick calcareous epilithic mats. When flooded approximately 6 months a year, this margin area between the polluted and the natural hydrosystem functions as a Periphyton-based Stormwater Treatment Area(PSTA), a biological tool developed at the Southeast Environmental Research Center (Miami, FL), being considered in the Everglades as a means of P removal from enriched waters. Here, we evaluate the harvesting rates of periphyton that promote the most efficient removal of TP from the water entering the marsh. Results indicate that harvesting of periphyton at 3 month intervals provides the greatest TP sequestration.
Quantification of Oxygen Depletion in Lakes and Reservoirs with the Hypoxic FactorGertrud K. NürnbergLake and Reservoir Management1040-23810743-81411842002299 - 306Quantification of Oxygen Depletion in Lakes and Reservoirs with the Hypoxic Factor The amount of dissolved oxygen (DO) in lake water has biological and chemical implications. There are no easy ways to quantify exeedences of important thresholds of DO in lakes, except the complete lack of DO, quantified as an annual or seasonal anoxic factor (Nrnberg 1995a, b). Here an analogous concept, the “Hypoxic Factor” (HF) is introduced. According to specific water quality standards, certain levels of oxygen depletion can be quantified, e.g., DO concentrations below 5 mg L-1 or 6.5 mg L-1. The HF is computed from the duration and extent of hypoxia by using DO profiles and hypsographic data. It is expressed in such a way that a value of 365 d yr-1 would mean the whole lake has a DO concentration below the specified level at all times. The application to a TMDL project, where DO standards are to be employed in a large Snake River reservoir, demonstrates the potential usefulness of HF. This quantification of hypoxia allows the testing of hypotheses, e.g., the dependency of hypoxia on stage height, flow and nutrients. Significant relationships were found between annual expressions of hypoxia and hydrological variables (seasonal flows, water retention time) and a climatic index.
Watershed Impacts of Logging and Wildfire: Case Studies in CanadaBernadette Pinel-Alloul; Ellie Prepas; Dolors Planas; Robert Steedman; Théo CharetteLake and Reservoir Management1040-23810743-81411842002307 - 318Watershed Impacts of Logging and Wildfire: Case Studies in Canada In Canada, disturbance of boreal forests has increased due to expanding anthropogenic activities, particularly forestry. A first attempt was made to evaluate impacts of forest harvesting and wildfire on changes in water quality and biota of lakes. We present case studies in two major geological and climatic subregions of the boreal ecozone in Canada: the Boreal Plain and the Boreal Shield. Responses of lake ecosystems to wildfire and logging differed. In upland Boreal Plain lakes, total phosphorus (P), inorganic nitrogen (N) and algal biomass were higher in lakes with burned watersheds, whereas, only total P increased in lakes with watershed logging. Logging on the Boreal Shield and wildfire in wetland-and permafrost-dominated watersheds on the northern Boreal Plain were associated with increases in dissolved organic carbon (DOC) and water colour, possibly causing light-limitation of algae in both regions, and a decrease in calanoid biomass in eastern Boreal Shield lakes. The number of water quality indicators affected by watershed disturbances was greater in the oligotrophic ecosystems of the Boreal Shield. The nutrient response of disturbed lakes was strongly related to lake drainage ratios: lakes with high drainage ratios had the strongest response to disturbance. Effects were also dependent on climate, wetland coverage, and regional lake characteristics. Morphometric, chemical, and biological indicators are recommended to monitor natural and anthropogenic watershed disturbances of aquatic ecosystems in Canada's Boreal forest.
Development of a Total Phosphorus Concentration Goal in the TMDL Process for Lake Okeechobee, Florida (USA)Karl E. Havens; William W. Walker Jr.Lake and Reservoir Management1040-23810743-81411832002227 - 238Development of a Total Phosphorus Concentration Goal in the TMDL Process for Lake Okeechobee, Florida (USA) This paper describes the approach used to establish an in-lake concentration goal for total phosphorus in the total maximum daily load (TMDL) process carried out by die Florida Department of Environmental Protection (FDEP) for Lake Okeechobee. In order to specify the in-lake phosphorus goal, the first consideration was to identify the most suitable indicator of “imbalance in flora or fauna” pursuant to Subsection 62-302.530(48)(b) of the Florida Administrative Code (FAC). Blooms of cyanobacteria (blue-green algae) were previously identified as one of the most serious symptoms of cultural eutrophication in this lake, and there existed a large data set relating total phosphorus to chlorophyll a, which can be used to index the occurrence of blooms. We evaluated the occurrence of samples with chlorophyll a in excess of 40 μg·L-1 (moderate bloom) and 60 μg·L-1 (severe bloom) as a function of total phosphorus concentrations in order to specify the lake phosphorus goal. A cross-tabulation procedure was used to identify a range of total phosphorus corresponding to a rapid increase in bloom frequency. Near-shore and pelagic data sets were sorted by total phosphorus and each was sub-divided into ten intervals of approximately equal sample size. When total phosphorus averaged below 30 μg·L-1, the probability of moderate blooms was below 3% and the probability of severe blooms was near 1% in the near-shore region. When total phosphorus averaged between 35 and 45 μg·L-1, frequencies were between 15 and 35% for moderate blooms and between 2 and 5% for severe blooms, respectively. Pelagic bloom frequencies also increased with increasing phosphorus, but the response was considerably muted relative to that observed in the near-shore area. To ensure an acceptable level of risk in terms of algal bloom occurrence, a total phosphorus goal of 40 μg·L-1 was selected by the FDEP. Mass-balance modeling results (Walker 2000) indicate that an average external phosphorus load of 140 metric tons y1 (compared to a 1973 to 1999 mean of 498 metric tons y1) would provide a long-term average phosphorus concentration in the lake's pelagic zone of 40 μg·L-1. Based on our empirical model relating bloom frequencies to total phosphorus, it is predicted that under these TMDL loading conditions, bloom frequencies in the near-shore region would be 2 to 9%, as compared to 5 to 33% under present conditions. Successful implementation of the TDML should significantly reduce near-shore bloom frequencies in Lake Okeechobee.
Trophic Changes in Otsego Lake, NY Following the Introduction of the Alewife (Alosa psuedoharengus)Willard N. Harman; Matthew F. Albright; David M. WarnerLake and Reservoir Management1040-23810743-81411832002215 - 226Trophic Changes in Otsego Lake, NY Following the Introduction of the Alewife (Alosa psuedoharengus) Changes at several trophic levels in Otsego Lake from the 1930s to present are described relative to changes in the planktivorous fish community. Prior to the late 1980s, cisco (Coregonus artedi) was the dominant planktivore. The alewife (Alosa pseudoharengus) appeared in 1986 and subsequently became dominant. Two patterns emerged when we contrasted the pelagic flora and fauna under those two dominant planktivore populations. When cisco were the primary planktivores, cladoceran size and biomass was significantly greater in the epilimnion (primarily Daphnia pulex) than in the hypolimnion (primarily Bosmina coregoni). Phytoplankton were dominated by net and large nannoplankton (>0.03 mm), withcyano bacteria uncommon until late summer. From 1973-1988, mean summer chlorophyll a was 2.3±1.2 (S.D.) μg·L-1 (range 0.68-4.2). Mean summer Secchi transparency was 5.2 ± 0.5 m (range 3.8-7.8). Areal hypolimnetic oxygen deficits (AHOD; a measure of oxygen consumption during periods of stratification) were 0.076-0.080 mg cm-2 day-1. Since alewife have dominated, Daphnia have become rare in the lake. Mean cladoceran size in the epilimnion and hypolimnion (essentially all Bosmina) is much more uniform and reduced from prior size distributions. Phytoplankton abundance has increased, as has the mean summer chlorophyll a (6.4 ±1.5 S.D ug·L-1, range 3-8.7). The dominant algae are now smaller nannoplankton (< 0.03 mm) and cyanobacteria. Mean summer Secchi transparency decreased substantially to 3.2 ± 0.3 m (range 2.5-4.0) and AHOD increased (range 0.090-0.102 mg cm-2 day1). Whitefish (Coregonus clupeaformis) and cisco have declined, while lake trout (Salvelinus namycush)have increased. All changes have occurred despite significant efforts to reduce non-point source nutrient loading to the lake. While the establishment of alewives has enhanced the production of Otsego Lake's salmonid fishery to date, it has increased the challenge to those interested in managing the lake in an ecologically sustainable manner.
Movements of Displaced Largemouth Bass in Two Indiana Natural LakesJed PearsonLake and Reservoir Management1040-23810743-81411832002257 - 262Movements of Displaced Largemouth Bass in Two Indiana Natural Lakes Movements of largemouth bass Micropterus salmoides that were displaced within and between two inter-connected natural lakes in Indiana were monitored to determine if they would return to their capture locations. Nine largemouth bass were captured by angling and electro fishing at Lake Wawasee and surgically fitted with ultrasonic transmitters. Five bass (experimentals) were then displaced 3.1-8.1 km downstream into Syracuse Lake. For comparison, four bass (controls) were released in Lake Wawasee, two displaced (2.4 and 3.6 km) and two released at their capture sites. Locations of bass were determined over a 15-month period. Only one experimental bass returned to Lake Wawasee and the area where it was captured. One experimental bass was removed from the channel between the lakes by an angler, another bass failed to return and either died or shed its transmitter in Syracuse Lake, and two experimental bass were last located within Syracuse Lake before contact was lost. The two control bass displaced within Lake Wawasee returned to their capture areas, while the two control bass released at their capture sites remained in those vicinities and moved shorter distances than displaced fish. Experimental fish were tracked during 11-348 d, compared to 77-452 d for control fish, possibly reflecting greater survival of the latter. The results of this study should encourage largemouth bass tournament organizers and fishery managers to adopt measures to reduce inter-lake displacement of angler-caught fish.
Limnological and Statistical Issues for Monitoring the Impact of a Lake Source Cooling Facility: Cayuga Lake, NYDavid A. Matthews; Stephen V. Stehman; Steven W. EfflerLake and Reservoir Management1040-23810743-81411832002239 - 256Limnological and Statistical Issues for Monitoring the Impact of a Lake Source Cooling Facility: Cayuga Lake, NY Limnological data collected for two years at nine sites in the southern end of Cayuga Lake, NY, before the start-up of a cooling water facility (summer 2000), are analyzed to identify appropriate measures of trophic state and estimate the capability of a monitoring program to identify changes associated with the operation of this facility. The concentration of chlorophyll a (Chl) is found to be the preferred indicator of trophic state. The concentration of total phosphorus and clarity are compromised as trophic indicators in this system because of the contributions of inanimate particles (tripton) to these measures associated with the hydrology and morphometry of the lake and the occurrence of the whiting phenomenon. A Before-After-Control-Impact design is used to assess the ability of the monitoring program to detect potential impacts associated with operation of the cooling water facility. Statistical power analyses conducted with the preoperational monitoring data indicate the current bi-weekly sampling program will detect a 30% change in Chl with a probability of 0.7. Attributing causation of any future change in Chi coincident with the start-up and operation of the cooling water facility is problematic because of potential confounding effects associated with variation in phosphorus loading from wastewater treatment facilities, natural variation in meteorological conditions, and water quality changes associated with zebra mussel populations.
Whole Lake Fluridone Treatments For Selective Control of Eurasian Watermilfoil: I. Application Strategy and Herbicide ResiduesKurt D. Getsinger; John D. Madsen; Tyler J. Koschnick; Michael D. NetherlandLake and Reservoir Management1040-23810743-81411832002181 - 190Whole Lake Fluridone Treatments For Selective Control of Eurasian Watermilfoil: I. Application Strategy and Herbicide Residues The herbicide fluridone is being used in northern lakes and reservoirs to control the exotic species Eurasian watermilfoil (Myriophyllumspicatum L.). Since quantitative information linking changes in plant communities following fluridone applications is limited, particularly with respect to water residue records, a study was conducted to investigate the effect of low-dose treatments on the submersed plant communities in four Michigan lakes. The overall study objective was to determine whether plant species diversity and frequency of occurrence were affected by low-dose fluridone applications in the year of treatment. The primary objective of this portion of the overall study was to provide an application strategy that would maintain a threshold dose of fluridone, 5 μg·L-1 declining to 2 μg·L-1, in the treated lakes to selectively control Eurasian watermilfoil. Study lakes were 55 to 220 ha in size and contained an average of nine species of submersed plants. Big Crooked, Camp, Lobdell, and Wolverine lakes were treated in mid-May 1997 with the formulation Sonar® AS, to yield an initial concentration of 5 μg·L-1 fluridone in the upper 3.05 m of each lake. Asequential application of Sonar® AS was conducted on each lake at 16 to 21 days after initial treatment (DAIT), intended to reestablish a fluridone concentration of 5 μg·L-1 in the upper 3.05 m of each lake. Bass, Big Seven, Clear, and Heron lakes received no fluridone applications and served as untreated reference sites. Water residue samples were collected at prescribed intervals on each fluridone-treated lake from pretreatment up to 81 DAIT. Samples were collected from six littoral stations and from two deep locations throughout each lake, and temperature profiles were measured at the deep stations. Fluridone residues were analyzed using two separate techniques, the newly developed enzyme-linked immunosorbent assay and the standard high performance liquid chromatography method. Fluridone levels on three of the treated lakes met the laboratory-derived criteria for achieving good control of Eurasian watermilfoil by providing a peak concentration of approximately 5 μg·L-1 during the first 2 weeks posttreatment, and by main taininga concentration >2 μg·L-1 through 60 DAIT. Residues became well mixed in the water column under isothermal conditions, and thermal stratification prevented mixing of fluridone into deeper and colder waters. Residue data indicated that thermal stratification, or the lack thereof, at the time of herbicide application can affect target herbicide concentrations. Using the volume of a pre-selected depth zones to calculate the amount of fluridone needed to achieve a particular target concentration can result in an over- or under-dosing of a water body.
Reservoir Zones: Microbial Production and Trophic StateOwen T. LindLake and Reservoir Management1040-23810743-81411832002263 - 271Reservoir Zones: Microbial Production and Trophic State It is hypothesized that differences in the trophic states of three reservoir zones - riverine, transition, and lacustrine; i.e., change through space, can provide insights into the general eutrophication of the system; i.e., change through time. Differences in phyto-and bacterioplankton dynamics among the zones of reservoirs are explored. Microbial dynamics described for the eutrophication of natural lakes are taken as a null hypothesis against which reservoir zones are compared. Factors capable of affecting microbial community composition, production, metabolism and biomass accumulation are evaluated in the different zones. The lack of sufficient reservoir data on microbial processes, and particularly those of the bacterioplankton, prevents the shaping of comprehensive reservoir zone microbial models. The hypotheses posed provide a guide for much-needed reservoir research.
Sedimentological Effects of Aeration-Induced Lake CirculationDaniel R. Engstrom; David I. WrightLake and Reservoir Management1040-23810743-81411832002201 - 214Sedimentological Effects of Aeration-Induced Lake Circulation Multiple sediment cores were collected from each of ten Minnesota lakes (five aerated and five non-aerated) to evaluate the long-term effects of aeration-induced circulation on sediment accumulation and composition. Coring sites for each basin were widely spaced at different depths to encompass a range of depositional environments, and sediments were dated by 210Pb methods. All lakes, aerated and non-aerated, show an increase in sediment accumulation commencing around the time of European settlement in the region (c. 1880). At the same time, sedimentary organic content decreases by 5-40% in all but three lakes due to increased inputs of silts and clays from erosion of catchment soils. Sediment accumulation rates do not decline with the onset of aeration in any of the aerated lakes, but in most cases remain near maximum values to the present day. A recent decrease in sediment flux, evident in one non-aerated lake, was driven by land-use changes in the catchment that decreased nutrient and sediment loading. Sedimentary organic content does not decline in any of the lakes, aerated or non-aerated, during the last two decades. Historic patterns of sediment accumulation and composition in the aerated lakes are no different from that shown by non-aerated lakes. Results from this study do not support claims that aeration-induced circulation will enhance the removal of organic sediments from lake basins either by mineralization or offshore transport.
Whole Lake Fluridone Treatments For Selective Control of Eurasian Watermilfoil: II. Impacts on Submersed Plant CommunitiesJohn D. Madsen; Kurt D. Getsinger; R. Michael Stewart; Chetta S. OwensLake and Reservoir Management1040-23810743-81411832002191 - 200Whole Lake Fluridone Treatments For Selective Control of Eurasian Watermilfoil: II. Impacts on Submersed Plant Communities The aquatic herbicide fluridone is being used in northern tier states to selectively control the submersed exotic species Eurasian watermilfoil (Myriophyllum spicatum L.) growing in lakes and reservoirs. Reliable quantitative information linking changes in the submersed plant community following fluridone applications is limited, particularly with respect to water residue records. Therefore, a study was conducted to investigate the effect of low-dose fluridone treatments on the submersed plant communities in four lakes in Michigan. The overall study objective was to determine whether submersed plant species diversity and frequency were impacted by low-dose fluridone applications in the year of treatment, when targeting a whole lake for Eurasian watermilfoil control. The primary objectives of this portion (part II) of the overall study was to determine fluridone effectiveness on the exotic submersed species Eurasian watermilfoil (Myriophyllum spicatum L.) and to evaluate shifts in plant species diversity at one year posttreatment. Secondary objectives included determining fluridone effectiveness on the exotic submersed species curlyleaf pondweed (Potamogeton crispus L.) and verifying laboratory-derived results of fluridone concentration and exposure time relationships with respect to efficacy against Eurasian watermilfoil. Quantitative sampling of vegetation was performed using point-based frequency of species occurrence to evaluate whole-lake distribution and diversity of the submersed plant community of all eight study lakes. The technique was implemented using global positioning and geographic information systems, with a minimum grid resolution of 50 m by 50 m. Plant surveys were conducted in early to mid May and in mid August in 1997 (year of treatment) and 1998 (12 and 15 months post treatment). The fluridone concentration and exposure time (CET) relationship resulted in good to excellent control of Eurasian watermilfoil through 15 months posttreatment on three of the treated lakes (Big Crooked, Camp, and Lobdell). On a fourth lake, Wolverine, the required CET relationship was not maintained and poor control of Eurasian water milfoil was observed. There was no strong evidence of long-term curlyleaf pondweed control in any of the fluridone-treated lakes. The herbicide application strategy used in this study did not significantly impact the native plant species diversity or cover in the year of treatment, or through 15 months posttreatment, in any of the fluridone-treated lakes. Native plant cover was maintained at levels >70% in the year of treatment and at one year posttreatment; a level above the range (20 to 40%) recommended for healthy fish and wildlife habitat. The selective control of Eurasian watermilfoil achieved in this study verified results from previously conducted laboratory and outdoor mesocosm evaluations.
Trophic State Differences in Population Characteristics of Gizzard Shad in Two Tennessee River ImpoundmentsDarien L. Clayton; Michael J. MaceinaLake and Reservoir Management1040-23810743-81411822002109 - 117Trophic State Differences in Population Characteristics of Gizzard Shad in Two Tennessee River Impoundments Gizzard shad Dorosoma cepedianum population characteristics, including relative abundance, size structure, growth, body condition, and mortality were compared between Guntersville and Wheeler Reservoirs, two Tennessee River impoundments. Fish were collected with DC electrofishing and water quality was sampled along upstream to downstream longitudinal gradients in each reservoir from October 1995 through August 1996. Chlorophyll-a concentrations and gizzard shad abundance were higher in Wheeler than in Guntersville Reservoir. Neither chlorophyll-a concentrations nor gizzard shad a bundances showed a longitudinal gradient from upstream to downstream in either reservoir. However, a gradient of increasing water clarity was evident in both reservoirs that was associated with poorer gizzard shad body condition. In Guntersville Reservoir, where gizzard shad abundance was lower, the population was comprised of older and larger fish that exhibited faster growth and higher body condition. Gizzard shad were more abundant in Wheeler Reservoir, and fish displayed slower growth, poorer body condition, and potentially greater exposure time to predation. Hence, survival was lower as this population was comprised of a higher proportion of younger fish than in Guntersville Reservoir. Trophic state differences among reservoirs were related to differences in gizzard shad population characteristics and likely influenced the role of these fish as a prey species.
Development of a Fish Contaminant Monitoring Protocol for Lake Mead, NevadaShawn L. Gerstenberger; Barbara EcclestonLake and Reservoir Management1040-23810743-81411822002118 - 128Development of a Fish Contaminant Monitoring Protocol for Lake Mead, Nevada Fish consumption practices and patterns for Lake Mead, Nevada, were determined by administering detailed questionnaires to 150 sportsmen at the Lake Mead National Recreation Area. Striped bass, largemouth bass and channel catfish were the most frequently consumed fish species, with an average of 22 ± 3.6 fish meals a year consumed by respondents. Striped bass and largemouth bass between 13-18 inches were most commonly consumed, while channel catfish were typically between 10-15 inches in length. Skin-off fillets of all three species was the preferred method of preparation, while cooking techniques varied by species. The most popular fishing areas in our survey included Government Wash, Hemenway Harbor, Overton Beach, Saddle Cove, St. Thomas and the Las Vegas Bay (wash). Based on these data, a three fish, four location contaminant monitoring protocol was developed to best represent human exposure to contaminated fish at Lake Mead. This sampling design is applicable to large lakes and reservoirs where succinct toxicological data are needed, but standard sampling techniques would be excessively expensive or impractical.
Influence of a Reservoir Drawdown on Bird Use of Lake Talquin, FloridaGary L. Sprandel; Richard L. Cailteux; David T. CobbLake and Reservoir Management1040-23810743-81411822002164 - 176Influence of a Reservoir Drawdown on Bird Use of Lake Talquin, Florida We examined the effects of a reservoir drawdown on avian use of Lake Talquin in the Florida Panhandle. Observations during the drawdown of 1998 showed increased wading bird, larid, and passerine bird usage of the lake. A decline in the number of osprey (Pandion haliaetus) nests and mean brood size was also observed during the drawdown. The two years following the drawdown showed increased wading bird usage, non-significant (P > 0.05) change in osprey nest success and young-of-year sport fish numbers, and declining common moorhen (Gallinula chloropus) and lesser scaup (Aythya affinis) use compared to the two years prior to the drawdown. No significant correlation (P > 0.05) was observed between young-of-year sport fish numbers and total wading bird numbers. Post-drawdown changes may have been due to actual biotic changes in the lake, but also may have been part of larger regional or national trends. Lake managers should consider avian species along with the needs of lake front property owners and anglers when implementing a drawdown and refill schedule.
Phytoplankton in Boreal SubArctic Lakes Following Enhanced Phosphorus Loading from Forest Fire: Impacts on Species Richness, Nitrogen and Light LimitationPreston McEachern; Ellie E. Prepas; Dolors PlanasLake and Reservoir Management1040-23810743-81411822002138 - 148Phytoplankton in Boreal SubArctic Lakes Following Enhanced Phosphorus Loading from Forest Fire: Impacts on Species Richness, Nitrogen and Light Limitation Forest fire in peatland environments can cause enhanced loading of coloured compounds and of phosphorus relative to nitrogen resulting in reduced light penetration and nitrogen to phosphorus ratios in lake water. To determine the potential impacts of forest fire in peatland dominated catchments, we tested nitrogen (N), phosphorus (P) and light limitation of pelagic phytoplankton with in situ microcosms in three lakes from a Boreal SubArctic ecozone. To assess if phytoplankton assemblages were influenced by water chemistry changes following fire, phytoplankton species were identified from 10 lakes in unburnt and 10 lakes in burnt catchments. In the microcosm study, P limitation and concurrent N + P limitation of phytoplankton biomass were apparent (P « 0.01) in the two lake waters representing the range of N and P concentrations for lakes in unburnt catchments. In the lake with water representative of lakes in burnt catchments, nitrogen limitation was observed (P « 0.01). Light limitation of phytoplankton biomass was observed in microcosms from one lake in a burnt and one lake from an unburnt catchment likely due to high water colour in both lake waters (> 200 mg/L [Pt]). For the 20 surveyed lakes, phytoplankton species richness was 36% lower (P « 0.01) in lakes from burnt compared to unburnt catchments. Phytoplankton communities in all lakes in this study were dominated by cyanobacteria. Phytoplankton communities in boreal forest lakes may be particularly sensitive to catchment disturbances such as fire because changes in phosphorus and carbon loading from peatlands enhance nitrogen and light limitation.
Phosphorus Budget and Management Strategies for an Urban Wisconsin LakeWilliam F. James; John W. Barko; Harry L. Eakin; Patrick W. SorgeLake and Reservoir Management1040-23810743-81411822002149 - 163Phosphorus Budget and Management Strategies for an Urban Wisconsin Lake Multiple external and internal phosphorus (P) sources to an urban lake, Half Moon Lake in Wisconsin, were examined during the summer of 1999 in order to develop management strategies for effective P control and reversal of eutrophication (Trophic State Index=74). Internal recycling of P accounted for 80% of the summer P budget of the lake. Flux of P from the sediment accounted for most of the internal P loading (42% of total budget). However, decomposition of Potamogeton crispus and recycling of macrophyte P during the middle of the summer growing season, and P resuspension due to motor boat activity, accounted for 20% and 17% of the P budget, respectively, representing additional important sources to be controlled. In contrast, summer P loading via the watershed (storm sewers and precipitation) was much less. Using a water quality model (Bathtub), we found that reduction of internal P sources could substantially reduce by greater than 70% the high concentrations of algae in the lake (mean summer chlorophyll = 82 mg m-3). Suggested internal P control measures included a sediment chemical treatment to bind P, greater harvesting of P. crispus to reduce the macrophyte P pool at the time of senescence, and limiting motor boat activity when the lake is weakly stratified.
Limnological and Loading Information and a Phosphorus Total Maximum Daily Load (TMDL) Analysis for Onondaga LakeSteven W. Effler; Susan M. O'Donnell; David A. Matthews; Carol M. Matthews; David M. O'Donnell; Martin T. Auer; Emmet M. OwensLake and Reservoir Management1040-23810743-8141182200287 - 108Limnological and Loading Information and a Phosphorus Total Maximum Daily Load (TMDL) Analysis for Onondaga Lake The phosphorus (P) total maximum daily load (TMDL) analysis and associated management plan for culturally eutrophic Onondaga Lake, NY, are critically evaluated based on available input/discharge and limnological information for the system. The evaluation is based on: (1) results from a long-term monitoring program conducted on the lake, its tributaries, and the adjoining river that receives the lake's outflow, (2) algal bioassay experiments of the bioavailability of particulate P (PP) in inputs to the lake, (3) loading rate calculations for forms of P in these inputs, (4) calculations of water densities in inflows and the lake, (5) model analyses of plunging interflows and responses to seasonal material loading, and (6) mass balance calculations for a tracer conducted around the lake outlet and the receiving river to estimate inflow to the lake from the river. Several important system-specific characteristics were found not to be accommodated in the current TMDL analysis, including: (1) a P load from the river back into the lake, (2)seasonal plunging of tributaries to depths below the productive layers of the lake, (3) incomplete and different bioavailabilities of PP in the various inputs, (4) the different settling velocities of PP from these sources, (5) false high estimates of TP loading from tributaries associated with turbidity interferences in P analyses, and(6)the implications of the high flushing rate of the lake for strong seasonality in the relative impacts of externals loads. The TMDL analysis is demonstrated to understate the present role of the dominant point source and overstate the importance of non-point sources. Recommendations are made to upgrade the TMDL analysis through an integrated program of model development, testing and application, supporting process studies and monitoring, and re-evaluation of management options.
Reservoir Zones: Microbial Production and Trophic StateOwen T. LindLake and Reservoir Management1040-23810743-81411822002129 - 137Reservoir Zones: Microbial Production and Trophic State It is hypothesized that differences in the trophic states of three reservoir zones - riverine, transition, and lacustrine; i.e., change through space, can provide insights into the general eutrophication of the system; i.e., change through time. Differences in phyto-and bacterioplankton dynamics among the zones of reservoirs are explored. Microbial dynamics described for the eutrophication of natural lakes are taken as a null hypothesis against which reservoir zones are compared. Factors capable of affecting microbial community composition, production, metabolism and biomass accumulation are evaluated in the different zones. The lack of sufficient reservoir data on microbial processes, and particularly those of the bacterioplankton, prevents the shaping of comprehensive reservoir zone microbial models. The hypotheses posed provide a guide for much-needed reservoir research.
Community Responses to Piscivorous Largemouth Bass: A Biomanipulation ExperimentRay W. Drenner; Robert M. Baca; Jeffrey S. Gilroy; Mark R. Ernst; David J. Jensen; David H. MarshallLake and Reservoir Management1040-23810743-8141181200244 - 51Community Responses to Piscivorous Largemouth Bass: A Biomanipulation Experiment To test whether piscivorous largemouth bass (Micropterus salmoides) could be used to biomanipulate a 15-ha water supply reservoir, we assessed the effects of the addition of largemouth bass to the reservoir by monitoring the reservoir during the year before and three years after largemouth bass were stocked. A pilot study conducted in October 1990 indicated that the reservoir was eutrophic and contained a fish community dominated by zooplanktivorous threadfin shad (Dorosoma petenense) and no piscivorous fish. The reservoir was monitored during 1991 prior to stocking of largemouth bass (October 1991) and monitored in 1992, 1993 and 1994 after bass were present. Stocking of largemouth bass was successful and bass spawned in 1992, 1993 and 1994. The effects of bass cascaded down through the food web to the phytoplankton. In 1993 and 1994 the number of threadfin shad decreased, the abundance of cladocerans increased and rotifers decreased. Densities of diatoms and green algae were lower in 1992, 1993 and 1994 than in 1991. Although some phytoplankton densities decreased, blue-green algae, chlorophyll biomass, Secchi transparency, total phosphorus and total nitrogen did not change after stocking of largemouth bass and the biomanipulation was not successful in improving the reservoir's water quality.
Application of a Hypolimnetic Oxygen Profile Model to Lakes in OntarioB. J. Clark; P. J. Dillon; L. A. Molot; H. E. EvansLake and Reservoir Management1040-23810743-8141181200232 - 43Application of a Hypolimnetic Oxygen Profile Model to Lakes in Ontario We tested a previously published empirical multivariate regression model that predicts end-of-summer oxygen concentrations in the hypolimnia of small, dilute lakes in the Boreal ecozone. The model inputs include only lake morphometry and total phosphorus concentration at spring-overturn. In this study, we tested the validity of the model using information for lakes that are larger or deeper, and have higher phosphorus concentrations than the lakes that were the basis for the original regression model. Data from 32 lakes in the Gull River watershed in central Ontario and 10 lakes in eastern Ontario were used to evaluate the model's ability to predict end-of-summer oxygen profiles. Results indicated that the original model was satisfactory for most of the 42 study lakes, but had more limited success in the deeper and larger lakes within the data set. For the eastern Ontario lake set, the original model's ability to predict oxygen in the hypolimnia was better than for the Gull River watershed lakes. It is suggested that the most useful application of the model would be to predict the change in hypolimnetic oxygen concentrations at given depths that would result from increases or decreases in total phosphorus concentrations in the lake. This would allow resource managers concerned with sportfish habitat, to estimate and assess the impact that changes in lake trophic status might have on oxygen concentrations.
Development, Construction, and Use of Lime and Alum Application Systems in Alberta, CanadaMark S. Serediak; Ellie E. Prepas; Tom P. Murphy; Jay BabinLake and Reservoir Management1040-23810743-8141181200266 - 74Development, Construction, and Use of Lime and Alum Application Systems in Alberta, Canada Between 1986 and 1993, a variety of systems, ranging from simple to complex, were designed for lime (slaked lime (Ca(OH)2) or calcite (CaCO3)) and alum (Al2(SO4)3) application to water bodies in Alberta, Canada. Application systems were used both experimentally, to determine the effectiveness of lime and alum in reducing phosphorus and algae, and commercially, for the treatment of water bodies with excessive algal and/or macrophyte growth. System designs ranged from inexpensive, easy to assemble but labour-intensive prototype models, to commercially viable, low-labour requirement systems, capable of applying chemicals to aquatic systems ranging in size from small water bodies (about 300 m2) to medium-sized lakes (about 75 ha). Results of these projects suggest that, while all systems were effective for the treatment of problem algae and macrophytes, local conditions, efficiency, and cost must determine each system's usefulness.
Response of an Aquatic Macrophyte Community to Fluctuating Water Levels in an Oligotrophic LakeTyler Wagner; C. Michael FalterLake and Reservoir Management1040-23810743-8141181200252 - 65Response of an Aquatic Macrophyte Community to Fluctuating Water Levels in an Oligotrophic Lake This study compares the species composition, biomass, and the influence of substrate composition on an aquatic macrophyte community in the meso-oligotrophic Lake Pend Oreille, Idaho under two winter drawdown regimes. Mean dry aquatic macrophyte biomass (AMB) in the drawdown zone (1.4 - 3.5 m) significantly increased from 39.9 gm-2 in 1990 to 99.2 gm-2 and 103.7 gm-2 with 2.1 m drawdowns in 1998 and 1999. Mean AMB deeper than 3.5 m did not significantly increase, suggesting the increased biomass in the drawdown zone can at least partially be attributed to increased winter survival. Myriophyllum sibiricum, Chara spp., and Potamogeton richardsonii were the most abundant aquatic macrophytes under the 3.5 m winter drawdown regime, while Chara spp., P berchtoldii, and P. crispus were most abundant under higher winter water levels. The exotic M. spicatum was present at one sample station and most prevalent in depths between 3.9 - 5.1 m. M. spicatum attained mean maximum densities in excess of 900 gm-2 by August, 1999 (one year after it was first observed in the lake). Logistic regression indicated a higher probability of finding clay and cobble substrates in the drawdown zone. On the clay substrates, there were significantly lower AMB (17.9 gm-2) than on sand (86.6 gm-2) or silt (129.0 gm-2) substrata with no plants observed on gravel or cobble substrata.
Application of the Two-Dimensional Hydrothermal and Water Quality Model, CE-QUAL-W2, to the Chesapeake Bay – Conowingo ReservoirPatrick N. Deliman; Jeffrey A. GeraldLake and Reservoir Management1040-23810743-8141181200210-19Application of the Two-Dimensional Hydrothermal and Water Quality Model, CE-QUAL-W2, to the Chesapeake Bay - Conowingo Reservoir The application of the two-dimensional hydrothermal and water quality model, CE-QUAL-W2, to the Conowingo Reservoir is presented. The performance of the CE-QUAL-W2 model was enhanced with the addition of multiple particle size settling rates, and an algorithm to account for the scour process within a reservoir. The benefit of the Conowingo Reservoir to perform sediment and nutrient trapping was determined from the calculation of removal efficiencies which showed important characteristics for this reservoir which is near the end of its useful lifespan in regards to trapping capability.
Volunteer Lake Monitoring: Testing the Reliability of Data Collected by the Florida LAKEWATCH ProgramDaniel E. Canfield Jr.; Claude D. Brown; Roger W. Bachmann; Mark V. HoyerLake and Reservoir Management1040-23810743-814118120021-9Volunteer Lake Monitoring: Testing the Reliability of Data Collected by the Florida LAKEWATCH Program Because the use of volunteer samplers is a very cost-effective way to collect large amounts of information on lakes over space and time, we studied the reliability of the protocols used by the Florida LAKEWATCH program. We found that chlorophyll extractions with hot ethanol gave values that were no different from those obtained with the standard method of grinding with acetone. In a comparative study of 125 lakes we found the data collected by volunteers were comparable to those collected by professionals. Mean Secchi disk depth, TP, TN, and chlorophyll values obtained by the citizens were strongly correlated (r > 0.99) to the mean values obtained by the professionals. To determine if freezing was a valid means of preserving water samples prior to analysis, we compared estimates of chlorophyll, TP, TN, pH, total alkalinity, and specific conductance obtained from fresh samples with estimates obtained from samples frozen up to 150 days. For most lakes there was little difference in chemical measurements made in samples preserved by freezing for different lengths of time, and various statistical tests indicated that freezing was a valid means of preserving lake water samples prior to analysis. Water quality data produced by volunteer samplers following the LAKEWATCH protocols were just as good as those from samples collected by professional biologists and handled using standard methods of sample preservation. The fact that volunteers can collect credible data means that lake management agencies could amplify their limited budgets by using volunteer monitoring, to sample more lakes and to sample them more frequently.
Comparison of Immunoassay and HPLC for Analyzing Fluridone Concentrations: New Applications for Immunoassay TechniquesMichael D. Netherland; David R. Honnell; Alicia G. Staddon; Kurt D. GetsingerLake and Reservoir Management1040-23810743-8141181200275 - 80Comparison of Immunoassay and HPLC for Analyzing Fluridone Concentrations: New Applications for Immunoassay Techniques High performance liquid chromatography (HPLC) and an enzyme-linked immunosorbent assay (ELISA) technique were used to analyze concentrations of the aquatic herbicide fluridone (l-methyl-3 phenyl-5-[-3 (trifluromethyl) phenyl]-4 (IH) pyridinone) in 488 surface water samples collected from two lakes in Michigan treated in 1997, 2 Michigan lakes treated in 1998, 1 lake in Florida treated in 1996, and a series of research ponds treated in Florida in 1997. Samples were collected following application of fluridone associated with operational treatment programs that targeted the exotic submersed plants Myriophyllum spicatum L. (Michigan) and Hydrilla verticillata (L.f) Royle (Florida). ELISA and HPLC results compared well (r2 = 0.84 to 0.98) across a broad range of initial fluridone treatment rates (5 to 150 μg L-1). The potential use of ELISA to monitor fluridone residues in the water in near real-time, and to use this residue data for lake specific herbicide treatment recommendations represents a unique use of ELISA technology.
Cyanobacterial Harmful Algal Blooms (CyanoHABs): Developing a Public Health ResponseLorraine C. BackerLake and Reservoir Management1040-23810743-8141181200220 - 31Cyanobacterial Harmful Algal Blooms (CyanoHABs): Developing a Public Health Response Cyanobacteria, or blue-green algae, are ancient photosynthetic organisms that grow in brackish or fresh water. Species within several genera and some strains within these species produce potent toxins that can induce severe illness in animals and people. Although cyanobacterial toxins (cyanotoxins) are important environmental contaminants, public health activities are limited to emergency responses to specific poisoning events. However, more long-term public health issues, such as cyanotoxins in drinking water, have also been identified. The potential for human exposure to cyanobacterial toxins through their drinking water has been inadequately evaluated, and the public health impact from exposure to these toxins remains unknown. The response to this emerging issue will include assessing exposure, conducting epidemiologic research, and providing public health interventions.
Effects of Point-Source Removal on Lake Water Quality: A Case History of Lake Tohopekaliga, FloridaVincent P. WilliamsLake and Reservoir Management1040-23810743-81411742001315 - 329Effects of Point-Source Removal on Lake Water Quality: A Case History of Lake Tohopekaliga, Florida Lake Tohopekaliga (9,840 ha) is part of the Kissimmee River system headwaters in central Florida. Point source discharges to the lake and its tributaries began in the 1950s. By the early 1960s four municipal wastewater treatment plants were discharging secondary effluent that contained high concentrations of phosphorus and nitrogen. Rapid population growth and treatment plant expansion began in the 1960s, and by 1969 the lake had experienced deterioration of water quality, aquatic habitat, and biological communities. By 1979, annual phosphorus loading to the lake was eleven times higher than under natural conditions and nitrogen loads had nearly doubled. Efforts to reduce phosphorus concentrations in effluent from the two largest point sources began in 1982, followed by complete removal of all wastewater treatment plant discharges by 1988. Ten years later, Lake Tohopekaliga had experienced reductions in total phosphorus (80 percent), ortho-phosphorus (95 percent), total nitrogen (50 percent), and chlorophyll a (30 percent). Secchi disk transparencies increased an average of 50 percent. Measurable improvements in water quality were also documented for downstream lakes Cypress, Hatchineha, and Kissimmee. No water quality changes were noted in neighboring East Lake Tohopekaliga, which served as a comparison lake for this study.
Seasonal Patterns of Chlorophyll a and Secchi Disk Transparency in Lakes of East-Central Minnesota: Implications for Design of Ground- and Satellite-Based Monitoring ProgramsTeresa H. Stadelmann; Patrick L. Brezonik; Steven KloiberLake and Reservoir Management1040-23810743-81411742001299 - 314Seasonal Patterns of Chlorophyll a and Secchi Disk Transparency in Lakes of East-Central Minnesota: Implications for Design of Ground- and Satellite-Based Monitoring Programs A data base consisting of growing-season measurements of chlorophyll a (chla) and Secchi disk transparency (SD) on lakes in the seven-county metropolitan area of the Twin Cities (Minneapolis and St. Paul, MN) was analyzed statistically to determine the consistency of seasonal patterns among lakes in the region. The data base included 370 lake-years of measurements on 145 lakes obtained between 1986 and 1997. Distinct patterns were found for both trophic variables, with maximum chla and minimum SD occurring from late July through mid-September in most lakes. Lake geometry, air temperature, and precipitation had little effect on seasonal patterns. Strong relationships (r2 values of 0.91 and 0.84) were found between average chla and maximum chla and between average SD and minimum SD for the growing season. The relationships were not affected by trophic state, lake geometry, precipitation, or temperature classes. Numbers of observations needed to estimate the growing season mean with specified relative errors were calculated for both chla and SD. Given the limitations on the frequency of data collection by both conventional means and satellite imagery, an index period of late July to mid September was found to be the optimal time to measure trophic conditions in TCMA lakes. During this period, lakes behave similarly, and in-lake variability is at a minimum for SD. Regression relationships to estimate growing season mean from 1-3 observations during this period have r2 values of 0.73-0.90 for chla and 0.83-0.90 for SD. Application of index-period lake monitoring by satellite imagery or conventional means has the potential to significantly increase the number of lakes assessed each year with minimal additional cost and effort.
Particulate Organic Carbon Patterns in a Mainstem Reservoir, Kentucky Lake, USAP. M. Yurista; K. Johnston; G. Rice; G. W. Kipphut; D. S. WhiteLake and Reservoir Management1040-23810743-81411742001330 - 340Particulate Organic Carbon Patterns in a Mainstem Reservoir, Kentucky Lake, USA Particulate carbon was measured spatially and temporally in the mainstem and embayments of Kentucky Lake U.S.A., the largest reservoir on the Tennessee River system. Samples were collected on pre-combusted glass fiber filters and particulate carbon and nitrogen determined with a CHN analyzer. An annual cycle was observed in the reservoir mainstem where peak particulate concentrations occurred primarily during the summer (with a yearly average 629 μg C·L-1). Concentrations of particulate carbon in embayments correlated with differential land-use practices on either side of the reservoir. Primarily agricultural western side embayments had elevated particulate carbon concentrations (1062 μg C·L-1). Forested eastern side embayments had average particulate carbon concentrations (736 μg C·L-1) that were more comparable to the mainstem. Contributions to summer POC in the reservoir mainstem were mainly from autochthonous sources, while contributions from upstream allochthonous sources were dominant during the winter.
Establishing Relationships Among Nutrient Concentrations, Phytoplankton Abundance, and Biochemical Oxygen Demand in Minnesota, USA, RiversSteven Heiskary; Howard MarkusLake and Reservoir Management1040-23810743-81411742001251 - 262Establishing Relationships Among Nutrient Concentrations, Phytoplankton Abundance, and Biochemical Oxygen Demand in Minnesota, USA, Rivers In this study, we demonstrated significant and predictable relationships among nutrients, algae, and biochemical oxygen demand (BOD) in five medium to large Minnesota, USA, rivers. These rivers were distributed across three ecoregions ranging from the Northern Lakes & Forests (NLF) (low nutrients), to the North Central Hardwood forests (NCHF) (intermediate nutrients), to the Western Corn Belt Plains (WCBP) (high nutrients). River order varied, allowing comparisons of periphyton-dominated rivers to phytoplankton-dominated rivers. Summer flows in 1999 were significantly higher than 2000 and, as a result, the “age” of the water (residence time) was greater in 2000. The lower and more stable flows generally resulted in higher algal concentrations in 2000 as evidenced by paired comparisons between sites and years. Seston composition varied not only in terms of origin of the seston: benthic vs. planktonic, but also along a gradient of nutrient enrichment. Benthic diatoms were a significant proportion in clear, low nutrient rivers in the NLF but declined in significance in more nutrient rich NCHF rivers where planktonic green and blue-green algae became more prominent. In the more turbid and high nutrient WCBP rivers, highly tolerant blue-greens were common. Regardless of origin of the seston, rivers with high nutrients exhibited high chlorophyll and high BOD while those with low nutrients exhibited the inverse. The linkages established here will contribute to nutrient criteria development and nutrient or dissolved oxygen (DO)-based Total Maximum Daily Loading (TMDL) studies.
Under Ice Water Movements Induced by Mechanical surface Aeration and Air InjectionTheron G. Miller; W. C. Mackay; David T. WaltyLake and Reservoir Management1040-23810743-81411742001263 - 287Under Ice Water Movements Induced by Mechanical surface Aeration and Air Injection We tested the hypothesis that successful lake aeration for winterkill prevention induces large-scale (whole-lake) convective flow rather than discrete aerated cells. Discrete circulating cells were not identified using mechanical surface aeration or air injection. Thermal destratification reached the most distant shorelines (up to 900 m). However, dissolved oxygen levels began to decline at about 600 m in lakes with surface aerators and at about 800 m with air injection. Vertical mixing was determined by the depth below the diffusers or surface aerators (as opposed to zmax). In addition, small depressions or distinct basins separated from the aerated basin by a shallow sill stratified and tended toward anoxia as winter progressed. Near-field velocity and dye measurements helped define zones of detrainment and entrainment near the aeration devices. These observations revealed a new conceptual model comprised of single detrainment and entrainment plumes separated by a sheer zone.
Dissolved Oxygen Depletion in a Small Deep Lake with a Large Littoral ZoneOmid Mohseni; Heinz G. Stefan; David Wright; Gerald J. JohnsonLake and Reservoir Management1040-23810743-81411742001288 - 298Dissolved Oxygen Depletion in a Small Deep Lake with a Large Littoral Zone Advection and its influence on water quality (density currents and the fate of transported materials, metalimnetic oxygen depletion, etc.) are well established for reservoirs and other lakes with well-defined inflows. This paper provides an example of the potential importance of these processes in small lakes with limited inflow. Viewing such lakes as one-dimensional systems may severely limit our understanding of their dynamics. Holland Lake, a small and deep mesotrophic lake (0.14 km2 surface area and 18.8 m maximum depth) has been considered for stocking with brown trout because it provides extensive cold-water during the summer. Unfortunately, an anoxic layer of about 1.5 to 3 m thickness develops in the upper metalimnion resulting in a negative heterograde dissolved oxygen profile, and eliminating any trout habitat during July and August. The findings of a field study suggest that the occurrence of the metalimnetic oxygen minimum is related to the presence of substantial macrophyte beds in the shallow bays, the particular morphometry of the lake (69% littoral zone), and a significant groundwater inflow and outflow. Density current intrusions that transport oxygen depleted water of high detritus content from the bottom of the shallow bays into the metalimnion of the deep basin in early summer are consistent with exceptionally high observed oxygen depletion rates. It is this horizontal convective transport of materials within the lake in addition to phytoplankton settling from the photic zone above, that strongly affects the dissolved oxygen deficiency in the upper metalimnion of the deep main basin. To create a brown trout habitat, metalimnetic aeration will be required.
Paleolimnological Study of Willard and Russell Ponds in New HampshireSushil S. Dixit; Jody N. Connor; Stephen C. LandryLake and Reservoir Management1040-23810743-81411732001197 - 216Paleolimnological Study of Willard and Russell Ponds in New Hampshire Long-term environmental trends in Willard and Russell ponds in New Hampshire were assessed using paleolimnological techniques. Algal microfossils (diatom valves and chrysophyte scales) and pollen remains were analyzed from sediment cores representing the depositional environment of the last 200-300 years. Sediment characteristics and geochemical data were also studied to assess past limnological and watershed changes. The export of ions from the watershed has increased in both ponds and trace metal concentrations in sediments have increased over the post-industrial period. Pollen data suggest that the terrestrial vegetation in the watershed had changed in the past. Stratigraphic changes in diatom and chrysophyte taxa indicated lakewater quality changes in Willard and Russell ponds in the past. Diatom assemblages were quantified to infer past total phosphorus (TP), pH, and chloride (CI) concentrations, using diatom-based inference models that have been developed for the lakes in the northeastern USA. Past inferred TP concentrations remained relatively unchanged and both water bodies can be categorized as oligotrophic for the past 200-300 years. However, inferred pH and CI levels have changed in the study ponds. Although changes in inferred CI are most likely related to watershed disturbances, the recent decline in inferred pH is most likely due to increased acidic precipitation. The study shows the usefulness of a paleolimnological approach in determining long-term water quality monitoring trends. These long-term data would be useful in developing effective lake management and restoration plans in New Hampshire.
Long-Term Changes in the Sediment Chemistry of a Large Shallow Subtropical LakeM. M. Fisher; K. R. Reddy; R. Thomas JamesLake and Reservoir Management1040-23810743-81411732001217 - 232Long-Term Changes in the Sediment Chemistry of a Large Shallow Subtropical Lake Nitrogen (N) and phosphorus (P) content and selected physico-chemical properties of Lake Okeechobee sediments were measured in 1988 and 1998. Based on these measurements, sediments were classified as mud, littoral, peat, sand or rock. Although some minor redistribution has occurred over the previous decade, mud sediments of Lake Okeechobee essentially occupy the same total area. Total surface sediment N and P showed little overall change in the ten-year period. However, lake-wide spatial patterns indicate some localized decreases of total P content in the littoral and northern regions of the lake. Porewater dissolved reactive P showed significant increases at most sites, suggesting that the surface sediments are losing their ability to absorb soluble P. Nutrient management practices in the drainage basin did not lead to decreased levels of N and P in the sediments of the lake.
Water Quality Indicators for Reservoirs: A Conceptual FrameworkRobert H. Kennedy; Kent W. ThorntonLake and Reservoir Management1040-23810743-81411732001188 - 196Water Quality Indicators for Reservoirs: A Conceptual Framework Protection and successful stewardship of water resources will require the development and application of management approaches linking societal expectations, designated resource uses and observed resource conditions to management performance. Described here is a conceptual framework that includes indicators of condition and trends, diagnostic and management indicators, and measures of management performance as they relate the management of water resource development projects. When properly applied, these indicators provide valuable insight to complex environmental problems and can be used to effectively support the management and decision-making process.
Managing Drinking Water SuppliesG. Dennis Cooke; Robert H. KennedyLake and Reservoir Management1040-23810743-81411732001157 - 174Managing Drinking Water Supplies Efforts to provide safe drinking water cannot begin at the treatment plant. Processes occurring in the watershed can adversely influence drinking water reservoirs, and understanding linkages between these processes and reservoir water quality provides the basis for protecting or improving source water quality. Since the presence of molecules responsible for taste, odor and algal toxin problems, and for the formation of disinfection by-products (DBP) is often related to reservoir trophic conditions, sound and cost-effective water treatment approaches must include considerations for reservoir management. Source water management efforts should include both watershed management, as a means to reduce the loading of materials to the reservoirs, and in-reservoir treatments that ameliorate or minimize the symptoms of eutrophication. Discussed here are considerations for maintaining safe drinking water, water quality assessment approaches, and common methods for managing reservoir water quality.
Considerations for Establishing Nutrient Criteria for ReservoirsRobert H. KennedyLake and Reservoir Management1040-23810743-81411732001175 - 187Considerations for Establishing Nutrient Criteria for Reservoirs The recent requirement to establish nutrient criteria for lakes and reservoirs provides the means for water resource management agencies to link watershed influences and water quality responses. Establishing reference conditions, as required for setting realistic criteria, raises a number of questions concerning the potential importance of differences and similarities between lakes and reservoirs. Discussed here are considerations for establishing reservoir nutrient criteria, including linkages between reservoir design, operation and water quality, spatial heterogeneity in water quality conditions, and analytical approaches.
Determinants of Farmer Behavior: Adoption of and Compliance with Best Management Practices for Nonpoint Source Pollution in the Skaneateles Lake WatershedEric W. Welch; Frederick J. Marc-Aurele Jr.Lake and Reservoir Management1040-23810743-81411732001233 - 245Determinants of Farmer Behavior: Adoption of and Compliance with Best Management Practices for Nonpoint Source Pollution in the Skaneateles Lake Watershed Policy makers and public managers have recently implemented a wide range of watershed management programs designed to reduce nonpoint pollution from agriculture. This paper focuses on the progress of one such program. Skaneateles Lake, New York is the drinking water supply of Syracuse City. Granted “filtration avoidance” under the Surface Water Treatment Rules - allowance of unfiltered water supply conditional upon heightened source protection activities - the City, in cooperation with other agencies, established the Skaneateles Lake Watershed Agricultural Program (SLWAP) in 1994 as one element of a broader watershed protection plan. The SLWAP is a 5-10 member interagency pollution prevention program designed to work cooperatively and independently with watershed farmers to develop Whole Farm Plans that incorporate pollution minimizing best management practices. The program is voluntary and not all farmers have agreed to opt in. Using a modified behavioral model, this paper examines adoption and compliance behavior of farmers in the Skaneateles Lake Watershed in New York State. Findings indicate two stages of adoption. Early adopters have lower incomes, indicate that farming is their primary source of income, perceive fairer and more equitable treatment by regulators, believe the Best Management Practices (BMP) will have the desired effect, and are more fearful of regulatory consequences if the Whole Farm Planning effort fails. We call this first stage “regulatory push.” Late adopters are more environmentalist and more influenced by other farmers and the community. We call this second stage “community pull.” In addition, findings regarding compliance indicate that farmers and the management team diverge in their assessments of progress toward implementation of Best Management Practices, indicating some potentially significant communication problems. Concluded recommendations for management of voluntary programs for farmers include: (1) initial implementation efforts should seek out those community leaders are more likely to be cooperative, (2) regulatory threat may be useful during the initial implementation period, and (3) evaluation criteria must be developed cooperatively with and clearly communicated to farmers.
Citizen Monitoring of Aquatic Bird Populations Using a Florida LakeMark V. Hoyer; John Winn; Daniel E. Canfield Jr.Lake and Reservoir Management1040-23810743-8141172200182 - 89Citizen Monitoring of Aquatic Bird Populations Using a Florida Lake Five years of monthly bird counts on a 2.32 km2 lake in north central Florida were used to examine the ability of a citizen volunteer to monitor aquatic bird populations. When compared to published aquatic bird data, collected by professional biologists, the citizen volunteer was able to accurately assess bird abundance and species richness. The monthly counts over a five-year period were also used to examine seasonal patterns in aquatic bird use. We highly recommend the development of citizen based aquatic bird monitoring programs for the assessment of reportedly declining aquatic bird populations. This would be especially useful if entire states programs could be developed to monitor regional as well as temporal trends in aquatic bird populations.
Design Parameters for Artificial Aeration of Ice-Covered LakesS. A. McCord; S. G. SchladowLake and Reservoir Management1040-23810743-81411722001121 - 126Design Parameters for Artificial Aeration of Ice-Covered Lakes Numerous lakes in cold climates require artificial aeration to maintain fish habitats during ice-cover periods. Mechanical surface aerators (“splashers”) are one type of aeration system popular in midwestern parts of the U.S. and Canada. A method is presented to represent the most important physical characteristics of splasher systems designed for small lakes through two dimensionless parameters. Data from several lakes in Wisconsin and Alberta, Canada, where splashers have been operated were used to determine a preliminary, constrained range of values for these two design parameters.
Effects of Shoreline Urbanization on Littoral Fish AssemblagesPerry F. Trial; Frances P. Gelwick; Mark A. WebbLake and Reservoir Management1040-23810743-81411722001127 - 138Effects of Shoreline Urbanization on Littoral Fish Assemblages We evaluated modifications associated with shoreline urbanization with regard to effects on littoral habitat use by fishes in Lake Conroe, TX. Among four habitat types present, two had nonurbanized shorelines and were either vegetated or nonvegetated, and two had urbanized nonvegetated shorelines modified with either riprap or retaining walls. In each habitat type, four sites were randomly chosen for repeated sampling (once in each of fall, winter, spring, and summer) using depletion electrofishing inside a block-netted area. Nonvegetated and walled habitats had fewest species and weakest seasonal dynamics. Beginning in fall, vegetated habitat was characterized by various small-bodied taxa, primarily water-column and surface-feeding invertivores and piscivores, but as vegetation died back through the winter, it contained fewer characteristic species. Then in spring and summer, number of characteristic species in vegetation increased to include small-bodied benthic species, and large-bodied piscivores. The species association in walled habitat changed least across seasons, and was characterized by yellow bass (Morone mississippiensis). Associations in nonvegetated and walled habitats had fewer characteristic species than did other habitats, but these increased overall diversity of littoral assemblages in the reservoir. Cumulative effects of increasing urbanization accompanied by conversion of vegetated shoreline to walled habitat would lead to impoverished littoral assemblages. Riprap might be an acceptable alternative to retention walls for stabilizingshorelines. However, addition or protection of native aquatic vegetation also should be considered, especially with regard to mitigation of effects on fishes that are seasonally or uniquely associated with that habitat type, and whose populations had declined following past efforts to control vegetation.
Hepatic Copper Concentrations and Condition Factors of Largemouth Bass (Micropterus salmoides) and Common Carp (Cyprinus carpio) from Copper Sulfate-Treated and Untreated ReservoirsMichael A. Anderson; Michael S. Giusti; William D. TaylorLake and Reservoir Management1040-23810743-8141172200197 - 104Hepatic Copper Concentrations and Condition Factors of Largemouth Bass (Micropterus salmoides) and Common Carp (Cyprinus carpio) from Copper Sulfate-Treated and Untreated Reservoirs The application of copper sulfate to surface waters for nuisance algae control has been practiced for decades. Despite its long history of use, questions persist about the fate and bioavailability of copper (Cu) in water bodies receiving copper sulfate applications. This study compares the hepatic Cu content of largemouth bass (Micropterus salmoides) and common carp (Cyprinus carpio) sampled from two reservoirs in southern California with contrasting copper sulfate treatment histories. Lake Mathews is the terminal reservoir for the Colorado River Aqueduct and has received over 2000 tons of CuSO4·5H2O over the past ~20 years. As a result of repeated copper sulfate treatment, Lake Mathews has an average Cu sediment content of 290 μg·g-1 dry weight. Copper Basin Reservoir, also part of the Colorado River Aqueduct system, has not previously received any CuSO4 applications and thus has a much lower sediment Cu content (8 μg·g-1). The mean hepatic Cu content of small bass (mean length ~24 cm) was significantly higher for individuals sampled from Lake Mathews than from Copper Basin Reservoir (22.9±20.5 vs. 4.3±4.4 μg·g-1, respectively), although no statistically significant difference (at p≤0.05) was found for large bass (mean length ~41 cm) from the two reservoirs. The mean hepatic Cu concentration of carp from Lake Mathews was significantly higher (at p≤0.05) than that of carp from Copper Basin Reservoir (76.8±42.3 vs. 51.3±22.4 μg·g-1, respectively). No apparent negative effects associated with copper sulfate application or copper accumulation within fish were found, however, as condition factors (K) for fish from Lake Mathews were either comparable to or higher than those from Copper Basin Reservoir (e.g., for small bass, K was 1.78±0.11 vs. 1.46±0.10, respectively).
A Protocol for Standardizing Secchi Disk Measurements, Including Use of a Viewer BoxDavid G. SmithLake and Reservoir Management1040-23810743-8141172200190 - 96A Protocol for Standardizing Secchi Disk Measurements, Including Use of a Viewer Box Despite being used by limnologists and oceanographers for over a century, the use of the Secchi disk for estimating water transparency has no standardized protocol. Because of this lack of uniformity, and the inherent optical problems with most current Secchi depth procedures, an appeal is made for production of a standardized protocol for Secchi observations. A possible protocol, including the use of a closed-ended viewer box on the sunny side of the boat, is suggested here. To assist in protocol development, this paper briefly reviews some aspects of optical physics and examines some recent field measurements made by staff of New York City Department of Environmental Protection. These measurements were made using a closed-ended viewer box and are compared with simultaneous naked-eye measurements. The use of a viewer box increases Secchi depth measurement by removing the interfering effects of water surface glare and glitter. A viewer box also increases between-observer precision. Measurements made both with and without the viewer box are slightly greater on the shady side of the boat than on the sunny side; the latter is the preferred side if Secchi data are to be related to other optical properties. The difference between viewer box and naked eye measurements increases with increasing wave height but not with increasing illuminance.
Natural and Management-Induced Reduction in Monimolimnetic Volume and Stability in a Coastal, Meromictic LakeStuart D. Ludlam; Brian DuvalLake and Reservoir Management1040-23810743-8141172200171 - 81Natural and Management-Induced Reduction in Monimolimnetic Volume and Stability in a Coastal, Meromictic Lake Lower Mystic Lake is a coastal meromictic lake with a northern and southern basin. Although the southern basin has remained meromictic, the northern, shallower basin became holomictic in the early 1980s. A secondary chemocline forms above the primary chemocline, so that mixing during autumnal overturn does not always reach to the depth of the primary chemocline. The secondary chemocline may develop and intensify during periods when wind action and seiche activity are not expected, and may persist as a distinct feature for over a year. The source of the solutes in the secondary chemocline appears to be the primary chemocline and the monimolimnion. The Amelia Earhart Dam, constructed in 1966, prevents any further influx of seawater that was necessary to maintain the meromictic stratification. As a result, depth of the primary chemocline has increased at an irregular rate since the last influx of seawater. Between 1966-1994 the chemocline was eroded downwards 12 m, causing a 95% reduction in monimolimnetic volume. Of the total loss of volume between 1968 and 1994, approximately 4% was caused by management pumping water from the monimolimnion, that is, about 29% of the volume of the chemocline and monimolimnion as they existed in 1977, just prior to the major effort in treatment. The remainder of the monimolimnion was removed by wind action, convective circulation and other natural means. Meromictic stability showed a linear decrease between 1974 and 1994. During that time period, average annual loss of meromictic stability due to natural processes amounted to approximately 64 g-cm cm-2 yr-1 for the south basin alone, and 84 gm-cm cm-2 yr-1 for the lake as a whole. Using stability measurements it was projected that the monimolimnion would most probably mix completely into the lake by approximately 2013-2014. Overall, completion of the Amelia Earhart Dam had a greater effect on the loss of the monimolimnion than efforts to remove this stratum by pumping as it prevented replacement of water eroded from the chemocline with fresh seawater.
Correlations of Sedimentary Diatoms with Watershed Land Use and Limnological Conditions in Northern New Jersey LakesB. H. Hill; J. P. KurtenbachLake and Reservoir Management1040-23810743-81411722001105 - 120Correlations of Sedimentary Diatoms with Watershed Land Use and Limnological Conditions in Northern New Jersey Lakes Sedimentary diatoms were collected from 62 New Jersey lakes and correlated with limnological and land use variables. Four diatom attributes (species richness, percentage dominance by a single diatom species, percentage acidobiontic species, percentage eutraphentic species) and 4 diatom indices, Centrales:Pennales (C/P), Araphidinaea:Centrales (A/C), Generic Diatom (GI), and diatom index of biotic integrity (DIBI), were compared to the environmental variables. Lakes were classified as forested lakes (±80% the watershed in forests), mixed land use lakes (21-79% forests), or deforested lakes (≤20% forests) based on the satellite imagery. Forested lakes had significantly lower specific conductance and pH, greater ZSD and hypo limnetic DO, and less urban land use within their watersheds than either mixed land use or deforested lakes. Forested lakes also had greater species richness, lesser dominance by single species, more acidobiontic diatoms, fewer eutraphentic diatoms, lower C/P, and higher DIBI scores. There were no significant differences among lake classes for A/C or GI indices. The 4 diatom attributes and 4 diatom indices were correlated with each other, though A/C was not significantly correlated with any of the diatom attributes or indices. The remaining 3 diatom indices were highly correlated with taxa richness, percentage dominance, and percentage acidobiontic species. The attributes and indices were variously correlated with the 13 limnological and watershed land use variables, with alkalinity, specific conductance, pH, ZSD, and percentage of the watershed in forests and urban land uses exhibiting the strongest correlations. Canonical correlation analysis revealed significant correlations between the diatom attributes and indices and the environmental axis related to lower alkalinity and pH, and higher ZSD and percentage of the watershed in forests. Our results suggest that diatom attributes and indices are useful indicators of the ecological condition of lakes and that these attributes and indices respond to human disturbances within a lake's watershed. Of the indices tested, the DIBI appears to be the most useful, significantly correlating with stressors and limnological variables of interest, especially the loss of forests from watersheds. The results support the use of sedimentary diatom attributes and indices for monitoringlake water-quality and watershed land use changes relative the management of these resources.
Comparison of Submerged Aerator EffectivenessConnie D. DeMoyer; John S. Gulliver; Steven C. WilhelmsLake and Reservoir Management1040-23810743-81411722001139 - 152Comparison of Submerged Aerator Effectiveness The effectiveness of three different submerged aerators (diffusers), a membrane diffuser, a coarse bubble diffuser, and a soaker hose, is compared by analyzing their performance parameters at varying gas flow rates and water depths of up to 10 meters. The type of diffuser chosen for a specific application depends on aeration characteristics such as the total mass transfer coefficient, standard oxygen transfer rate (SOTR), standard oxygen transfer efficiency (SOTE), and standard aeration efficiency (SAE). From experimental data, the effects of the gas flow rate and submerged depth on the total mass transfer coefficient and SOTR are determined up to a 10 meter depth. As the flow rate and diffuser depth are increased, the mass transfer coefficient and the SOTR increase for all three diffusers. At low gas flow rates, the segment of soaker hose transfers oxygen at the highest rate. The coarse bubble diffuser transfers oxygen at a lesser rate than the soaker hose but is capable of performing at higher gas flow rates. The membrane diffuser performance resembles the high transfer of a soaker hose before approaching the transfer behavior of the coarse bubble diffuser at higher flow rates. Relationships are also defined for the SOTE and SAE. Non-dimensional parameter correlations quantify the dependence of the performance parameters on the gas flow rate and depth and provide a means of predicting diffuser behavior for specified system applications.
Impacts of Water Column Turbidity on the Survival and Growth of Vallisneria americana Winterbuds and SeedlingsRobert D. Doyle; R. Michael SmartLake and Reservoir Management1040-23810743-8141171200117 - 28Impacts of Water Column Turbidity on the Survival and Growth of Vallisneria americana Winterbuds and Seedlings Survival and growth of Vallisneria americana winterbuds was significantly related to both initial winterbud size and to the water column turbidity under which the plants were grown. Larger winter buds showed better survival and better growth than did smaller ones. Turbidity likewise significantly impacted the survival and growth of the plants. Over the turbidity range of 0.2-45 NTU (53-7% total incident light), the plants were shown to have progressively poorer survival and to produce fewer rosettes and total number of leaves. Vallisneria americana seedlings were likewise influenced by turbidity. Under high turbidity conditions the seedlings had significantly higher mortality, while surviving plants produced fewer rosettes and accumulated less biomass than seedlings grown under low turbidity conditions. In addition, under turbid conditions the seedlings had to invest proportionally more energy into above-ground tissues.
Impacts of Water Column Turbidity on the Survival and Growth of Vallisneria americana Winterbuds and SeedlingsRobert D. Doyle; R. Michael SmartLake and Reservoir Management1040-23810743-8141171200117 - 28Impacts of Water Column Turbidity on the Survival and Growth of Vallisneria americana Winterbuds and Seedlings Survival and growth of Vallisneria americana winterbuds was significantly related to both initial winterbud size and to the water column turbidity under which the plants were grown. Larger winterbuds showed better survival and better growth than did smaller ones. Turbidity likewise significantly impacted the survival and growth of the plants. Over the turbidity range of 0.2-45 NTU (53-7% total incident light), the plants were shown to have progressively poorer survival and to produce fewer rosettes and total number of leaves. Vallisneria americana seedlings were likewise influenced by turbidity. Under high turbidity conditions the seedlings had significantly higher mortality, while surviving plants produced fewer rosettes and accumulated less biomass than seedlings grown under low turbidity conditions. In addition, under turbid conditions the seedlings had to invest proportionally more energy into above-ground tissues.
Book ReviewJohn J. NeyLake and Reservoir Management1040-23810743-8141171200166Book Review
Influence of Factors Associated with Water Level Drawdown on Phosphorus Release from SedimentsR. Lawrence Klotz; Susan A. LinnLake and Reservoir Management1040-23810743-8141171200148 - 54Influence of Factors Associated with Water Level Drawdown on Phosphorus Release from Sediments Studies on lake sediments showed that drying and freezing, as would occur during the management practice of water level drawdown, increased the release of phosphorus from the sediments over controls. P release from sediments increased as a result of drying in all ten lake sites studied, but the amount of P released varied significantly between sites. Phosphorus release ranged from 0.9 to 38.2 μg·g-1 dry weight sediment and the increase over wet controls ranged from 3 to 84 fold. The effect occurred within 4 days of drying in the laboratory. Drying of the epilithon on cobbles resulted in higher P release. Freezing of sediments also resulted in increased nutrient release, with 70 times more P released from frozen sediments compared to unfrozen controls. The full effect of freezing was realized within 3 days. The combined effect of drying then freezing did not increase the amount of P released above that of sediments that were frozen without prior drying. P release as a result of drying was significantly correlated with sediment P and organic content. The data indicate that the P released resulted from the death of microorganisms due to drying and freezing. The results show that lake drawdown may significantly increase internal P loading to lakes of central New York State.
On Determining the Principal Source of Phosphorus Causing Summer Algal Blooms in Western Washington LakesEugene B. Welch; Jean M. JacobyLake and Reservoir Management1040-23810743-8141171200155 - 65On Determining the Principal Source of Phosphorus Causing Summer Algal Blooms in Western Washington Lakes Internal loading of total phosphorus (TP) calculated from mass balance averaged 68±21% of the total (internal + external) summer loading in 14 of 17 western Washington lakes that had internal loading. Moreover, whole-lake mean TP for the 16 lakes with complete mass balance data was 50 ±9 μg·L-1, which was similar to TP (51±18 μg·L-1) predicted from summer internal P loading determined by the maximum change in lake TP. Lake TP predicted from summer external loading, assuming a nominal retention coefficient, was only 30±9 μg·L-1. In-lake management measures to control internal loading had been either implemented or recommended in 14 of the 17 lakes. Summer P was substantially reduced in 10 of 12 lakes (or separate lake basins) receiving in-lake treatments, substantiating the dominant effect of internal loading. These observations indicate that emphasis on reducing external loads only, through watershed best-management practices (BMPs), without in-lake measures, would not have been the most cost-effective approach to control summer algal blooms in these lakes, especially if external loads were nonpoint and of minor importance during summer when algal problems are most prevalent. Comparison of external and internal P loads during summer, as illustrated here, is recommended so that in-lake controls are considered with watershed controls in a balanced approach to cost-effective lake management.
Integrating Nature Conservation with Hydro-Electric Development: Conflict Resolution with Lakes Manapouri and Te Anau, Fiordland National Park, New ZealandAlan F. Mark; Keith S. Turner; Carol J. WestLake and Reservoir Management1040-23810743-814117120011-25Integrating Nature Conservation with Hydro-Electric Development: Conflict Resolution with Lakes Manapouri and Te Anau, Fiordland National Park, New Zealand Thirteen years of public debate and protest followed the New Zealand Government's 1960 formal agreement with a multinational consortium to raise Lakes Manapouri (142 km2) and Te Anau (352 km2), in Fiordland National Park, to maximise hydro-electric generation for an aluminum smelter proposed by Comalco Ltd. This controversy was a major factor in the 1972 change of government which rejected lake raising and also appointed Guardians, from among the campaign leaders, to advise on lake management. Lake management guidelines were devised from geomorphological and ecological studies correlated with a 37-year lake level record. High, Main and Low Operating Ranges were recognised within the natural variation (Te Anau 3.5 m; Manapouri 4.8 m). High Operating Range defines both maximum duration at a particular level and minimum periods of subsequent lowering to satisfy ecological requirements of shoreline forest. Low Operating Range defines both draw-down rates (to prevent slumping of fine beach sediments) and maximum annual duration at particular levels (to prevent combing down and possible loss over narrow shelves, of beach sediments). Main Operating Ranges have negligible restrictions. The guidelines were verified in practice and incorporated in legislation in 1981. Monitoring of shoreline vegetation and beaches has confirmed achievement of objectives. Wide consultation, aimed at further conflict resolution and replacement of empowering legislation by consents under the 1991 Resource Management Act, was completed, with guidelines and monitoring incorporated, in 1996. We believe the scientifically based management guidelines have effectively integrated nature conservation with hydro-electric development in Fiordland National park, a World Heritage Area since 1986. This approach should be applicable to natural lakes elsewhere.
Effects of Fisheries Management and Lakeshore Development on Water Quality in Diamond Lake, OregonJ. M. Eilers; C. P. Gubala; P. R. Sweets; D. HansonLake and Reservoir Management1040-23810743-8141171200129 - 47Effects of Fisheries Management and Lakeshore Development on Water Quality in Diamond Lake, Oregon Paleolimnological techniques were used to assess water quality changes in a heavily used recreation lake in the Oregon Cascades. Diamond Lake was fishless prior to 1910, but has been intentionally stocked with rainbow trout annually and unintentionally stocked with tui chub in the 1930s and the 1990s. The lake was converted from a mesotrophic system to an eutrophic lake as a consequence of watershed inputs of nutrients associated with shoreline development and biomanipulation in the form of fisheries management. Despite installation of a sewage collection and diversion system, Diamond Lake has increased in sediment accumulation rate and the diatom community has shown an increase in Fragilaria crotonensis and Asterionella formosa, species which are often associated with eutrophication. The two largest increases in sediment accumulation rate and alterations in the diatom community correspond most closely with the two increases in the tui chub population rather than shoreline development. Diatom-inferred (DI) pH increased from 7.95 circa 1910 to over 8.20 in the 1940s. The effects of a rotenone treatment in 1954 to eliminate the tui chub are evident in the short-term decrease in DI- pH and the response of the diatom community. The lake also experienced a major increase in zooplankton abundance in the 20th century as indicated by the remains in the sediment. The results illustrate the need to consider both external and internal sources of nutrients in lake restoration and management attempts.
Recent Eutrophication Histories in Lac Ste. Anne and Lake Isle, Alberta, Canada, Inferred Using Paleolimnological MethodsJules M. Blais; Katharine E. Duff; David W. Schindler; John P. Smol; Peter R. Leavitt; Michael AgbetiLake and Reservoir Management1040-23810743-81411642000292 - 304Recent Eutrophication Histories in Lac Ste. Anne and Lake Isle, Alberta, Canada, Inferred Using Paleolimnological Methods A paleolimnological analysis of Lac Ste. Anne and Lake Isle, two eutrophic lakes in central Alberta, Canada, confirmed that they were naturally eutrophic, but have become increasingly eutrophic after the 1960s as 27% and 24% of their watersheds, respectively, were developed for urban and agricultural purposes. This was shown by a predominance of Chironomidae head capsules indicating periodic anoxia in bottom waters, high abundances of eutrophic diatoms (e.g., Aulacoseira granulata, Fragilaria crotonensis, Stephanodiscus niagarae and S. parvus), and, in Lac Ste. Anne, an enrichment of pigments from filamentous cyanobacteria (e.g., myxoxanthophyll) in post-1960 sediments. Evidence of periodic anoxia in the profundal zone was also provided by a scarcity of reducible phosphorus in the sediments. Lac Ste. Anne showed the largest changes during the 1960s and 1970s, when increases were observed in the abundance of hyper-eutrophic diatoms (e.g., S. parvus) as well as sedimentary phosphorus fractions and algal pigments. The changes in Lake Isle were similar, but more subtle. Results indicate that reduced anthropogenic activities would still result in eutrophic systems, but some improvements in water quality would be achieved, particularly in Lac Ste. Anne.
Water Quality Changes from Human Activities in Three Northeastern USA LakesSushil S. Dixit; Aruna S. Dixit; John P. Smol; Robert M. Hughes; Steven G. PaulsenLake and Reservoir Management1040-23810743-81411642000305 - 321Water Quality Changes from Human Activities in Three Northeastern USA Lakes Diatom and chrysophyte assemblages from sediment cores were analyzed to assess the long-term trends of lake water quality in French Pond (New Hampshire), Joes Pond (Vermont), and Kenoza Lake (Massachusetts) as part of the US EPA's EMAP-SW (Environmental Monitoring and Assessment Program-Surface Waters) program in the northeastern USA. Sediment characteristics and geochemical data were also examined to interpret past limnological and watershed changes. Geochemical data indicate that exports of ions from the watersheds have increased and the lakes have received higher trace metal inputs over the post-industrial period. Stratigraphic changes in common diatom and chrysophyte taxa indicate that, over the last century, distinct water quality changes have occurred. Using the diatom- and chrysophyte-based weighted averaging inference models developed for lakes in the northeast, past changes in assemblages were used to infer trends in lakewater total phosphorus (TP), pH, and CI. In French Pond, inferred TP, pH, and CI changes were small, whereas Joes Pond and Kenoza Lake have experienced major changes. The latter two lakes have become more eutrophic, and lakewater pH and CI have also increased from their background values. Inferred water quality changes are closely related to watershed disturbances and resulting eutrophication. Our study illustrates that the inference models developed in EMAP-SW can be successfully applied in establishing long-term water quality trends in lakes throughout the northeastern USA. These models and subsequent sediment core data will help lake managers to develop effective management plans and to establish suitable targets for the restoration of other lakes of concern.
The Potential For Wave Disturbance in Shallow Florida LakesRoger W. Bachmann; Mark V. Hoyer; Daniel E. Canfield Jr.Lake and Reservoir Management1040-23810743-81411642000281 - 291The Potential For Wave Disturbance in Shallow Florida Lakes We applied wave theory to calculate the extent and frequency that we would expect wave-driven surface water movements to disturb the sediments in 36 Florida lakes covering a broad range of surface areas and mean depths. The calculated per cent of the lakebed subject to wave disturbance at one time or another ranged from 6 to 100% and the per cent of the time 50% of the lakebed was disturbed ranged from 0 to 65%. The large Florida lakes, Apopka, Okeechobee, and Istokpoga showed high levels of calculated wave disturbance, which was consistent with the conclusions of previous investigations. Historic water level fluctuations in Lake Apopka were calculated to have major effects on wave disturbance in that lake. The dynamic ratio (the square root of lake surface area in square kilometers divided by the mean depth in meters) was significantly related to various measures of wave disturbance in our sample lakes. For lakes with ratio values above about 0.8 the entire lakebed was subject to wave disturbance at least some of the time. The dynamic ratio was also related to lake water quality. We found that increases in the dynamic ratio were significantly related to decreases in water quality as measured by total phosphorus, total nitrogen, chlorophyll, and Secchi disk depth. Calculations of wind disturbance by waves need to be modified in lakes with extensive beds of macrophytes, where water levels change and in periods where climatic fluctuations result in changes in wind regimes.
A Limnological Survey of Third Sister Lake, Michigan with Historical ComparisonsT. B. Bridgeman; C. D. Wallace; G. S. Carter; R. Carvajal; L. C. Schiesari; S. Aslam; E. Cloyd; D. Elder; A. Field; K. L. Schulz; P. M. Yurista; G. W. KlingLake and Reservoir Management1040-23810743-81411642000253 - 267A Limnological Survey of Third Sister Lake, Michigan with Historical Comparisons Third Sister Lake in southeastern Michigan has been a focus of ecological studies since 1904. In 1999, we surveyed several physical, chemical, and biological parameters of the lake and compiled data collected by University of Michigan students since 1975. Comparison of dissolved oxygen profiles from years 1927-29, 1939-42 to recent data (1992-99) indicate a decrease in maximum oxygenation of bottom waters at fall turnover (8 mg O2·L-1 maximum 1927-29, 1939-42 vs. 4 mg O2·L-1 1980, 1992-93) and more rapid depletion of oxygen in the hypolimnion following stratification. In early studies, oxygen persisted (> 3 mg L-1) at all depths from mid-November to May (1927-29, 1939-42). There has been no evidence of spring mixing in recent years and bottom waters have become anoxic by late January. The diversity and density of offshore benthic organisms has declined from at least 12 species and an average density of 167000·m-2 in 1927 to 4-5 species at 15144 · m-2 in 1999. Overall, benthic populations shifted from the deepest portions of the lake (16-18 m benthos) to shallower depths and only Chaoborus was found at bottom contours > 10 m in 1999. Mean chloride concentration [Cl·] increased nearly 13-fold from 19 mg L-1 to 241 mg L-1 between 1981 and 1988, with 260 mg L-1 recorded in 1999. Calculations of whole-lake stability incorporating increases in [Cl·] indicate that about 60% more energy would be required to mix the lake following ice-out in 1999 compared to 1981. During the winter-spring transition, net respiration dominated under ice (4.1 g C·m-2 d-1) and immediately afterice-out(0.32 g C·m-2 d-1)in 1999. The phytoplankton community was dominated by cyanobacteria (Oscillatoria) from February to April. Under ice cover, bacterial abundance increased with depth from an average of 4.17 105 cells ml-1 (1-5 m) to 18.9 105 cells ml-1 (15 m).
Non-Algal Seston, Light, Nutrients and Chlorophyll in Missouri ReservoirsMatthew F. Knowlton; John R. JonesLake and Reservoir Management1040-23810743-81411642000322 - 332Non-Algal Seston, Light, Nutrients and Chlorophyll in Missouri Reservoirs Limnological measurements were performed at five or six Missouri reservoirs in June-September 1992-1995 to examine the relation of light conditions and non-algal seston (NAS) to chlorophyll (CHL) and dissolved nutrient concentrations. NAS was estimated as the sum of non-volatile suspended solids and filterable (Whatman 934AH filter) suspended solids. Mean mixed layer irradiance (Imix) varied ≈20 fold among observations, largely due to variation in light attenuation by NAS. In 42% of the observations, Imix was less than 7 E·m-2 d-1, a range where light limitation is likely. NAS comprised 15-96% (mean= 58%) of total seston and accounted for 89% of the temporal and inter-site variation in Imix. NAS was strongly correlated to total phosphorus (TP) and soluble reactive phosphorus (SRP) concentrations (r= 0.91 and r=0.84, respectively, p<0.0001). When NAS > 5 mg·L-1 or Imix was < 5 E m-2 d-1, SRP and dissolved inorganic N (DIN) were usually at concentrations capable of saturating algal nutrient uptake (SRP >3 μg·L-1, DIN >50 μg·L-1), suggesting light limitation replaced nutrient limitation under those conditions. Light limitation resulting from NAS in turbid lakes may alter the relationship of phytoplankton to phosphorus, yielding a CHL-TP relationship that is dome-shaped rather than asymptotic. Variation in the relation of NAS to TP will affect how CHL responds to nutrients in individual waterbodies.
Chlorophyll Maxima in Mountain Ponds and Lakes, Mount Rainier National Park, Washington State, USAGary L. LarsonLake and Reservoir Management1040-23810743-81411642000333 - 339Chlorophyll Maxima in Mountain Ponds and Lakes, Mount Rainier National Park, Washington State, USA Hypolimnetic chlorophyll maxima are common in clear lakes and often occur at depths with between 1 and 0.1% of the surface incident light. Little is known, however, about the concentrations of chlorophyll in thermally unstratified mountain ponds and how these concentrations compare to epilimnetic and hypolimnetic concentrations in mountain lakes. The objectives of this study were to document the concentrations of chlorophyll in thermally unstratified ponds and stratified lakes in Mount Rainier National Park (MORA) and to compare the results with concentrations and distributions of chlorophyll in clear-deep lakes in the Oregon Cascade Range and the Sierra Nevada Range. Thirty-two ponds (<2.5 m deep) and 14 lakes(>9.9 m deep) were sampled primarily during the summers of 1992 to 1996 at MORA. Water samples from near the surface (0.1-0.5 m) of ponds and near the surface and near the bottom of lakes were collected over the deepest part of each system. One exception, Mowich Lake, was sampled at seven depths between the surface and 50 m (Z=58.6 m). Chlorophyll concentrations were low in all systems, but higher in ponds (average 1.8 μg·L-1) than in lakes. Chlorophyll concentrations were higher in hypolimnetic lake samples (average 0.7 μg·L-1) than in epilimnetic lake samples (average 0.2 μg·L-1). Elevated concentrations of chlorophyll in mountain ponds, relative to those in hypolimnetic lake samples, may have been influenced by increased nutrient availability from interactions at the mud-water interface and, in this park, defecation by elk that used many of the ponds as wallows. Mowich Lake showed a chlorophyll maximum (~1.5 μg·L-1) near the lake bottom. Based on Secchi disk clarity readings, the depth of 1.0% incident surface solar radiation was greater than the maximum depths of the ponds and lakes. Comparative data from other clear-deep lakes in the Oregon Cascade Range and Sierra Nevada Range suggested that deep-chlorophyll maxima (~1.5 μg·L-1) occurred at <1.0% and > 0.1% of the incident surface solar radiation, and that the typical maximum depths ranged between 75 and 140 m during thermal stratification.
Trophic Conditions and Water Chemistry of Lakes on Cape Cod, Massachusetts, USAToby D. Ahrens; Peter A. SiverLake and Reservoir Management1040-23810743-81411642000268 - 280Trophic Conditions and Water Chemistry of Lakes on Cape Cod, Massachusetts, USA Sixty lakes and ponds distributed throughout the Cape Cod peninsula were each sampled three times during 1996-1998 in order to determine the chemical conditions of the waterbodies. The study lakes, situated on either glacial moraine, glacial outwash plain or post-glacial sand accumulations, ranged in surface area from 3.6 ha to 301 ha and in maximum depth from 1 m to 26 m. The dominant ionic species in all lakes were Na+ and Cl-, likely due to inputs from sea spray. Conductivity and the relative charge contribution from Na+, Cl- and Mg2+ increased with distance out onto the peninsula, whereas the contribution due to Ca2+ decreased along the same distance gradient. Concentrations of Mg2+ were greater than those of Ca2+ in the study lakes, and the concentrations of the latter cation were very low compared to other areas in the northeast U.S. Except for the eutrophic lakes situated on the post-glacial sand accumulations on the outer tip of Cape Cod, the water bodies were, in general, low in total phosphorus, total nitrogen and chlorophyll-a levels, had high Secchi disk depths, and were best classified as oligotrophic. The pH and alkalinity (except for lakes situated on the post-glacial sand accumulations) declined with distance out onto the peninsula. The mean pH and alkalinity of water bodies located closest to the mainland were 6.8 and 71 μeq·L-1, respectively, but declined to only 5.3 and-7.5 μeq·L-1 on the outer Cape. Findings are compared to other studies in the northeast U.S.
Long and Short Term Effects of Waterfowl on Collins Lake, an Urban Lake in Upstate New YorkPeter Tobiessen; Elizabeth WheatLake and Reservoir Management1040-23810743-81411642000340 - 344Long and Short Term Effects of Waterfowl on Collins Lake, an Urban Lake in Upstate New York The effect of bird density on water quality parameters of Collins Lake was examined at three time scales: yearly, seasonally, and weekly. There was no relationship between bird sightings and either coliform bacteria or Secchi disc transparency on a seasonal or long-term (19 year) period. There was also no increase in spring chlorophyll levels over the 19 year period, even though the annual total bird sightings increased almost three times over that period. However, chlorophyll levels did increase during the ice-free season as shown by an almost doubling of fall chlorophyll levels between 1978 and 1997. Increased bird density is considered the most probable cause for these elevated fall chlorophyll levels. The increase in summer resident birds appeared to have a greater effect on chlorophyll levels than migratory birds. There was no observable effect of bird density on chlorophyll levels on a weekly basis, but the large number of other variables changing in the lake during the study period may obscure any trend on this time scale.
Preliminary Evaluation of Forced Air-Drying for Preserving Chlorophyll on Glass Fiber FiltersPaul J. Godfrey; Peter A. KerrLake and Reservoir Management1040-23810743-81411632000222 - 234Preliminary Evaluation of Forced Air-Drying for Preserving Chlorophyll on Glass Fiber Filters An alternative method of preserving filtered chlorophyll samples allows immediate filtration of samples by professional lake managers and volunteer monitors with inexpensive transfer to a laboratory. Using a simple forced air-drying device, samples can be preserved for two weeks and, perhaps, as long as 1-1/2 months without significant change in pigment levels. Filters may be sent by first class mail to a laboratory after wrapping the filters in aluminum foil. A series of 5 experiments was conducted to explore the parameters for maximum extension of the holding time. Results suggest that preserving filters by forced air-drying may be equivalent to other methods such as immediate analysis or freezing, and may be better under many conditions common to field sampling.
A Management Alternative for Lake ApopkaDaniel E. Canfield Jr.; Roger W. Bachmann; Mark V. HoyerLake and Reservoir Management1040-23810743-81411632000205 - 221A Management Alternative for Lake Apopka We examine the idea that whenever high levels of planktonic algae impair a lake, nutrient control is the first step to be taken regardless of what other management actions might be contemplated. Our example is Lake Apopka, a 12,500 ha, shallow (1.7 m), polymictic lake in central Florida. Prior to 1947, the lake was dominated by macrophytes, was reputed to have clear waters, and had a national reputation for its largemouth bass fishery. Following a hurricane in 1947, the lake switched to a turbid, algal state and the bass fishery is all but gone. For over 30 years, it was either implied or stated directly that nutrient enrichment from anthropogenic activities, especially farms along the north shore, was to blame for this change and the lack of macrophyte recovery. The current management plan is to remove the farm nutrient supply by purchasing the farms under the theory that this will lower the total phosphorus concentration in the water and thus restore the lake. We have developed the most probable phosphorus budgets for the lake based on the studies of others and have determined that a fluid mud layer that is frequently resuspended by the wind will lead to high internal loading and slow the drop in phosphorus concentration. The equilibrium phosphorus concentration will lie between 52 and 88 mg·m-3, so the lake will remain in its eutrophic state. We propose an alternative management plan using artificial reefs that will focus on restoring the largemouth bass fishery in the immediate future. This idea is attractive because bass fishing was the dominant use of this lake in the past, it can be accomplished without waiting for a change in trophic state, and it can produce results in a relatively short period of time.
Book ReviewOwen LindLake and Reservoir Management1040-23810743-81411632000248Book Review
Temporal Water Chemistry Trends (1967–1997) for a Sample (127) of Florida WaterbodiesJulia B. Terrell; David L. Watson; Mark V. Hoyer; Michael S. Allen; Daniel E. Canfield Jr.Lake and Reservoir Management1040-23810743-81411632000177 - 194Temporal Water Chemistry Trends (1967-1997) for a Sample (127) of Florida Waterbodies Total phosphorus, total nitrogen, total chlorophyll and Secchi visibility data from 127 Florida lakes across three time periods, Early (1967-1972), Middle (1979-1981), and Present (1996-1997) were compared using paired t tests and repeated measures analyses of variances. Although the population of Florida has increased 116% over the last 27 years, expected increases in lake concentrations of nutrients were not found. For this sample of lakes, total phosphorus concentrations decreased over a 30-year time period and total nitrogen concentrations showed no significant change. Secchi visibility, one of the simplest parameters to measure and easily understood by lake-users, also showed no significant change over time. The sample of lakes showed a significant but small increase in total chlorophyll concentrations. The increase was unexpected because total phosphorus concentrations decreased and total nitrogen concentrations stayed the same, suggesting that other factors were impacting total chlorophyll concentrations in this group of lakes. It is speculated that changes in color, fluctuating water levels, and increases in the amount of aquatic plant control over time may help explain some of the increases in total chlorophyll. Independent estimates of normal month-to-month and year-to-year temporal variance for Florida lakes were calculated using long-term Florida LAKEWATCH data (71 lakes, with greater than 4 years of monthly data) and compared to the variance among the Early, Middle, and Present time periods. Most of the differences detected among the time periods using statistical analyses were within calculated normal monthly temporal variance. Thus, increased nutrient concentrations or decreased water clarity, that is often speculated to occur with population growth and watershed development, have not been documented in this sample of Florida lakes.
Rehabilitation of Delavan Lake, WisconsinDale M. Robertson; Gerald L. Goddard; Daniel R. Helsel; Kevin L. MacKinnonLake and Reservoir Management1040-23810743-81411632000155 - 176Rehabilitation of Delavan Lake, Wisconsin A comprehensive rehabilitation plan was developed and implemented to shift Delavan Lake, Wisconsin, from a hypereutrophic to a mesotrophic condition. The plan was threefold: (1) reduce external phosphorus (P) loading by applying Best Management Practices in the watershed, enhance an existing wetland, and short-circuit the inflows through the lake, (2) reduce internal P loading by treating the sediments with alum and removing carp, and (3) rehabilitate the fishery by removing carp and bigmouth buffalo and adding piscivores (biomanipulation). The first and second parts of the plan met with only limited success. With only minor reductions in internal and external P loading, P concentrations in the lake returned to near pre-treatment concentrations. The intensive biomanipulation and resulting trophic cascade (increased piscivores, decreased planktivores, increased large zooplankton populations, and reduced phytoplankton populations) eliminated most of the original problems in the lake (blue-green algal blooms and limited water clarity). However, now there is extensive macrophyte growth and abundant filamentous algae. Without significantly reducing the sources of the problems (high P loading) in Delavan Lake, the increased water clarity may not last. With an improved understanding of the individual components of this rehabilitation program, better future management plans can be developed for Delavan Lake and other lakes and reservoirs with similar eutrophication problems.
Agricultural Best Management Practices and the Decline in Surface Water Total Phosphorus Concentrations in an Impounded Everglades MarshMichael J. MaceinaLake and Reservoir Management1040-23810743-81411632000235 - 247Agricultural Best Management Practices and the Decline in Surface Water Total Phosphorus Concentrations in an Impounded Everglades Marsh Agricultural Best Management Practices (BMPs) in the 290,000 ha Everglades Agricultural Area (EAA) resulted in a 55% reduction in phosphorus loading to the remnant Florida Everglades in 1996-98, exceeding the 25% load reduction mandated by law. Consonant with this, discharge total phosphorus concentrations (TP) declined from 173 ug·L-1 in the 1980s to 103 ug·L-1 during 1996-98. Although not mandatory until 1995, BMP activity started in the EAA in the mid-1980s. I analyzed 3,798 surface water TP samples collected from 1980 to 1999 in a 54,700 ha impounded Everglades marsh that received surface water inflows from the EAA to examine temporal changes in TP. A gradient of high (> 100 ug·L-1) to low (about 10 ug·L-1) TP existed from northern regions that received EAA discharge south to interior regions of the marsh. During the 1980s, higher TP concentrations extended further south into the marsh, but that process reversed in the 1990s. During the 1990s, wet climatic conditions occurred and TP was inversely correlated to water levels throughout the marsh. However in nearly all regions, TP declined between 1980 and 1999 after accounting for the effects of water levels. Marsh TP was correlated to inflow TP in the regions nearest to the discharge gates, and inflow TP declined from about 150 to 50 ug·L-1 with the implementation of BMPs. In addition, this marsh was kept essentially flooded for 18 years to increase water supply, but a more normal “wet-dry” regulation schedule went into effect in late 1980 that permitted drying of the marsh. Three droughts followed by reflooding occurred during the 1980s that caused short-term “TP spikes” in the surface water. Lower inflow TP and possible stabilization of phosphorus between the sediment and the water in the marsh after being kept artificially flooded for so long appeared related to the decline in TP. The establishment of BMPs in the EAA have been successful to help in part to achieve phosphorus reduction goals throughout the remaining Everglades.
Hypolimnetic Nitrate Treatment to Reduce Internal Phosphorus Loading in a Stratified LakeMartin Søndergaard; Erik Jeppesen; Jens Peder JensenLake and Reservoir Management1040-23810743-81411632000195 - 204Hypolimnetic Nitrate Treatment to Reduce Internal Phosphorus Loading in a Stratified Lake Nitrate [Ca(NO3)2] was added to the hypolimnion of eutrophic Lake Lyng (10 ha, maximum depth 7.6 m), Denmark, over a 2-year period to study the impact on sediment phosphorus release and to evaluate the potential of hypolimnetic nitrate dosing as a lake restoration method. Dissolved (1995) or granulated (1996) nitrate was added 10 to 11 times at a depth of 5 m during stratification. The total dose was 8 to 10 g N m-2 yr-1. Hypolimnetic nitrate concentration was <0.01 mg N L-1 in years without dosing (1994 and 1997), and reached 1.2 and 2.2 mg N·L-1 in treatment years, respectively. Maximum concentrations of dissolved inorganic phosphorus (DIP) in the hypolimnion were 1.6 to 2.9 mg P·L-1 in untreated years, but were reduced to 0.8 to 1.2 mg P·L-1 in treatment years. Correspondingly, total phosphorus (TP) accumulation in treatment years was 48-77% that of non-treatment years. Dissolved nitrate seemed to reduce TP concentrations more efficiently than granulated nitrate, which sank partly into the loose sediment, and led to lower nitrate as well as lower iron concentrations in the hypolimnion. Lower iron release and/or lower nitrate concentrations resulted from the use of dissolved nitrate, which seemed to reduce precipitation of phosphate with iron and left a larger proportion of particulate phosphorus in the hypolimnion. Ammonia concentrations were higher with nitrate addition, probably due to enhanced mineralization of organic sediment and nitrate ammonification. The results from Lake Lyng suggest that the potential of using nitrate as a lake restoration method in deep lakes suffering from internal loading needs further investigation.
Epiphytic Algae on Deep-Dwelling Bryophytes in Waldo Lake, OregonN. S. GeigerLake and Reservoir Management1040-23810743-81411612000100 - 107Epiphytic Algae on Deep-Dwelling Bryophytes in Waldo Lake, Oregon Benthic bryophyte samples that were retrieved in 1990 from depths of 45 m to 110 m in Waldo Lake were analyzed in 1999 for epiphytes. Rewetting of dried material, most of which was liverworts, indicated extensive colonization by filamentous green and blue-green algae, diatoms and aquatic fungi. Bulbocheate, Oedogonium and Stigonema were the three most common filamentous genera present at nearly each of the six sampling sites. Analysis of diatom associations following the oxidation of dried bryophyte-algae subsamples resulted in identification of 37 taxa within 15 genera of typically attached species. Most species were of the genera Eunotia, Pinnularia and Cymbella. These taxa appeared to be widely distributed on the bottom of the lake, at some stations as much as 30 m to 40 m below the lower depth of the photic zone.
Use of a Remote Operated Vehicle and Sonar to Characterize and Estimate the Distribution of Benthic Vegetation in Waldo Lake, OregonRandall A. JonesLake and Reservoir Management1040-23810743-81411612000108 - 113Use of a Remote Operated Vehicle and Sonar to Characterize and Estimate the Distribution of Benthic Vegetation in Waldo Lake, Oregon Bryophytes that occur in Waldo Lake, Oregon were video-documented and their distribution estimated with sonar. In August 1990, the in situ growth form of the plants was directly observed for the first time using a remote operated vehicle (ROV). Specific growth form of the plants ranged from relatively uniform stand heights (0.25 to 1.0 m) within patches to moderately isolated forms best described as twisted “windrows” or “whorls.” The diameter of the whorls ranged from approximately 0.25 to 0.75 m in diameter and from 5 to 15 m in length. The whorl form was typically in association with patch edges. Plants were found at depths of 128 m (the maximum depth of the lake) and to an upper depth limit of approximately 40 m. The maximum distribution of plants was estimated at 48.9% of the lake area. The use of direct ROV video observation, combined with the sonar, proved to be an acceptable first step in qualitatively describing plant growth and estimating benthic vegetation distribution within the lake.
Preliminary Observations of the Benthic Cyanobacteria of Waldo Lake and Their Potential Contribution to Lake ProductivityAlvin C. Johnson; Richard W. CastenholzLake and Reservoir Management1040-23810743-8141161200085 - 90Preliminary Observations of the Benthic Cyanobacteria of Waldo Lake and Their Potential Contribution to Lake Productivity Cyanobacteria (blue-green algae) dominate the benthic habitats of Waldo Lake. These photosynthetic microorganisms may be the principal contributors to overall primary production in the lake, although hard data are not yet available. The main biomass of cyanobacteria consists of filamentous, nitrogen-fixing forms, which also produce a yellow-brown, UV-screening pigment (scytonemin) in their extracellular sheaths. This pigment is probably a necessity under these conditions of extreme water clarity in which UV radiation penetrates well. In addition, a conspicuous feature at 1 m to 5 m depths, along much of the shoreline, are living “stromatolites” which resemble shelf-like rock formations, and appear to be formed primarily by the growth of cyanobacteria. Further studies are underway.
Deep-water Bryophytes From Waldo Lake, OregonDavid H. Wagner; John A. Christy; Douglas W. LarsonLake and Reservoir Management1040-23810743-8141161200091 - 99Deep-water Bryophytes From Waldo Lake, Oregon At least thirteen taxa of bryophytes occur between 40 and 128 m depth in Waldo Lake, Oregon. Many taxa exhibit morphological modification precluding positive identification below the level of genus. Liverworts comprise about 98% of the bryomass, the balance being pleurocarpous mosses with trace representation of acrocarps. Predominance of liverworts at extreme depth suggests that they are more viable than mosses under attenuated blue light. All liverworts except one are apparently aquatic forms of upland species. Two mosses are normally upland species, the rest aquatic. Red pigments in some liverwort taxa were maintained as deep as 70 m, but most lost pigment below 40 to 50 m. Sphagnum maintained red pigment as deep as 100 m. Although production of benthic plants would be expected to be exceedingly slow under conditions of low light, low temperatures, limited nutrient availability, and considerable hydrostatic pressure, new growth of 1.5 to 3 cm on liverwort stems approximates annual growth increments observed on upland plants.
Growth and Diet of Fish in Waldo Lake, OregonNicola L. Swanson; William J. Liss; Jeffrey S. Ziller; Mark G. Wade; Robert E. GresswellLake and Reservoir Management1040-23810743-81411612000133 - 143Growth and Diet of Fish in Waldo Lake, Oregon Waldo Lake, located in the Oregon Cascades, is considered to be one of the most dilute lakes in the world. Even with low nutrient concentrations and sparse populations of zooplankton, introduced fish in the lake are large in size and in good condition when compared to fish from other lakes. This apparent anomaly is due to the availability of benthic macroinvertebrates. Taxa found in the stomach contents offish captured in Waldo Lake consist primarily of Chironomidae larvae and pupae, Trichoptera larvae and pupae, amphipods, Ephemeroptera larvae, and Odonata larvae.
A History of Fish Management in Waldo Lake, OregonJeffrey S. Ziller; Mark G. WadeLake and Reservoir Management1040-23810743-81411612000144 - 148A History of Fish Management in Waldo Lake, Oregon Trout Oncorhynchus sp. and Salvelinus sp. were released into Waldo Lake beginning in 1889, although releases prior to 1938 are poorly documented. Trout releases were documented for most years between 1938 and 1990. Trout releases were discontinued after 1990. Brook trout are reproducing in the lake and are larger than the average size of brook trout in most lakes in the Oregon Cascade Range. Angling pressure appears to be light and angler catch-rate is poor except during autumn. Future management options include releasing additional fish into the lake, removing fish or leaving things the way they are.
Recent Changes in the Zooplankton Assemblage of Waldo Lake, OregonAllan Hayes Vogel; Judith LiLake and Reservoir Management1040-23810743-81411612000114 - 123Recent Changes in the Zooplankton Assemblage of Waldo Lake, Oregon Since 1969, two years after introductions of Mysis relicta, the species composition and total density of zooplankton in ultraoligotrophic Waldo Lake have undergone significant changes. During our study, spanning 1969-1998, taxa richness and zooplankter body size decreased. Zooplankton density increased by three orders of magnitude, from <1 m-3 to greater than 600 m-3. Hesperodiaptomus persisted from 1969 through 1998, and appears to be a major determinant in zooplankton dynamics. Rotifers, except Collotheca, were held to extremely low numbers, and cyclopoid copepods were eliminated. Bosminal longirostris, the only cladoceran which is presently common in the limnetic zone of this high altitude lake, exhibits daytime avoidance of the surface waters possibly due to high light intensities.
Waldo Lake MacroinvertebratesRobert L. Hoffman; William J. LissLake and Reservoir Management1040-23810743-81411612000124 - 132Waldo Lake Macroinvertebrates A total of 41 taxa was collected from nearshore and offshore habitats in Waldo Lake. The highest taxonomic diversity occurred in nearshore habitats which were structurally more complex and heterogenous than offshore habitats. The presence of 39 taxa (Hydridae excluded) in nearshore habitats varied by habitat-type and taxonomic group. Habitat-type was based on substrate-type, and the presence of taxa in nearshore habitats was partially related to the substrate preferences of taxa. A limited number of taxa (i.e., 11) were collected from offshore habitats, which was, in part, a reflection of the relatively homogenous organization and structure of the deeper, offshore habitats of the lake. The percentage of functional feeding groups did not vary much by habitat, and the majority of taxa (i.e., 53%) was classified as predators. Chironomids had the highest relative abundance of all taxa, accounting for 27% of taxa collected in nearshore benthic core samples and 40% of taxa collected in offshore Ekman dredge samples.
Thermal and Chemical Properties of Waldo Lake, OregonJohn SalinasLake and Reservoir Management1040-23810743-8141161200040 - 51Thermal and Chemical Properties of Waldo Lake, Oregon Thermal and chemical profiles were obtained