Eutrophic Impoundment Research Articles

Artificial destratification effects on nitrogen and phosphorus dynamics in a eutrophic impoundment in the northern Great Plains.

To determine the influence of artificial destratification on nutrient variations in a small eutrophic impoundment, field monitoring and laboratory analyses were conducted in three consecutive summers (2010, 2011, and 2012). The impact of aeration among sampling locations and across the water column of nutrient concentrations, including total and dissolved inorganic nitrogen (N) and phosphorus (P) and water temperature and dissolved oxygen (DO) was evaluated under aerated and non-aerated conditions. Aeration eliminated thermal stratification and DO concentrations of bottom waters increased. Nutrients including soluble reactive phosphorus (SRP), total phosphorus (TP), and total nitrogen (TN) concentrations across the water column did not change significantly during aeration. Nevertheless, under aerated conditions, dissolved inorganic nutrients, TN, TP, and temperature were homogenously distributed throughout the water column as an effect of aeration. Results indicated that artificial destratification resuspended nutrients throughout the water column; however, it did not have a significant effect on nutrient concentrations in the water column, but SRP, TN, and TP concentrations did not reach to the recommended limit as needed by the North Dakota Department of Health requirements. Therefore, alternative aeration methods, for instance, hypolimnetic oxygenation or hypolimnetic aeration are recommended to control nutrient redistribution and/or further releases by existing aeration system.

Effects of Intermittent Artificial Circulation in Summer Months on Chlorophyll <i>a</i> Concentration in a Small Eutrophic Impoundment

Impact of artificial circulation on total algal biomass (as chlorophyll a integrated over depth) in a small eutrophic impoundment in the Northern Great Plains, was monitored over three consecutive summers. Chlorophyll a concentration and nutrient concentrations were measured at depths along water columns under aerated and non-aerated conditions at four sampling locations. Aeration destratified the water column, which resulted in homogenous chlorophyll a concentration throughout the water column and across the four sampling locations. The non-aeration resulted in concentration gradient along the water column at all sampling locations. Overall, the artificial circulation resulted in an overall reduction of chlorophyll a concentration along the water column and across sampling locations. Reduced chlorophyll a might be attributed to a shift in dominant phytoplankton species. For example, increased mixing by aeration may have favored dinoflagellates or green algae over cyanobacteria. In conclusion, the artificial circulation in this impoundment was effective in reducing total algal biomass.

Simulation model of phosphorus dynamics of an eutrophic impoundment – East Calcutta Wetlands, a Ramsar site in India

The East Calcutta Wetlands is one of the largest wastewater-fed aquaculture in the world. It is the aggregation of salt marshes, salt meadows and wastewater-fed ponds that receive wastewater from various small and large scale industries and urban settlements. The available nutrient supports the grazing food chain of the wetland ecosystem and agriculture around it. Eutrophication is caused by the imbalance between nutrient load and utilization by the autotrophs in the system. In this wetland, there has been a gradual decrease in the fish production for the last few decades. The physical and chemical conditions of the system are deteriorating continuously. Therefore, modelling of the system is felt to be the need of the hour to mitigate the problem of eutrophication and identify the important parameters that govern the system dynamics.Here, a dynamic model is constructed to study the phosphorus dynamics of the system. The five state variable includes; inorganic phosphorus (orthophosphate), phytoplankton, zooplankton, organic phosphorus and sediment. Important processes, like mineralization, uptake, grazing, predation, settling, resuspension and sorption are considered in the model. Field data are collected over two years and incorporated in the model as graph time function. Sensitivity analysis is performed and the model is calibrated using first set data followed by the validation process. Results indicate that the wetland is in hypereutrophic condition. The model result shows that the inorganic phosphorus of the system is mainly controlled by desorption of phosphorus from the sediments and mineralization during the premonsoon. The settling of organic phosphorus and adsorption of inorganic phosphorus are major regulating processes in the postmonsoon. In monsoon, resuspension process has important role in governing the phosphorus dynamics of the wetland. Moreover, allochthonous input of phosphorus is dominant over autochthonus input and controls the system dynamics. The input rate of inorganic phosphorus from outside is the system sensitive parameter. The paper discusses the present condition of the East Calcutta Wetlands and outlines some of the important management strategies that can be applied to alleviate the eutrophication problem of the wetland ecosystem.

Sperm motility and testicular histology as reproductive indicators inClarias gariepinusfrom an eutrophic impoundment, South Africa

Summary Testicular histology and sperm motility were studied as possible reproductive indicators of the reproductive potential for the wild, indigenous fish species (Clarias gariepinus) from an eutrophic impoundment, the Hartbeespoort Dam (HD) in South Africa. Parameters used as indicators include: GSI, testes histology and staging of the testes. Computer assisted sperm analysis (CASA), was used to assess sperm motility parameters including percent motile sperm (% MOT), velocity curvilinear (VCL μm s−1) and progression (PROG). These parameters were compared to C. gariepinus sampled at a reference site, the Marico Bosveld dam (MD). Water samples from both dams were analysed for metals and selected endocrine disrupting chemicals (EDCs). The water samples in the HD had notable high levels of selenium as well as nonylphenol and Di-n-Butyl phthalate. Macroscopic differences in the testes were found comparing the HD and MD. Fish from HD testes showed abnormalities regarding the interstitial tissue possibly due to proliferation of connective tissue. The CASA results showed no significant (P ≥ 0.05) differences for the% MOT of fish spermatozoa between HD and MD. The VCL and PROG of sperm had significant (P < 0.05) differences in fish between HD-LF, HD-HF and MD. It here fore seems that the increased environmental pollutants in the HD had an effect on reproductive status and sperm motility parameters of C. gariepinus when compared to the reference site MD.

Diatom response to the whole lake manipulation of a eutrophic urban impoundment

Diatoms typically dominate during April and May in Ford Lake, a eutrophic urban impoundment in southeastern Michigan, USA, whereas cyanobacteria dominate during summer. To alter this, whole lake experiments were conducted during 2006 and 2008 in alternation with control years 2005 and 2007. In experimental years, water was withdrawn from the hypolimnion during summer to destabilize the stratified water column, promote deeper mixing, and reduce anoxia. In 2006, withdrawals occurred over a 6-week period with three discrete intervals, releasing 3 × 105 m3 d−1 for the first and third intervals, and 1.5 × 105 m3 d−1 for the second. In 2008, withdrawal occurred continuously for 6 weeks at a rate of 3 × 105 m3 d−1. In control years, water was released only from the epilimnion. Nuisance cyanobacteria replaced diatoms in control years when the lake became thermally stratified. Diatom response to experimentally induced mixing was examined with focus on 2008 as a model for future management. Selective withdrawal of hypolimnetic water destabilized the water column and promoted diatom summer blooms. Diatom success was greatest in 2008, with abundance reaching 10 mm3 L−1 and persisting through spring and summer. Dominance peaks of diatoms were punctuated when Daphnia populations approached or exceeded 3 × 105 individuals m−2.

Managing Taste and Odor Problems in a Eutrophic Drinking Water Reservoir

ABSTRACT 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.

Dynamics of the Unexploited Walleye Population of Pymatuning Sanctuary, Pennsylvania, 1997–1998

Abstract Studies on the dynamics of unexploited fish populations are rare in the fisheries literature. The purpose of this research was to describe the dynamics of the unexploited population of walleyes Stizostedion vitreum of Pymatuning Sanctuary, a 530-ha eutrophic impoundment in northwestern Pennsylvania. We sampled walleyes with trap nets during the spring spawning runs in March and April 1997–1998. We estimated spawning adult abundance using the Schnabel multiple mark–recapture method and used walleye ages estimated from scales and otoliths for growth and mortality analyses. Population estimates of spawning adult walleyes were 29,693 and 23,298 fish in 1997 and 1998, respectively, or 56 and 44 fish/ha. The adult population was composed mostly of individuals greater than 500 mm total length. Compared with other populations, growth was excellent for juveniles but poor for adults. Average annual adult mortality was 32–41%, which is within the range of values reported for other exploited and unexploited ...

Long-term Changes in Parasite Population and Community Structure: A Case History

-A series of studies on the population and community ecology of several digenetic trematodes was begun in 1983 in a small, eutrophic impoundment in the Piedmont area of North Carolina. Initially, efforts were focused on the hemiurid trematode, Halipegus occidualis. Prevalence of this parasite in its snail intermediate host, Helisoma anceps, reached 60% in late June-early July, then dropped precipitously as the mature cohort of the snail host died-off. Over the next 13 yr, this annual pattern consistently repeated itself. Several years later, another pulmonate snail, Physa gyrina, colonized the pond. Either simultaneously, or closely thereafter, Halipegus eccentricus and two other species using P gyrina as an intermediate host also appeared. The trematode infracommunities in both hosts were examined; structuring forces were found not to be affected by competitive interactions among larval trematodes, but by a variety of factors, including snail vagility and size (age), microhabitat heterogeneity, distribution and temporal visitation patterns of definitive hosts, and the sequence of parasite recruitment mechanisms. Very few ( 7000 Helisoma anceps, whereas nearly 19% of all infections in 1181 P gyrina were multiple. Additional studies indicate that Halipegus occidualis cercariocysts do not remain infective for extended periods for second intermediate hosts (ostracods) as suggested in the older literature. Moreover, foraging ecology by odonate naiads is a significant factor in the recruitment and dispersion patterns of H. occidualis metacercariae. The long-term population ecology of H. occidualis and H. eccentricus was examined in mark-release-recapture studies of Rana clamitans, the definitive host. Halipegus occidualis prevalence and density were higher than those of H. eccentricus, although both were contagiously distributed in their frog definitive hosts. Halipegus occidualis exhibited large and rapid changes in density within frog hosts. Increases were probably because of the recruitment of contagiously distributed parasites from their third intermediate host, whereas declines in heavily infected definitive hosts were attributed to inflammation and tissue sloughing at the point of parasite attach-

THE EFFECTS OF ARTIFICIAL CIRCULATION ON A SMALL NORTHEASTERN IMPOUNDMENT1

ABSTRACT: Artificial circulation was applied at East Sidney Lake, a small, eutrophic impoundment in New York, to improve the water quality of the reservoir and tailwater. Treatment was successful at both reducing the stability of the reservoir and maintaining higher mean oxygen concentrations in the bottom waters. Discharge waters had lower metals and phosphorus concentrations during treatment years. However, vertical temperature differences, although minimal, were still sufficient to permit chemical stratification and some phosphorus release from the sediments. Frequent mixing events during periods of low stability, and runoff from storm events, also appeared to increase transport of phosphorus into the epilimnion. Overall, treatment did not result in decreases in algal populations or improvements in water clarity.

Changes in a hydropsychid guild downstream from a eutrophic impoundment

The structural changes induced by a small (0.015 km3) eutrophic hydropower impoundment, located in the middle Rio Duraton (northern Spain, Duero basin), on the downstream hydropsychid guild were studied by comparing physicochemical and biological characteristics of an upstream site with those of three downstream stations placed 0.2, 2.5 and 7.6 km below the dam. Species richness, species diversity and concentration of dominance were depressed downstream from the impoundment. Total biomass and density were also depressed at the station immediately below the dam. However, total density and biomass values were higher at sites further downstream than at the upstream reference site, presumably due to improved food supply and more available habitat. Abundances of Cheumatopsyche lepida, Hydropsyche sp. and H. pellucidula decreased significantly or completely disappeared at downstream sites. On the contrary, abundances of H. siltalai, H. exocellata and H. bulbifera increased downstream except at the station just below the dam. H. lobata was present at low densities at all sampling sites. H. pellucidula was the dominant species upstream, whereas H. siltalai became dominant downstream. The size structure of H. bulbifera, H. exocellata and H. siltalai experienced a modification below the impoundment as a probable consequence of the reduction in the number of competing hydropsychid species. It is concluded that the main physicochemical factors involved in the spatial variation of hydropsychid species were dissolved oxygen deficit and short-term flow fluctuations.

Comparison of Phosphorus Dynamics in Two Oklahoma Reservoirs and a Natural Lake Varying in Abiogenic Turbidity

The rate of phosphate uptake, the immediate fate of phosphate, and the potential rate of release of phosphate from dissolved phosphorus compounds in epilimnia of two reservoirs and one natural lake in northcentral Oklahoma were compared in the summer and in the late autumn. Sangre Isle Lake is a highly productive eutrophic impoundment, Sanborn Lake is a natural lake with low phytoplanktonic productivity, and Boomer Lake is an impoundment with modest productivity that is heavily affected by clay suspensoids. Although the uptake of phosphate (radiometrically determined) was rapid in each of these lakes in summer, the fate of phosphate in Boomer Lake differed from that of the others, with much of the phosphate sorbing to suspended silts and clays rather than biota (determined by isopycnic sedimentation). Recycling of phosphate from phosphomonoesters was greatest in Sangre Isle Lake, moderate in Sanborn Lake, but was undetectable in Boomer Lake. These findings suggest that high concentrations of clay suspensoids influence the epilimnetic P dynamics in reservoirs and lakes.

Fish parasitism in a new impoundment and differences upstream and downstream

The parasitic fish fauna in Guelph Lake, a four-year old impoundment, were compared with those in upstream and downstream localities. The lacustrine assemblage of the young mesotrophic to eutrophic impoundment was dominated by the cestodes, Ligula intestinalis and Proteocephalus ambloplites, and the nematode, Philometra sp. The acanthocephalan, Neoechinorhynchus saginatus, and the nematode, Rhabdacona cascadilla dominated the rheophilous assemblage of fish parasites, but the prevalence rate and intensity of R. cascadilla was significantly reduced downstream.

Impact of phosphorus removal at the Danbury, Connecticut sewage treatment plant on water quality in Lake Lillinonah

Lake Lillinonah is a highly eutrophic impoundment on the Housatonic River receiving 20 to 30% of its P load from domestic wastewaters from Danbury, Connecticut. In 1977 P removal from the domestic wastewater treatment plant was initiated, reducing the P load from the Danbury sewage treatment plant from 13700 to 6700 kg yr−1 in 1976 and 1977, respectively. The flows of the Housatonic River in 1976 and 1977 were also dissimilar; in 1977 about twice as much water entered Lake Lillinonah as in the former year.

Nitrogen fixation and the nitrogen budget of a eutrophic impoundment

In the eutrophic, nitrogen-limited impoundment Rietvlei Dam, the quantities of nitrogen fixed by three summer blooms of Anabaena circinalis varied from 1.1 to 24.5 t. The annual contribution of fixed nitrogen to the total annual inflow of combined nitrogen varied from 1.4 to 46.5%. Within the impoundment, soluble organic nitrogen forms a major part of the nitrogen pool and the processes of ammonification and nitrification appear to account for the production of large quantities of inorganic nitrogen from organic material. The fixation of atmospheric nitrogen is enhanced by low concentrations of combined nitrogen and high water temperatures. When these conditions persist, the contribution by nitrogen fixation to the total nitrogen budget can equal the annual nitrogen inflow via the feeder stream.

Eutrophication of a Tropical African Impoundment (Lake McIlwaine, Rhodesia)

Lake McIlwaine is an artificially eutrophic impoundment in tropical Africa, which has received sewage effluent since 1952, and has developed troublesome algal blooms. Rapid chemical changes have taken place since about 1960, and the lake is very much richer than other impoundments in the area. Chemical composition of the inflowing rivers shows that sewage effluent is responsible for this eutrophication, and rural runoff is not considered significant. The presence of an anaerobic hypolimnion is a doubtful index of eutrophication as this occurs in tropical lakes, regardless of trophic status. By contrast, the epilimnion of Lake McIlwaine shows permanent oxygen super-saturation, probably due to the high phytoplankton productivity. The lake has a high seasonal inflow and rapid replacement time, factors which could enhance the success of measures to reduce the inflow of sewage effluent.

Physico-Chemical Aspects of Lake McIlwaine (Rhodesia), A Eutrophic Tropical Impoundment

Lake McIlwaine is a tropical eutrophic impoundment in Rhodesia. The normal oxygen and temperature patterns are described, and the effect of flood water on these patterns is discussed. Several important chemical parameters are described, and the effects of lake-level fluctuations and stratification are outlined. There is a brief discussion on the effects of eutrophication in tropical lakes, and some indication is given of measures being taken to reduce nutrient input to Lake McIlwaine.