In this study, I examined water chemistry of 31 Canadian Shield lakes in relation to catchment characteristics to test the hypothesis that Shield lakes with more marble may exhibit iron (Fe) deficiency and, hence, be more vulnerable to eutrophication. I performed a diatom-based paleolimnological reconstruction of one of these lakes (Heney Lake), which was subjected to anthropogenic stresses including a fish farm. Results suggest that the presence of marble influenced lake chemistry, including lowering the ratio of Fe: P. The reconstruction of historical P concentrations was not statistically possible but past Fe could be inferred, which no previous study has attempted. Certain eutrophication-associated diatom species suggest that logging and European settlement beginning in the early XXth century led to a slight increase in nutrient concentrations. However, a more important diatom species shift was likely related to climate change, as observed in other temperate lakes worldwide.

Changing lake conditions due to cyanobacterial harmful algal blooms (CyanoHABs) have prompted inconsistent and evolving management and recreational use of Southern Illinois University’s Campus Lake. The objective of this study was to address the need for understanding lake-user demographics, CyanoHAB and Campus Lake perception, and support for potential Campus Lake programs. I accomplish this by implementing and summarizing Lake-User and Student Questionnaires, applying an Experience Use History (EUH) method to categorize respondents, and utilizing university resources to understand the effects of environmental variables on perception of Campus Lake. Respondent demographics fit typical leisure participation, where most lake users were encountered walking/jogging. Students participating in the Campus Lake Sustainable Eco-Recreation program self-report a higher familiarity with lake water quality and CyanoHABs than non-participants. There was little evidence of Nature Deficit Disorder, and no difference in support for hypothetical management action options based on this factor. Backwards stepwise regression analysis of stated choice management action support for two hypothetical lake management plans resulted in a proscriptive outcome. EUH results modeled expected sociodemographic characteristics, and Beginners showed support for increasing recreation activity to support hypothetical lake management. Perceptions of Campus Lake water quality status were best correlated with visible algal growth, Temperature-Heat-Solar radiation-Wind index, and mean prior 24 hr relative humidity variables. This Campus Lake survey should be used to diversify lake accessibility and recreation programs targeted towards minority and special interest groups. Surveying of natural resource user perceptions, especially in the case of shifting quality, is a valuable tool to monitor and capitalize on public interest.

In response to concern that excessive macroalgal growth and accumulation was occurring in some inshore areas of Lake Macquarie, the distribution, abundance and seasonality of macroalgae was investigated in relation to nutrient input and power station cooling water. Macroalgal dry weight biomass was measured at ten sites on a monthly basis for two years, with an analysis of community structure conducted using Multi-Dimensional Scaling. The macroalgal community in Lake Macquarie was typical of those found in other New South Wales coastal lagoons, exhibiting considerable spatial and temporal variation. A close similarity was observed in macroalgal community structure at sites affected by urban nutrient input, these being characterised by a high biomass often attributable to only one or two species. These nuisance macroalgae were mostly green algae, which were almost entirely absent from other sites. Biomass at sites affected by urban nutrient input was generally within the range documented for eutrophic estuaries elsewhere. Analysis of macroalgal community structure showed no evidence of large-scale changes macroalgal communities attributable to the effects of power station cooling water except within 500m of the outfall. At sites affected by a 1-2??C temperature increase, community structure and the magnitude of the biomass were similar to sites deemed as being relatively free of human impact. A reduction in species diversity occurred only within the immediate discharge zone, where water temperatures were approximately 6??C above ambient temperatures. Excessive growth of nuisance macroalgal species was not observed at any of the sites influenced by power station cooling water. There were no distinct patterns in seasonality of macroalgal growth in this study, though the greatest biomass appeared to occur in spring. The irregular temporal variation in macroalgal growth suggests that the most significant factors affecting growth occur on a time scale of weeks to months. It is therefore likely nutrient input to the nearshore through surface runoff is an important influence on the distribution and abundance of macroalgae in Lake Macquarie. This emphasises the need to reduce nitrogen and phosphorus input from urban sources in Lake management.

In response to concern that excessive macroalgal growth and accumulation was occurring in some inshore areas of Lake Macquarie, the distribution, abundance and seasonality of macroalgae was investigated in relation to nutrient input and power station cooling water. Macroalgal dry weight biomass was measured at ten sites on a monthly basis for two years, with an analysis of community structure conducted using Multi-Dimensional Scaling. The macroalgal community in Lake Macquarie was typical of those found in other New South Wales coastal lagoons, exhibiting considerable spatial and temporal variation. A close similarity was observed in macroalgal community structure at sites affected by urban nutrient input, these being characterised by a high biomass often attributable to only one or two species. These nuisance macroalgae were mostly green algae, which were almost entirely absent from other sites. Biomass at sites affected by urban nutrient input was generally within the range documented for eutrophic estuaries elsewhere. Analysis of macroalgal community structure showed no evidence of large-scale changes macroalgal communities attributable to the effects of power station cooling water except within 500m of the outfall. At sites affected by a 1-2??C temperature increase, community structure and the magnitude of the biomass were similar to sites deemed as being relatively free of human impact. A reduction in species diversity occurred only within the immediate discharge zone, where water temperatures were approximately 6??C above ambient temperatures. Excessive growth of nuisance macroalgal species was not observed at any of the sites influenced by power station cooling water. There were no distinct patterns in seasonality of macroalgal growth in this study, though the greatest biomass appeared to occur in spring. The irregular temporal variation in macroalgal growth suggests that the most significant factors affecting growth occur on a time scale of weeks to months. It is therefore likely nutrient input to the nearshore through surface runoff is an important influence on the distribution and abundance of macroalgae in Lake Macquarie. This emphasises the need to reduce nitrogen and phosphorus input from urban sources in Lake management.

Eutrophication is one of the primary factors causing harmful cyanobacteria blooms in freshwater lakes; climate change such as warmer temperature can potentially further increase both frequency and intensity of blooms. This study investigated the long-term changes in water quality and summer phytoplankton assemblages in Oswego Lake, OR, in relation to lake management practices (e.g., hypolimnetic aeration and alum treatments), as well as climatic and regional meteorological conditions. Both water quality and phytoplankton assemblages were sampled biweekly during summer seasons between 2001 and 2013. The concentrations of total phosphorus (TP), soluble reactive phosphorus (SRP) and total nitrogen (TN) decreased 66%, 93% and 31%, respectively, in response to the hypolimnetic aeration and alum treatments since 2005. The results of summer phytoplankton assemblages showed a 62% reduction of cyanobacteria biovolume and a switch from cyanobacteria dominance (2001-2005) to diatom and chlorophyte dominance (2006-2013). Cluster analysis identified four statistically different groups of summer phytoplankton assemblages (denoted Groups 1-4). Nonmetric multidimensional scaling analysis indicated that the four groups were associated with different water quality conditions. Group 1 occurred prior to hypolimnetic aeration and was primarily comprised of cyanobacteria, associated with water conditions of high nutrients and high primary production. Group 2, dominated by cyanobacteria and chlorophytes, occurred between hypolimnetic aeration and alum surface application. Group 2 was associated with turbid water conditions. Group 3 was dominated by diatoms, occurring after alum surface application. Group 4 included R-strategist phytoplankton that quickly respond to environmental changes, occurring in the years following alum injection, drawdown and inflow alum treatment. Both Group 3 and 4 were associated with reduced nutrients in the lake. The results demonstrated a strong temporal relationship between the long-term changes in water quality and summer phytoplankton assemblages and the lake management practices. The Pacific Decadal Oscillation (PDO) index, an El-Niño-like pattern of Pacific climate variability, showed a statistically significant correlation with the summer phytoplankton dynamics, while the multivariate ENSO index (MEI) and regional meteorological variables (air temperature, rainfall, wind speed, wind direction and solar radiation) were not significantly related to the changes of phytoplankton communities during the study period. In conclusion, the study results suggest that the lake management practices had strong effects on both production and community compositions of phytoplankton, and suggest the need for a future study on large-scale climate impacts on lake ecosystems and best management practice.

Located in central Washington State, Banks Lake serves as an irrigation storage reservoir for the Columbia Basin Irrigation Project and is home to a diverse fisheries population. The current hydrologic management strategies used for Banks Lake have been chosen to serve two purposes: to adequately store and provide irrigation water for the Columbia Basin Irrigation Project and to maintain a healthy aquatic environment suitable for the growth and habitation of local flora and fauna. Increased needs for irrigation water within arid central Washington poses additional challenges to reservoir managers so that irrigation needs are met without damaging the present aquatic environment within Banks Lake. Future plans by the Washington Department of Ecology to use Banks Lake storage to replenish ground water reserves of the Odessa Subarea aquifer have required an investigation into how increased seasonal drawdown may affect fish growth, fish habitat and overall limnology of Banks Lake. The goal of this project is to produce a hydrodynamic and water quality model of Banks Lake that can predict the impacts of management strategies on the lake's water quality and the linkage of lake management to fish habitat.