Alternative Scenarios for Prairie Lake Communities: an Uncertain Future

Prairie lake communities are among the most vulnerable to anthropogenic change due to their low community complexity and high level of anthropogenic disturbance. There is concern that future changes in climate combined with agricultural influence will place excessive strain on these communities, potentially destabilizing food-webs or resulting in fish species extirpations. In this study, community composition and food-web data over a ten-year time series were used to quantify drivers of community composition. Species niche models were then applied to a 100-lake data set under current and future scenarios. Both food-web structure and top predator persistence were primarily influenced by lake morphometry, salinity, eutrophication and stocking regime. Higher trophic levels declined above 3 g/L TDS or 90 μg/L P and showed instability below these levels. The lakes were extremely sensitive to changes in climate and nutrient loading, showing substantial differences in potentially supported communities under contemporary, drought and warming scenarios. Drought was the primary driver of change in this system, indicating that changes in drought frequency or intensity are of greatest concern for future management.