Disproportionate Importance of Edge Habitat for Ecosystem Functoning in Deep Oligotrophic Lakes

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Disproportionate importance of edge habitat for ecosystem functioning in deep oligotrophic lakesStephanie E. Hampton, University of IdahoNSF Starter Grant (0528531), 3 August 2005Human activities greatly alter many aspects of lakeshores; in particular, nutrients from fertilizers and sewage can encourage nuisance algae, and tree removal can decrease shading as well as reduce the number of insects that fall to the water surface where they are eaten by lake animals. While the lakeshore may constitute a relatively tiny area of the lake disturbed by humans, this nearshore area frequently may be the most critical habitat for breeding and feeding by fish and other animals. Here the importance of nearshore environments will be evaluated through examination of naturally occurring stable isotopes in tissues from lake animals and plants; carbon isotopes can indicate whether growth is mainly supported by nearshore or open water food resources, and nitrogen isotopes relate to an organism's position in the "food chain". Stable isotopes can also help differentiate among different nutrient pollutants that fuel growth of nuisance algae, such that managers can more effectively target monitoring and control. Disturbance to the shoreline can affect ecosystem functioning long before the rest of the lake appears polluted. Managers increasingly call for controls on nearshore pollution, although lake-wide consequences of localized disturbances are not yet well understood. This research will provide critical information on the role of nearshore environments in structuring plant and animal communities and help prioritize management and conservation efforts in lakes.