LTREB: Response of a Reservoir Ecosystem to Declining Subsidies of Nutrients and Detritus

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This research examines how changes in agricultural practices influence downstream streams and lakes, using a watershed in Ohio as a model system. Agricultural changes include a pronounced increase in conservation tillage, reduced fertilizer use and fewer farm animals. These changes are reducing the amounts of sediments (soil) and nutrients (phosphorus and nitrogen) running off from farms to streams. The research will quantify long-term declines in sediments and nutrients in streams, and the subsequent response of a downstream lake. It is predicted that algae in the lake will decrease as their nutrient supply declines, and that a common sediment-eating fish (the gizzard shad) will decline because of decreasing sediment inputs. These fish recycle large quantities of nutrients from sediments to algae in the water. Therefore, it is predicted that if the fish decline, algae will decline even further. Similar changes in agricultural practices are occurring throughout the US, yet there is a lack of data on the long-term responses of associated lakes and streams. Because agriculture is a major source of non-point sediment and nutrient pollution to streams and lakes, this project will provide critical information for decision-makers involved in water quality protection, sustainable agriculture and fisheries management. In addition the project will provide numerous opportunities for undergraduate and graduate students, who will be actively engaged in all aspects of the research.