LTREB Renewal: Response of a reservoir ecosystem to declining subsidies of nutrients and detritus

本研究以俄亥俄州西南部的一个景观为模型系统，探讨农业的变化如何影响河流和湖泊。在农业实践中观察到的变化包括保护性耕作的显著增加，减少化肥的使用，减少农场动物（特别是猪）。这些变化正在减少土壤沉积物和化学物质从农场流入河流的数量。该项目将量化这些变化沿着下游湖泊的后续响应。湖中藻类的数量一直在增加，因为水中较低的沉积物允许更多的阳光穿透。然而，据预测，随着营养供应的持续下降，湖中的藻类将随着时间的推移而减少。另一个预测是，由于沉积物输入量减少，普通的食沉积物的砂囊将减少。这些鱼将大量的营养物质从沉积物中回收到藻类中。因此，如果鱼类减少，藻类应该下降得更快。俄亥俄州正在发生的农业实践的变化也发生在整个美国，但缺乏有关湖泊和溪流的长期反应的信息。由于农业是河流和湖泊非点源沉积物和营养物污染的主要来源，该项目将为参与水质保护、可持续农业和渔业管理的决策者提供重要信息。此外，该项目将为本科生和研究生提供大量的教育机会，他们将积极参与研究的各个方面。最后，计划中的流域教育中心建成后将展示这项研究，并帮助教育公众了解陆地活动对水质的影响程度。

This research examines how changes in agriculture affect streams and lakes, using a landscape in southwestern Ohio as a model system. Observed changes in agricultural practices include a pronounced increase in conservation tillage, reduced fertilizer use, and fewer farm animals (especially hogs). These changes are reducing the amounts of soil sediment and chemicals that run off from farms into streams. This project will quantify these changes along with the subsequent responses of a downstream lake. The amount of algae in the lake has been increasing, because the lower sediment in the water has allowed more sunlight to penetrate. However, it is predicted that algae in the lake will decrease over time as the nutrient supply continues to decline. Another prediction is that the common sediment-eating gizzard shad will decline because of lower sediment inputs. These fish recycle large quantities of nutrients from the sediments to the algae. Therefore, if the fish decline, algae should decline even more rapidly. Changes in agricultural practices that are occurring in Ohio are also occurring throughout the United States, yet there is a lack of information on the long-term responses of 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 educational opportunities for undergraduate and graduate students, who will be actively engaged in all aspects of the research. Finally, a planned watershed education center, when completed, will showcase this research and help educate the general public on the extent to which activities on land affect water quality.