titlepeople sampling

Acton_watershed_map

Our main field site is Acton Lake, a eutrophic reservoir, and its watershed, which is dominated by row crop agriculture. Reservoirs are among the most heavily subsidized ecosystems on earth, owing to large watershed:lake area ratios. Reservoirs in agricultural areas, which are common in many areas (such as the Midwest US) are subject to high rates of soil erosion. Reservoirs thus receive large subsidies of water, sediment and nutrients, often in a very episodic manner depending on the timing and intensity of storms.

Acton Lake is a highly eutrophic reservoir in southwestern Ohio. Its watershed is large compared to lake surface area (~112X) and is ~90% agriculture (Knoll et al. 2003 ). Forest (9%) and urban areas (<1%) comprise relatively minor fractions. Since 1994, we have used a high-resolution sampling program to quantify sediment and nutrient inputs to the lake via its 3 largest inflow streams, which drain 86% of the watershed (Vanni et al. 2001, 2006a , 2011; Renwick et al. 2008). As expected, Acton Lake receives large nutrient and sediment subsidies, and exhibits elevated nutrients and phytoplankton. Gizzard shad are extremely abundant (Schaus et al. 1997; Vanni et al. 2005, 2006b ; Hale et al. 2008) and the zooplankton assemblage is usually Acton Lake sediment plumedominated by small species, primarily rotifers (Pollard et al. 1997; Bunnell et al. 2003). Phytoplankton biomass is dominated by cyanobacteria during summer (Schaus and Vanni 2000; Dickman et al. 2006; Vanni et al. 2011). Phytoplankton are often light-limited, especially after storms that deliver large amounts of sediments (Vanni et al. 2006a). When nutrients are limiting, phosphorus (P) is usually the limiting nutrient; nitrogen (N) rarely limits because of high nitrate inputs from the watershed (Vanni et al. 2006a,b).

***All manuscripts referenced above can be accessed on the "Publications" tab***