Long-Term Effects of Thermal Discharges on Ohio River Fish Communities

We will present results from long-term fish surveys of the Ohio River that were conducted as part of the Ohio River Ecological Research Program. Annual studies are conducted to determine what, if any, effect thermal discharges have on the fish community. The approach uses traditional comparisons of species composition and catch rates from areas upstream of power plants and downstream of their discharges, comparisons that are supported by unique long-term data sets and application of community measures such as species richness, the modified Index of Well-Being, and the Ohio River Fish Index. Electrofishing from 1991 through 2010 from selected power plants will be used to demonstrate the response of fishes to the thermal discharges.  The relationships between the various fish community-level measures and water temperature, habitat, and river flow will also be described.  This program is unique in that the 20-year data set allows us to determine whether there are long-term changes to the fish communities downstream of the various power plants or whether any changes observed are simply short-term responses (e.g., avoidance) to seasonally high temperatures.