A DRAFT INDEX USING BENTHIC MACROINVERTEBRATES TO ASSESS BIOTIC INTEGRITY IN THE OHIO RIVER.

J.M. Applegate¹, P.C. Baumann², and E.B. Emery³. ¹The Ohio State University, School of Natural Resources, Columbus, Ohio 43210, ²United States Geological Survey, Columbus, Ohio 43210, ³Ohio River Valley Water Sanitation Commission, Cincinnati, Ohio 45228

Multimetric biological indices have been developed to facilitate the quantification of degradation of aquatic systems. Although they have traditionally been used to evaluate small to medium–sized streams, the Ohio River Fish Index (ORFIn) has recently been created to assess biotic integrity in the Ohio River. The goal of this project is to develop a multimetric index using benthic macroinvertebrates to assess Ohio River biological integrity. In September 1999 and 2000, Hester–Dendy multiplate samplers were set every 100 meters downstream of various industrial and municipal wastewater outfalls for 300 to 1000 meters, as well as at an upstream reference site. Metric values were plotted against distance downstream of each outfall to determine their response to a gradient of human disturbance. Differences between reference and outfall sites were also observed. Of the more than 60 metrics examined to determine which detect changes in biotic integrity, ten were selected as having the most potential. Scoring lines for these metrics, which include proportion dipterans, number of mayfly individuals, and proportion amphipods, were then developed and evaluated. Index evaluation in subsequent years, as well as comparison with the ORFIn will help determine the applicability of the draft index to the Ohio River.