The Relation of Fish Community Composition to Riparian Cover and Runoff Potential in the Minnesota River Basin, Minnesota and Iowa, 1997

The relation offish community composition to riparian cover and runoff potential was investigated in 20 streams in the Minnesota River Basin during the summer of 1997 as part of the U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program (fig.l). Analysis of variance statistics indicated significant differences in the composition of the fish community due to both riparian cover (wooded or open) and runoff potential (high or low). An Index of Biotic Integrity (IBI), species richness, and diversity were used to measure the community response and health. Fish communities in streams with significant wooded riparian cover had higher IBI scores, species richness, and diversity than streams with little wooded riparian cover. Streams with low runoff potential had higher IBI scores and species richness than streams with high runoff potential. IBI scores and species richness responded independently to riparian cover and runoff potential. Although both factors were important, riparian cover influenced fish community composition more than runoff potential in these streams, indicating that local factors (close to the stream) dominate landscape or basin-wide factors (Stauffer and others, 2000).