COMPARISON OF FLOW REGULATION EFFECTS ON FISH ASSEMBLAGES IN SHALLOW AND DEEP-WATER HABITATS IN THE TALLAPOOSA RIVER, ALABAMA

We measured species richness, diversity, and abundance of fish in both shallow and deep water areas in regulated and unregulated sections of the Tallapoosa River in Alabama from July 1990 through September 1992 to compare the effects of flow regulation on fish assemblages in shal low and deep water habitats. Flow regulation had a greater effect on s hallow water fish assemblages than on deep water fish assemblages. Spe cies richness and diversity of shallow water fishes were reduced below two hydroelectric dams compared with unmodified river segments, and w e attribute this to a reduction in species adapted to fluvial environm ents below the two dams. Additionally, the density of fish in shallow water areas of unregulated portions of the river was significantly (P< 0.05) higher than the density at most of the regulated sites. No reduc tions in species richness or diversity below the two dams were observe d for species inhabiting deep water areas. However, we collected a sig nificantly (P<0.05) higher number of catostomid species in the unmodif ied river sections compared to the flow-regulated sections.