Files
Abstract
River regulation and development are the foremost problems threatening fishes and other aquatic biota in the Southeastern US. The operation of hydroelectric facilities can influence both habitat availability and environmental stability in downstream areas. I evaluated the relative influence of habitat structure and environmental stability on fish assemblage structure at unregulated and hydropower regulated reaches of the Flint River in southwest Georgia. Habitat availability was highly variable at the regulated reach due to large, daily fluctuations in discharge. Habitat-specific fish assemblages also differed between reaches with a greater number of species occupying similar habitat types at the unregulated reach, most notably in shallow, slow-flowing habitats. The similarity of species assemblages occupying similar habitats at the unregulated and regulated reach also was lowest in habitats with high variability in availability. These differences suggest that flow regulation, associated with hydropower operation, primarily affects riverine fish communities by decreasing environmental stability.