Abstract:
Anthropogenic impacts such as bridge sites can greatly alter established streambed morphology and associated ecology. At bridge sites, streams are often channelized approaching the site and deep pools are created at the bridge site causing ecological disturbances of fish and invertebrate assemblages. However, restoring channels and reducing negative construction practices allows the return of natural habitats that are likely to include more sensitive species. Recent conservation studies have suggested that sites of anthropogenic origin may serve as potential habitats for reestablishment of populations following a drought event. This study examined fish and macroinvertebrate assemblages, and physiochemical factors associated with these assemblages at 14 bridge sites involving first through fourth order streams in the Suwannee River Basin of south Georgia. Fish assemblages were least diverse upstream of bridge sites, most diverse at bridge sites, and intermediate downstream of bridge sites. Macroinvertebrate assemblages did not exhibit as distinctive a pattern as did fish assemblages. Upstream macroinvertebrate assemblages were less diverse than bridge site and downstream assemblages, a pattern that was disrupted for the bridge site by third order stream data. The results from this study suggest that bridge sites, if properly engineered, can serve as valuable refuges for reestablishing fish and macroinvertebrate assemblages up and down stream after events such as the severe drought that impacted south Georgia in 2011.