The Science Seminar Series: February 28, 2013
An Assessment of the Anthropogenic Affect of Bridges on Fish and Macroinvertebrate Assemblages
Charles W. Wright
Department of Biology
Valdosta State University
Time: 4:00 -5:00pm
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 anthropogenic practices allows the return of natural habitats that are likely to include more sensitive species. Recent conservation studies have suggested that sites of anthropogenic origins may serve as potential habitats for reestablishment of populations following a drought event. We examined fish and macroinvertebrate assemblages, and physiochemical factors associated with these assemblages, at 14 bridge sites involving first through fourth order streams. 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 only 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.