Longitudinal variation in community structure of floodplain fishes of the Altamaha and Savannah river systems

Abstract

Many studies have examined whether longitudinal variation exists in stream fish communities. Despite the acknowledged importance of adjacent floodplains, no study has investigated longitudinal variation in fish communities in floodplain wetlands. I conducted research to determine if distinct fish communities exist between upper and lower floodplains reaches. I predicted that upper reach floodplains, where flooding is brief and intense, would be dominated by opportunistic fishes. In contrast, lower reach floodplains, which experience longer and more predictable flooding, would primarily consist of fishes specifically adapted to live and breed on the floodplain. To test this hypothesis, I examined fish populations along a gradient of discharge at floodplain sites along the lengths of the Oconee/Altamaha and Broad/Savannah river systems in eastern Georgia. Two unique communities were discovered related to stream reach, yet community utilization of reach-specific floodplains remains unclear. The results of this study should aid in wetland conservation and restoration projects.