A Study of Invertebrates along a Gradient of Floodplains in the Altamaha River Watershed

Abstract

The objective of this on-going study is to develop a theoretical framework to explain the graded change of invertebrate assemblages in riverine floodplain wetlands from the headwaters to the lower river reaches. We predict that floodplains in the upper reaches of the watershed will have flood pulses linked to local storm events and will be short in duration, and thus invertebrate assemblages will be dominated largely by movements of opportunistic riverine or terrestrial organisms into the wetlands. Downstream communities will consist increasingly of obligate wetland invertebrates since inundation periods become longer and more predictable in the lower reaches of the watershed, allowing sufficient time for wetland communities to develop. To test this hypothesis, we are examining invertebrate populations at nine floodplain sites in the Oconee/Altamaha River Watershed along a continuum of streams and rivers from low to high discharge. Floodplain invertebrates are essential in modifying, storing and transporting organic matter in and between wetland and riverine systems. Unfortunately, the wetland habitats upon which these invertebrates depend are among Georgia’s most threatened. The information developed from this study will contribute towards informing management decisions affecting invertebrates and other animals in floodplains of the Southeast.