Mechanisms driving Leptophlebia (Ephemeroptera) movements between river channels and floodplain wetlands

Linkages between river channels and floodplain wetlands are important for organisms in each habitat, but especially so for those species that use both habitats. Some species of mayflies (e.g., within Leptophlebidae and Siphlonuridae) undergo seasonal larval movements into seasonal floodplain habitats. These migrations have primarily been documented in northern temperate climates; however, there are no comprehensive studies located in lower latitudes. High densities of larval leptophlebians have been observed in Southeastern US floodplains but how they colonize and develop in these temporary habitats has not been established. We are investigating the life history of Leptophlebia mayflies and the mechanisms driving their movements from river channels into temporary floodplain wetlands in the Georgia Piedmont. We predict that, 1) mayflies actively migrate into floodplains rather than passively drift, 2) mayflies found in the wetlands have higher growth rates due to higher floodplain temperatures and abundance of high quality food resources, and 3) mayflies possess desiccation resistance to withstand short periods of drying. To test hypotheses we are examining Leptophlebia populations at floodplain wetland sites along the middle reaches of the Oconee River, GA. Results from this study will help determine the extent of ecotonal interactions between river channels and their floodplains.