Influence of hydroperiod, isolation, and heterospecifics on the distribution of aquatic salamanders (siren and amphiuma) among depression wetlands

We used occurrence data gathered over a four-year period to assess relation ships among hydroperiod length (amount of time a wetland holds water during a year), wetland isolation from other aquatic habitats, and the occurrence of sirens (Siren intermedia and S. lacertina) and amphiumas (Amphiuma mean s) among depression wetlands of the upper Atlantic Coastal Plain. The combi ned occurrence of sirens and amphiumas was positively correlated with hydro period length and negatively correlated with distance to the nearest interm ittent aquatic habitat. Occurrences of individual species were negatively c orrelated with either distance to the nearest intermittent aquatic habitat or elevation difference between wetlands and the nearest permanent aquatic habitat. Siren lacertina showed higher than expected allopatric distributio n in relation to other species, suggesting biological interactions may furt her limit the distribution of sirens and amphiumas among depression wetland s.