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 relationships 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. lacetrina) and amphiumas (Amphiuma means) among depression wetlands of the upper Atlantic Coastal Plain. The combined occurrence of sirens and amphiumas was positively correlated with hydroperiod length and negatively correlated with distance to the nearest intermittent aquatic habitat. Occurrences of individual species were negatively correlated 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 distribution in relation to other species, suggesting biological interactions may further limit the distribution of sirens and amphiumas among depression wetlands.