50.4 Thursday, Jan. 5 Shifts in an isolated wetland salamander community over 30 yrs: Has climate change altered wetland hydrology? SCOTT, DE*; METTS, BS; UGA/SREL, Aiken, SC; UGA/SREL, Aiken, SC firstname.lastname@example.org
Geographically isolated wetlands (GIW) constitute critically important habitat for many species; pond-breeding amphibians rely on GIW for larval development and recruitment of juveniles. Most GIW in the Southeast are seasonal, i.e., not continually filled with water, and amphibian recruitment success is determined largely by wetland hydroperiod (the amount of time a GIW holds water). Most pond-breeding amphibian species have adaptations to subsets of conditions along the hydroperiod continuum; i.e., there are ‘short-,’ ‘intermediate-,’ and ‘long-hydroperiod’ species. Climate change has the potential to exacerbate the increasingly serious problem of amphibian decline by inducing shifts in average hydroperiod, as well as “normal” pond filling and drying dates. Rainbow Bay (RB), a GIW on the Savannah River Site (SC), has been sampled daily for herpetofauna for 32 yrs, a record long enough to begin to examine relationships among environmental variables, amphibian population trends, and climate variability. Since 1978 the average hydroperiod at RB has decreased (F1,28 = 6.69, P = 0.01) and the average date of pond filling is later (F1,28 = 8.34, P = 0.007). During that time we observed a shift in community dominance from several longer hydroperiod salamander species (Ambystoma talpoideum, A. tigrinum, Notophthalmus viridescens) to a shorter hydroperiod species (A. opacum). Community changes appear to be related primarily to drought cycles and accompanying shortened hydroperiods, which differentially affect species’ juvenile recruitment. Changes in hydroperiod dynamics of GIW across the landscape are likely to influence local (individual wetland) population persistence, as well as metapopulation dynamics by altering exchange rates of amphibians among wetlands.