ECOLOGICAL CORRELATES OF ANURAN SPECIES RICHNESS IN TEMPORARY POOLS: A FIELD STUDY IN SOUTH CAROLINA, USA

Abstract

Identifying the factors that limit species distributions and maintain patterns of diversity is a major goal of temporary pond ecologists, and an important pursuit for conservation biologists. We used multiple regression analysis to identify ecological correlates of anuran species richness in twenty-one temporary pools within the Francis Marion National Forest, South Carolina. Analysis of data collected in 19961997 revealed that anuran richness was limited by the multiplicative effects of pool acidity, hydroperiod, and fish species richness. Anuran species richness declined with decreasing pH and hydroperiod, and with colonization by more species-rich assemblages of predatory fish. Two species of frog (Hyla cinerea and Rana grylio) and a newt (Notophthalmus viridescens) were excluded from the most acidic pools, and three anurans (Bufo quercicus, Pseudacris ornata, and R. capito) were limited by fish. Two large-bodied frogs with tadpoles that overwinter prior to metamorphosis (R. catesbeiana and R. virgatipes) were restricted to pools with longer hydroperiods, and R. capito was more likely to breed in large than in small ponds. The results suggest that anuran richness at our study site is controlled by different factors than in similar ponds in North Carolina, where hydroperiod and the densities of tadpoles and two species of salamander were important. Identifying mechanisms likely to affect local anuran species richness allowed us to predict how subtle anthropogenic stresses could cause declines in amphibians to begin, in a region where few have been reported.