Stormwater basins are a commonly employed Best Management Practice designed to deal with the negative effects of runoff from impervious surfaces. They are ubiquitous in the landscape; yet the effect of these basins on faunal assemblages has not been investigated. Stormwater basins have the potential to influence the breeding distribution of anurans by being sources for some species and sinks for others. Our study aims to determine which species benefit from the existence of stormwater basins, which species are negatively impacted, and what variables are the best predictors of these effects. Thirty-six permanently ponded stormwater basins in southern New Jersey were monitored in 2008 for the presence of mating adults and anuran larvae by aural surveys, dip-netting and trapping. Interviews, visual encounters, dip-netting, and traps assessed fish presence. Water temperature, conductivity, and pH were measured throughout the growing season. A 100 foot buffer area surrounding the ponds was divided into managed and unmanaged grass and woody vegetation as well as impervious surface. Two connectivity metrics, distance to canopied corridor and percent of undeveloped upland within 500 meters were analyzed with ArcGIS.
Results/Conclusions
Fish were detected in 92% of the basins. Resistance to fish predation distinguished successful species, those with larvae present, from unsuccessful species, those with calling activity but no larval presence. Permanently ponded basins were sources for Bufo woodhousii fowleri, and Rana catesbeiana, and sinks for Pseudacris crucifer crucifer, Hyla versicolor, and R. clamitans.
Connectivity to and availability of terrestrial habitat were significant predictors of how many species mated at the basins. The number of species increased as access to and amount of quality terrestrial habitat increased. This suggests that placement of ponded basins near populations of threatened or endangered amphibians susceptible to fish predation is unadvisable. Additionally, as wet basins are sources for Rana catesbeiana, in areas where bullfrogs are invasive, basins will likely increase propagule pressure.
