Stream surprises! An investigation into the drivers of stream salamander population dynamics

In the small streams of riparian forests, salamanders play an integral role in ecosystem functioning. Despite their ecological importance, however, little research has been undertaken to thoroughly understand the factors governing stream salamander population dynamics. Furthermore, salamanders are facing global declines due to intensifying environmental and anthropogenic stressors. To direct effective conservation strategies for stream salamander communities, we must holistically understand their population ecology. In this study, we investigated drivers of stream salamander populations by surveying aquatic salamander diversity, abundance, and larval body size at forested streams in Virginia’s Coastal Plain. We used statistical modeling to relate differences in these response variables to an array of potential drivers across microhabitat and watershed extents. We documented 3 species Eurycea cirrigera (98.5% of individuals), Desmognathus fuscus (1% of individuals), and Eurycea guttolineata (0.5% of individuals). For abundance, we found time of year, stream water volume, and proportion of the watershed composed of evergreen forest to be significant predictors. For larval size, we found temperature, stream water volume, phosphate concentration, and the presence of coarse woody debris to be significant predictors. Our results help inform conservation strategies by highlighting a lack of species diversity, the importance of protecting short stream hydroperiods and deciduous forest patches to maintain abundance, and the potential negative effects of warming water temperatures and increased phosphate concentrations on larval body size.