Southern Two-Lined Salamander Diets in Urban and Forested Streams in Western Georgia

Abstract

Streams are heavily affected by watershed urbanization as increased stormwater runoff changes their physical and chemical composition. Benthic macroinvertebrate species richness has been consistently shown to decline with urbanization. Conversely, biomass of macroinvertebrates can increase with urban development. We examined the effect of such shifts in macroinvertebrate assemblages on the diet of larval Eurycea cirrigera (Southern Two-lined Salamanders). Salamanders have been documented to decrease in diversity in urban habitats; however, Southern Two-lined Salamander larvae which persist in urban streams (at lower densities) tend to grow larger than larvae in forested streams. Diet may play a role in these diversity and growth trends. We examined prey consumed by larval salamanders during spring, summer, and winter seasons across urban and forested watersheds. Prey diversity in salamander digestive tracts peaked during summer. We found Chironomidae (Diptera) larvae to be the most common prey item, followed by Ostracoda. Gastropoda were a common prey item during summer, which may be indicative of nutrient requirements of premetamorphic larvae. Overall, we observed minor differences in larval diet between urban and forested watersheds. A previous study within these same watersheds found that larvae in urban watersheds grew larger than those in forested watersheds, and the authors suggested prey availability may have contributed to that finding. The diet data we present here do not support such a hypothesis.