Changes in land use, such as mountaintop removal mining with valley fills (MTR-VF), often results in headwater streams with elevated specific conductivity (SC). Stream salamanders appear to be particularly sensitive to elevated SC, as previous studies have shown occupancy and abundance decline consistently among all species and life stages as SC increases. Yet, the proximate mechanism responsible for the population declines in streams with elevated SC have eluded researchers. We sampled salamander assemblages across a continuous SC gradient (30–1966 μS/cm) in southeastern Kentucky and examined the diet of larval and adult salamanders to determine if the ratio of aquatic to terrestrial prey (autochthony), total prey volume, aquatic prey importance (Ix), and body condition are influenced by SC. Further, we asked if threshold points for each diet component were present along a gradient of SC. Larval salamanders experienced a 12–fold decline in autochthony at 153 μS/cm, a 4.2–fold decline in total prey volume at 100 μS/cm, a 2.2-fold decline in aquatic Ix at 135 μS/cm, and a rapid decline in body condition as SC increased. Adult salamanders experienced a 3–fold decline in autochthony at 382 μS/cm, no change in prey volumes, a 2-fold decline in aquatic Ix at 163 μS/cm, and a decline in body condition as SC increased. Our results indicate that SC indirectly affects stream salamander populations by changing the composition of diet, which suggests that food availability is a proximate mechanism that leads to reduced population occupancy, abundance, and persistence in streams with elevated SC.
Digital Object Identifier (DOI)
Funding for this project was provided by the following organizations: Kentucky Academy of Science (Marcia Athey Grant), Tracy Farmer Institute for Sustainability and the Environment, University of Kentucky (Karri Casner Environmental Sciences Fellowship), Appalachian Center, University of Kentucky (Eller Billings Summer Research Mini-Grant), Division of Natural Areas, Eastern Kentucky University (Grant-in-Aid of Student Research Program), the Society for the Study of Amphibians and Reptiles (Roger Conant Grants in Herpetology Program, Conservation of Amphibians and Reptiles), McIntire-Stennis Research Program (Accession Number 1001968), Foundation for the Conservation of Salamanders (Daniel M. Digiacomo Grant), and the Society of Freshwater Science (Graduate Student Conservation Award).
Hutton, Jacob M.; Price, Steven J.; Richter, Stephen C.; and Barton, Christopher D., "Diet Composition: A Proximate Mechanism Explaining Stream Salamander Declines in Surface Waters with Elevated Specific Conductivity" (2021). Forestry and Natural Resources Faculty Publications. 47.