In the Central Appalachians (USA), mountaintop-removal mining accompanied by valley fills often leads to streams with elevated specific conductivity (SC). Thus, the ionic composition of freshwaters in this region is hypothesized to be a driver of the distribution and abundance of freshwater taxa, including stream salamanders. We examined the association between SC and stream salamander populations by conducting salamander counts in 30 southeastern Kentucky streams across a continuous gradient of SC that ranged from 30 to 1966 μS/cm. We counted 2319 salamanders across 5 species and, using a hierarchical Bayesian version of the N-mixture model, found a negative association between SC and salamander occupancy rates. This finding was consistent across adults and larvae of the 5 species we examined. Furthermore, we found that most salamander species and life stages showed reduced abundances given occupancy at greater SC levels. For example, estimated mean abundance given occupancy of larval Southern Two-lined Salamanders (Eurycea cirrigera) was 67.69 (95% credible interval 48.31–98.25) ind/10 m at 250 μS/cm and 2.30 (95% credible interval 1.46–3.93) ind/10 m at 2000 μS/cm. The consistent negative association across all species and life stages supports the hypothesis that salamander distributions and abundances are negatively associated with elevated SC of streams in southeastern Kentucky, even though physical and chemical environmental attributes, such as forest cover within stream catchments, were correlated with SC. Restoration of streams affected by mountaintop-removal mining should focus on restoring the ionic compositions that naturally occur in this region.
Digital Object Identifier (DOI)
Funding for this project was provided by the Kentucky Academy of Science, University of Kentucky Tracy Farmer Institute for Sustainability and the Environment, University of Kentucky Appalachian Center, Eastern Kentucky University Division of Natural Areas, the Society for the Study of Amphibians and Reptiles, Foundation for the Conservation of Salamanders, the Society of Freshwater Science, and the McIntire-Stennis Research Program (accession number 1001968).
Supplemental material is available online at https://doi.org/10.1086/709688.
Hutton, Jacob M.; Price, Steven J.; Bonner, Simon J.; Richter, Stephen C.; and Barton, Christopher D., "Occupancy and Abundance of Stream Salamanders along a Specific Conductance Gradient" (2020). Forestry and Natural Resources Faculty Publications. 46.
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