Impacts of climate change, human land use, and mercury contamination on Southern Appalachian Plethodontid salamanders
Date of Award
Doctor of Philosophy
Matthew J. Gray
Dave Buehler, Benjamin M. Fitzpatrick, John Drake
The Southern Appalachian Mountains are home to the greatest diversity of Plethodontid Salamanders in the world. The future for these salamanders is uncertain as globally amphibians have been experiencing significant population declines. We investigated the impact of habitat loss, chemical contaminants, and climate change on Plethodontid salamanders in northeastern Tennessee and southwestern Virginia. Four-toed salamanders (Hemidactylium scutatum) were negatively impacted by powerline right-of-way (ROW) mowing. Embryonic and larval survival significantly decreased in ROW after mowing and required up to 3 years of vegetation regrowth to reach post mowing survival. We also investigated mercury contamination in black-bellied salamanders (Desmognathus quadramaculatus) from Whitetop Mountain, Virginia. We found these salamanders to be contaminated with mercury levels equivalent to salamanders from point source pollution streams. Additionally, salamander from streams facing the prevailing wind direction had significantly greater levels of mercury contamination. To help land managers in planning long range habitat goals for the Mount Rogers National Recreation Area, we also developed salamander occupancy models based on parameters describing forest structure and composition. Elevation or other abiotic factors had a greater association to occupancy than many forest parameters. Lastly, to determine the influence of climate change on Mount Rogers Nation Recreation Area (MRNA) salamander distributions, we compared current distributions with those from the 1950s and 1990s and examined regional temperature changes since 1948. Plethodon welleri, a high elevation endemic, moved down slope since both the 1950s and 1990s. Plethodon yonahlossee expanded its range both up and down slope, but P. cylindraceus experienced range constrictions since the 1950s. No significant differences were observed for regional temperatures since 1948. We also modeled future salamander occupancy based on current mean temperature preferences. Using the Canadian Centre for Climate Modeling and Analysis Coupled Global Climate Model (CGCM) and the Hadley Centre for Climate Predication and Research (HAD) global circulation models with 2 different CO2 [carbon dioxide] emission projections, we projected the extirpation of P. welleri, D. organi, and Eurycea wilderae from Whitetop Mountain by 2070. Our results provide land managers with data necessary to better prepare for the challenges to maintain Plethodontid salamander populations.
Hamed, Michael Kevin, "Impacts of climate change, human land use, and mercury contamination on Southern Appalachian Plethodontid salamanders. " PhD diss., University of Tennessee, 2014.