Anthropogenic alterations in soil chemistry (metals and pH) and their relationship to amphibian body size and abundance in New York State forests

Background/Question/Methods

Atmospheric deposition of acids and metals has serious deleterious effects on a variety biota in the northeastern region of the United States, particularly amphibians. Because of their moist skin, cutaneous respiration, and use of aquatic and terrestrial habitats, amphibians are highly susceptible to environmental pollution. Environmental toxicants such as trace metals are just one of the stressors that put populations in jeopardy. Other factors, such as soil pH act synergistically with toxic metals to create increased deleterious effects on individuals. The transport of metals and acids via atmospheric deposition into pristine areas could account for some amphibian declines. The objectives of this research were to determine if there were relationships between either soil pH or soil metal content and presence of salamander species or individual abundance at three undisturbed upland deciduous forests in upstate New York: Clausland Mountain, Private Residence, and Shaupeneak Ridge. In 2011, sites were visited after a rain event and surveyed for salamanders. Species and number of individuals were recorded. Soil samples were collected and tested for moisture content, pH, organic content, and metal concentrations. Metal analysis was performed using inductively coupled plasma mass spectrometry (ICP-MS) and cold vapor atomic absorption spectroscopy (Flow Injection Mercury System, FIMS).

Results/Conclusions

Soil pH did not differ between sites (pH ~5 per site). Soil metal concentrations varied greatly among sites and varied depending on metal. Clausland Mountain had the highest soil metal concentrations overall. Cadmium, copper, chromium, and zinc were significantly higher in Clausland Mountain soil compared to the other sites. Shaupeneak Ridge however, had the highest concentrations of arsenic (18.97 mg/kg) and lead (73.28 mg/kg). Lead concentrations at Shaupeneak Ridge were significantly higher (5x higher) than both of the other sites. Soil metal concentrations, with the exception of mercury, were the lowest at Private Residence. Salamanders were found at all three sites but species present and individual abundance varied. Plethodon cinereus were most abundant at Private Residence (n=24). Notophthalmus v. viridescens were most abundant at Shaupeneak Ridge (n=10). P. cinereus snout vent length (SVL) at Shaupeneak Ridge were significantly smaller than Private Residence but did not differ from Clausland Mountain, possibly because only 2 individuals were found at Clausland Mountain. N. v. viridescens SVL was significantly smaller at Shaupeneak Ridge compared to Private Residence. The results from this study suggest that salamander body size and abundance are negatively impacted by soil metal concentrations even at trace levels.