Methylmercury Concentrations More Strongly Associated With Trait Variation Than Food Web Position in Plethodontid...

Area of Science:

• Environmental Toxicology
• Ecotoxicology
• Amphibian Ecology

Background:

• Salamanders are crucial bioindicators for mercury (Hg) contamination in diverse ecosystems.
• They link lower trophic levels to higher predators, making them vital for food web dynamics.
• Understanding methylmercury (MeHg) drivers in salamanders is key for ecological risk assessment.

Purpose of the Study:

• To investigate factors influencing MeHg exposure in three New York salamander species.
• To compare MeHg levels across regions, habitat types, and color morphs.
• To establish baseline Hg data for future monitoring in New York forests.

Main Methods:

• Nonlethal tail samples from terrestrial (P. cinereus) and semiaquatic (E. bislineata, Desmognathus spp.) salamanders.
• Analysis of MeHg concentrations and stable isotopes (δ15N, δ13C) as diet and trophic proxies.
• Comparison of MeHg levels between Adirondack Mountains (ADK) and Finger Lakes National Forest (FLNF) regions.

Main Results:

• Salamander MeHg concentrations did not significantly differ by region for terrestrial species or one semiaquatic species.
• Diet and trophic position did not explain MeHg exposure.
• Semiaquatic salamanders had higher MeHg than terrestrial ones only in the FLNF.
• Striped P. cinereus morphs exhibited greater MeHg than unstriped morphs in the FLNF.
• New York salamander Hg concentrations were elevated compared to other known locations.

Conclusions:

• Regional differences and food web proxies (diet, trophic level) were not primary drivers of MeHg exposure in these New York salamanders.
• Snout-vent length was a predictor for MeHg in E. bislineata.
• Elevated Hg levels in New York salamanders highlight the need for ongoing monitoring and risk assessment.
• This study provides essential baseline data for assessing future Hg bioavailability in New York forest ecosystems.