, Volume 28, Issue 7, pp 717–731 | Cite as

Bioaccumulation of methylmercury in wood frogs and spotted salamanders in Vermont vernal pools

  • Steven D. FaccioEmail author
  • Kate L. Buckman
  • John D. Lloyd
  • Amanda N. Curtis
  • Vivien F. Taylor


Mercury (Hg) has accumulated in forested landscapes in the Northeastern U.S., and hotspots with enhanced deposition have been identified throughout the region. Due to a variety of favorable landscape characteristics, including relatively high dissolved organic carbon (DOC), fluctuating water levels, and low pH and dissolved oxygen, vernal pools provide ideal conditions for the conversion of Hg to its more toxic and bioavailable form, methylmercury (MeHg). Yet little is known about the concentrations, speciation, and bioavailability of Hg in vernal pools, or its bioaccumulation in vernal pool fauna and potential export into terrestrial systems. We investigated the role of forest cover type on the bioaccumulation of MeHg in wood frog (Lithobates sylvatica) and spotted salamander (Ambystoma maculatum) eggs, larvae, and adults, and investigated relationships among MeHg and water chemistry (pH, DOC). Water samples from pools located in coniferous stands had greater concentrations of THg and MeHg compared to deciduous pool water, and showed significant positive correlation to DOC (r = 0.683, P < 0.001) and correlated negatively with pH (r = −0.613, P < 0.001). Methylmercury levels in amphibian embryos were similar between the two species (L. sylvatica mean = 5.4 ng/g dw; A. maculatum mean = 3.5 ng/g dw). Concentrations of MeHg increased substantially in larvae, and were significantly greater in A. maculatum (mean = 237.6 ng/g ± 18.5 SE) than L. sylvatica larvae (62.5 ng/g ± 5.7 SE). Forest cover type did not explain variation in MeHg concentration among amphibian embryos or larvae. Methylmercury levels in adult tissue samples were significantly greater in A. maculatum (mean = 79.9 ng/g ± 8.9 SE) compared to L. sylvatica (mean = 47.7 ng/g ± 9.7 SE). This research demonstrates that vernal pools are important hotspots where amphibians bioaccumulate MeHg, which may then be transferred to terrestrial ecosystems. The abundance of amphibian larvae suggests they could be important bioindicators for monitoring MeHg loading and bioavailability.


Vernal pools Methylmercury Amphibians Lithobates sylvatica Ambystoma maculatum 



Thanks to Meghan Wilson, Ann Chalmers, and volunteers Rick Biddle and Patrick Mullins for providing field assistance. We’d also like to thank Celia Chen for providing lab support, and several private landowners for providing access to study sites. Two anonymous reviewers provided helpful insights that improved the final version of the manuscript. Funding was provided by the Northeastern States Research Cooperative and National Institute of Environmental Health Sciences P42ES007373-20.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical approval

All procedures performed in studies involving animals were in accordance with the ethical standards of the institution or practice at which the studies were conducted. This research was conducted under a protocol approved by Dartmouth College’s Institutional Animal Care and Use Committee.


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Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Vermont Center for EcostudiesNorwichUSA
  2. 2.Department of Biological SciencesDartmouth CollegeHanoverUSA
  3. 3.Program in Ecology, Evolution and Conservation BiologyUniversity of Illinois at Urbana-ChampaignUrbanaUSA
  4. 4.Department of Earth ScienceDartmouth CollegeHanoverUSA

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