Independent and interactive effects of disease and methylmercury on demographic rates across multiple amphibian populations
Disease, alone or combined with other stressors such as habitat loss and contaminants, affects wildlife populations worldwide. However, interactions among stressors and how they affect demography and populations remain poorly understood. The amphibian chytrid fungus (Batrachochytrium dendrobatidis; Bd) is a sometimes-lethal pathogen linked with population declines and extirpations of amphibians globally. Laboratory evidence shows ubiquitous contaminants like methylmercury (MeHg) can reduce vigor and survival of amphibians, but population-level effects remain unclear. We used non-lethal sampling to assess how Bd and MeHg affected survival of juvenile and adult amphibians in 20 populations across the USA. Survival of several species declined with increasing Bd loads, including some species previously considered resistant to Bd (e.g., eastern newt [Notophthalmus viridescens]). Although our sampling for MeHg was less intensive than for Bd, we found MeHg can both directly reduce survival and synergistically magnify the effects of Bd infection. For a population of foothill yellow-legged frogs (Rana boylii), the estimated reduction in survival from MeHg exceeded that from Bd. Although effects varied widely among populations and species, our results help clarify the potential for synergistic effects of disease and contaminants and emphasize the complexity of identifying and quantifying the population-level effects of interactions among stressors.
Authors
- Michael J. Adams (ORCID: https://orcid.org/0000-0001-8844-042X)
- Brian J. Tornabene (ORCID: https://orcid.org/0000-0002-2348-3119)
- Caitlin T. Rumrill (ORCID: https://orcid.org/0000-0002-7799-4440)
- Susan C. Walls (ORCID: https://orcid.org/0000-0001-7391-9155)
- Blake R. Hossack (ORCID: https://orcid.org/0000-0001-7456-9564)
- Christopher A. Pearl (ORCID: https://orcid.org/0000-0003-2943-7321)
- Daniel A. Grear (ORCID: https://orcid.org/0000-0002-5478-1549)
- William J. Barichivich (ORCID: https://orcid.org/0000-0003-1103-6861)
- Kelly L. Smalling (ORCID: https://orcid.org/0000-0002-1214-4920)
- Robert N. Fisher (ORCID: https://orcid.org/0000-0002-2956-3240)
- Collin A. Eagles‐Smith (ORCID: https://orcid.org/0000-0003-1329-5285)
- Jill Fleming (ORCID: https://orcid.org/0000-0003-2570-914X)
- Brian J. Halstead (ORCID: https://orcid.org/0000-0002-5535-6528)
- J. Hardin Waddle (ORCID: https://orcid.org/0000-0003-1940-2133)
- Charles W. Robinson
- Patrick M. Kleeman (ORCID: https://orcid.org/0000-0001-6567-3239)
- Colleen Emery (ORCID: https://orcid.org/0000-0002-1208-3224)
- Adam R. Backlin (ORCID: https://orcid.org/0000-0001-5618-8426)
- Erin Muths
- Morgan P. Kain (ORCID: https://orcid.org/0000-0003-0605-7289)
- Evan H. Campbell Grant (ORCID: https://orcid.org/0000-0003-4401-6496)
- David A. Miller (ORCID: https://orcid.org/0000-0002-3011-3677)
- Elizabeth A. Gallegos (ORCID: https://orcid.org/0000-0002-8402-2631)
- Ty Pan
- Duoa Jim Lor
Institutions
- United States Geological Survey (US)
- Pennsylvania State University (US)
- Center Point (US)
- National Wildlife Health Center (US)
- Western Ecological Research Center
- U.S. Geological Survey, Wetland and Aquatic Research Center
- New Jersey Water Science Center
- Forest and Rangeland Ecosystem Science Center
- Fort Collins Science Center
- Northern Rocky Mountain Science Center
- University of Montana (US)
Publication Details
- Journal
- Scientific Reports
- Published
- 2025-05-19
- DOI
- https://doi.org/10.1038/s41598-025-99839-3
- Citations
- 2
- Primary Topic
- Amphibian and Reptile Biology
- Type
- article
- Field-Weighted Citation Impact
- 2.21
Funders
- U.S. Geological Survey