Kain Morgan P, Hossack Blake R, Smalling Kelly L, Halstead Brian J, Grear Daniel A, Miller David A W, Adams Michael J, Backlin Adam R, Barichivich William J, Eagles-Smith Collin A, Emery Colleen, Fleming Jillian E, Fisher Robert N, Gallegos Elizabeth, Lor Duoa Jim, Kleeman Patrick M, Muths Erin, Pan Ty, Pearl Christopher A, Robinson Charles W, Rumrill Catilin, Tornabene Brian J, Waddle J Hardin, Walls Susan C, Grant Evan H Campbell
Pennsylvania State University, State College, PA, USA.
Eastern Ecological Science Center (Patuxent Wildlife Research Center), S.O. Conte Anadromous Fish Research Laboratory, U.S. Geological Survey, Turners Falls, MA, USA.
Sci Rep. 2025 May 19;15(1):17314. doi: 10.1038/s41598-025-99839-3.
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.
疾病，无论是单独出现还是与栖息地丧失和污染物等其他压力源共同作用，都会影响全球的野生动物种群。然而，压力源之间的相互作用以及它们如何影响种群统计学和种群数量，目前仍知之甚少。两栖类壶菌（蛙壶菌；Bd）是一种有时会致命的病原体，与全球两栖动物的种群数量下降和灭绝有关。实验室证据表明，像甲基汞（MeHg）这样普遍存在的污染物会降低两栖动物的活力和存活率，但在种群层面的影响仍不明确。我们通过非致命性采样来评估Bd和MeHg如何影响美国20个种群中幼年和成年两栖动物的存活率。随着Bd负荷的增加，几种物种的存活率下降，包括一些先前被认为对Bd有抗性的物种（如东部蝾螈[绿红东美螈]）。尽管我们对MeHg的采样不如对Bd的采样密集，但我们发现MeHg既能直接降低存活率，又能协同放大Bd感染的影响。对于山麓黄腿蛙（加州红腿蛙）的一个种群来说，估计MeHg导致的存活率降低超过了Bd。尽管不同种群和物种之间的影响差异很大，但我们的结果有助于阐明疾病和污染物协同作用的可能性，并强调识别和量化压力源之间相互作用在种群层面影响的复杂性。
