Effects of Chytrid and Carbaryl Exposure on Survival, Growth and Skin Peptide Defenses in Foothill Yellow-legged Frogs

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• 作者：Carlos Davidson ; Michael F. Benard ; H. Bradley Shaffer ; John M. Parker ; Chadrick O'Leary ; J. Michael Conlon ; Louise A. Rollins-Smith
• 刊名：Environmental Science & Technology
• 出版年：2007
• 出版时间：March 1, 2007
• 年：2007
• 卷：41
• 期：5
• 页码：1771 - 1776
• 全文大小：151K
• 年卷期：v.41,no.5(March 1, 2007)
• ISSN：1520-5851

文摘

Environmental contaminants and disease may synergisticallycontribute to amphibian population declines. Sub-lethallevels of contaminants can suppress amphibian immunedefenses and, thereby, may facilitate disease outbreaks. Weconducted laboratory experiments on newly metamorphosedfoothill yellow-legged frogs (Rana boylii) to determinewhether sublethal exposure to the pesticide carbaryl wouldincrease susceptibility to the pathogenic chytrid fungusBatrachochytrium dendrobatidis that is widely associatedwith amphibian declines. We examined the effect ofcarbaryl alone, chytrid alone, and interactions of the twoon individual survival, growth, and antimicrobial skin defenses.We found no effect of chytrid, carbaryl, or their interactionon survival. However, chytrid infection reduced growthby approximately one-half. This is the first report of suppressedgrowth in post-metamorphic amphibians due to infectionwith chytrid. Rana boylii skin peptides strongly inhibited chytridgrowth in vitro, which may explain why chytrid exposuredid not result in significant mortality. Skin peptide defenseswere significantly reduced after exposure to carbarylsuggesting that pesticides may inhibit this innate immunedefense and increase susceptibility to disease.