Document Detail

Multiple stressors and amphibian declines: dual impacts of pesticides and fish on yellow-legged frogs.
MedLine Citation:
PMID:  17489262     Owner:  NLM     Status:  MEDLINE    
More than 40% of Earth's 5700+ amphibian species have undergone recent declines. Despite the likely involvement of multiple factors in driving these declines, most studies continue to focus on single stressors. In California (USA), separate studies have implicated either introduced fish or pesticides as causal agents. To date, however, no study has simultaneously evaluated the respective roles of these two potential stressors nor attempted to assess their relative importance, information critical for the development of effective conservation efforts and environmental policies. We examined the role and relative effect of fish and pesticides on the mountain yellow-legged frog (Rana muscosa) using unusually detailed data sets for a large portion of R. muscosa's historic range in California's Sierra Nevada. Habitat characteristics and presence/absence of R. muscosa and fish were quantified at each of 6831 sites during field surveys. Pesticide use upwind of each site was calculated from pesticide application records and predominant wind directions. Using generalized additive models, we found that, after accounting for habitat effects, the probability of R. muscosa presence was significantly reduced by both fish and pesticides, with the landscape-scale effect of pesticides much stronger than that of fish. The degree to which a site was sheltered from the predominant wind (and associated pesticides) was also a significant predictor of R. muscosa presence. Taken together, these results represent the strongest evidence to date that windborne pesticides are contributing to amphibian declines in pristine locations. Our results suggest that amphibian declines may have complex multi-factorial causes, and caution that single-factor studies that demonstrate the importance of one factor should not be used as evidence against the importance of other factors.
Carlos Davidson; Roland A Knapp
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Ecological applications : a publication of the Ecological Society of America     Volume:  17     ISSN:  1051-0761     ISO Abbreviation:  Ecol Appl     Publication Date:  2007 Mar 
Date Detail:
Created Date:  2007-05-10     Completed Date:  2007-06-06     Revised Date:  2007-12-03    
Medline Journal Info:
Nlm Unique ID:  9889808     Medline TA:  Ecol Appl     Country:  United States    
Other Details:
Languages:  eng     Pagination:  587-97     Citation Subset:  IM    
Environmental Studies Program, San Francisco State University, California 94132, USA.
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MeSH Terms
Anura / physiology*
Fishes / physiology*
Pesticides / toxicity*
Population Dynamics
Predatory Behavior / physiology
Water Pollutants, Chemical / toxicity
Grant Support
Reg. No./Substance:
0/Pesticides; 0/Water Pollutants, Chemical

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