Airborne Agricultural Contaminants, Disease, and Amphibian Declines: Using Landscape-Scale Patterns to Evaluate the Severity of an Emerging Environmental ProblemEPA Grant Number: R830395
Title: Airborne Agricultural Contaminants, Disease, and Amphibian Declines: Using Landscape-Scale Patterns to Evaluate the Severity of an Emerging Environmental Problem
Investigators: Davidson, Carlos , Knapp, Roland A.
Institution: California State University - Sacramento , University of California - Santa Barbara
EPA Project Officer: Carleton, James N
Project Period: January 1, 2002 through December 31, 2003 (Extended to November 30, 2005)
Project Amount: $214,848
RFA: Futures Research in Natural Sciences (2001) RFA Text | Recipients Lists
Research Category: Land and Waste Management , Ecological Indicators/Assessment/Restoration , Futures , Hazardous Waste/Remediation
The effects of pesticides on aquatic ecosystems are likely to be far more complex and widespread than suggested by the results of acute toxicity tests, and these effects may constitute a serious emerging environmental problem. A possible example of this problem is the worldwide decline of amphibians, for which there is growing evidence that low levels of airborne pesticides may be factor, possibly through immune suppression and synergistic effects with disease.
Using recently available datasets that describe in unparalleled detail (i) the spatially-explicit historical pesticide use patterns in California's San Joaquin Valley, and (ii) the presence/absence of amphibians, presence/absence of amphibian disease outbreaks, and habitat characteristics at over 6,000 water bodies in the adjacent Sierra Nevada, the goal of our proposed research is to test the hypothesis that upwind pesticide use is a significant predictor of the distribution of amphibians or amphibian disease outbreaks. If this hypothesis is supported, we also will identify the particular pesticides or classes of pesticides responsible for the relationship.
Using pesticide application data compiled by the California Department of Pesticide Regulation, our measures of pesticide use upwind from the 6,000 water bodies will include (i) total amount of all pesticides applied (total weight of all active ingredients) from 1990-2000, (ii) total use of each of approximately 90 major classes of pesticides (organophosphates, carbamates, etc.) applied from 1990-2000, and (iii) total use of selected individual pesticides applied from 1990-2000. Statistical analysis will include univariate and multivariate (logistic regression, general additive models, and regression tress) approaches. Multivariate analyses will allow us to assess the importance of pesticide use after first accounting for the effects of other independent variables that may mask or confound the effects of pesticides (e.g., presence/absence of nonnative fish, water body depth, surface area, elevation, littoral zone and near-shore terrestrial substrate characteristics, water body isolation, latitude). Upon completion, our proposed study will provide the most comprehensive test to date of the hypothesis that airborne pesticides are associated with the decline of amphibians, and of the secondary hypothesis that these declines are the result of disease outbreaks facilitated by suppression of amphibian immune systems. If our research indicates that airborne pesticides are associated with the distribution of amphibians or disease outbreaks, our analyses are designed to identify the classes of pesticides or even the individual pesticides responsible for the association. These results would be critically important in guiding the development of additional regulations aimed at better protecting aquatic ecosystems and human health.