Grantee Research Project Results

2003 Progress Report: Airborne Agricultural Contaminants, Disease, and Amphibian Declines: Using Landscape-Scale Patterns to Evaluate the Severity of an Emerging Environmental Problem

EPA 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: Chung, Serena
Project Period: January 1, 2002 through December 31, 2003 (Extended to November 30, 2005)
Project Period Covered by this Report: January 1, 2002 through December 31, 2003
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

Objective:

The objective of this research project is to test the hypothesis that upwind pesticide use is a significant predictor of the distribution of amphibians or amphibian disease outbreaks. We will study the declines of the mountain yellow-legged frog (Rana muscosa) in the California Sierra Nevada using recently available data sets that describe the spatially explicit historical pesticide use patterns in California's San Joaquin Valley. We also will study the presence/absence of amphibians, presence/absence of amphibian disease outbreaks, and habitat characteristics at more than 6,000 water bodies in the adjacent Sierra Nevada. If this hypothesis is supported, we also will identify the particular pesticides or classes of pesticides responsible for the relationship.

Progress Summary:

We have compiled all of the pesticide use data obtained from the California Department of Pesticide Regulation, completed error-checking of these data, mapped wind directions for the study area, and computed upwind pesticide use variables for all sites in the amphibian/fish/habitat data set (7,500 water bodies in Sequoia, Kings Canyon, and Yosemite National Parks and a portion of the John Muir Wilderness). Pesticide use variables include those describing the total amount of all pesticides applied (weight of active ingredients) and the total amount of each of approximately 90 major classes of pesticides. In addition, we have developed a number of additional variables that characterize landscape conditions that may influence the effect of pesticides on amphibian presence/absence. These include variables describing the aspect of the watershed below each water body, the number of lakes upstream of each water body, and the total area of lakes upstream of each water body. We also have completed error-checking of amphibian presence/absence and habitat data and developed a variable describing the disease status of amphibians at each water body based on field surveys at more than 1,500 water bodies conducted in 2002-2003.

Variables describing amphibian presence/absence, non-native fish presence/absence, upwind pesticide use, and habitat variables have now been combined into a single data set being used in preliminary model development aimed at testing the central question of whether upwind pesticide use is a significant predictor of amphibian presence/absence after accounting for effects of nonnative fish and habitat conditions.

Our results to date are preliminary and may change with subsequent refining of our analyses. Given that disclaimer, univariate analyses indicate that sites lacking R. muscosa do in fact have higher total upwind pesticide use than do sites where R. muscosa is present. Results from our preliminary generalized additive model of R. muscosa presence/absence as a function of total upwind pesticide use, non-native fish presence/absence, and habitat variables indicate that upwind pesticide use has a significant negative effect on frog presence/absence even after accounting for the significant effects of non-native fish and habitat variables. Currently, we are exploring these relationships in more detail to develop our final modeling approach.

Future Activities:

We will be exploring the relationships between upwind pesticide use and R. muscosa presence/absence in much more detail as we develop our final modeling approach. We also will be expanding these analyses to include testing the hypothesis that upwind pesticide use increases the probability of disease outbreaks in R. muscosa populations. Finally, we will be exploring methods of disentangling the independent effects of pesticide classes and individual pesticides on both R. muscosa presence/absence and disease prevalence.

Journal Articles:

No journal articles submitted with this report: View all 3 publications for this project

Supplemental Keywords:

agriculture, pesticides transport, air, water, ecological effects, amphibian decline, mountain yellow-legged frog, Rana muscosa, sensitive populations, pathogens, indicators, modeling, California, CA, EPA Region 9., RFA, Scientific Discipline, ENVIRONMENTAL MANAGEMENT, ECOSYSTEMS, Geographic Area, Ecosystem Protection/Environmental Exposure & Risk, Ecosystem/Assessment/Indicators, State, Ecological Effects - Environmental Exposure & Risk, Ecological Monitoring, Ecological Risk Assessment, Ecology and Ecosystems, Biology, Risk Assessment, aquatic ecosystem, ecological exposure, pesticide exposure, airborne agricultural contaminants, ecosystem assessment, aquatic habitat, chemical contaminants, immune dysfunction, ecological assessment, agrochemcial, lanscape scale patterns, aquatic ecology, California (CA), amphibian population, disease

Relevant Websites:

http://www.csus.edu/indiv/d/davidsonc/ Exit
http://www.msi.ucsb.edu/resrchrs/knapp/text/name.html Exit
http://www.mylfrog.com Exit

Progress and Final Reports:

Original Abstract

2002

2004

Final Report