A Multitiered Approach to Examining the Roles of Pesticides and Predation on Declining Amphibians

EPA Grant Number: FP916313
Title: A Multitiered Approach to Examining the Roles of Pesticides and Predation on Declining Amphibians
Investigators: Kerby, Jacob L.
Institution: University of California - Davis
EPA Project Officer: Lee, Sonja
Project Period: January 1, 2004 through December 31, 2006
Project Amount: $104,931
RFA: STAR Graduate Fellowships (2004) RFA Text |  Recipients Lists
Research Category: Academic Fellowships , Aquatic Ecosystems , Fellowship - Aquatic Ecology and Ecosystems


The objective of this research is to use an integrative approach to examine multiple mechanisms underlying the combined impacts of pesticides and predators on amphibians.


I propose to study interacting effects of pesticides and predation on amphibians at three different tiers. The first tier involves laboratory assays of the relative impacts of different pesticides on mortality and behaviors of different predators and prey when they are held apart. The next tier, still in controlled laboratory conditions, places both predators and prey together to observe possible interactions between pesticides and predatory or anti-predatory behaviors. The final tier observes several direct and indirect interactions that occur in multispecies communities at the mesocosm level. Information from the laboratory studies should help explain patterns that emerge in mesocosms that could and should yield insights on existing field patterns.

Understanding how sub-lethal levels of pesticides influence predator-prey interactions is vitally important in deciphering the potential causes of regional amphibian declines. Behavioral mechanisms are important in understanding ecological systems yet current U.S. Environmental Protection Agency standards do not address these pathways but instead seek to explain field patterns using laboratory tests done in the absence of other important stressors. The combination of behavioral and community ecology with toxicology will provide valuable insights. Behavioral ecologists can use toxicants with known effects to better understand proximate mechanisms underlying effects of behaviors on populations and communities. Studying effects of pollutants on predator-prey ecology also is becoming more important because anthropogenic impacts to the environment are so widespread that ecologists rarely encounter pristine reference sites. Ecotoxicology also benefits from this interaction by better understanding the key traits and species interactions that mitigate the bridge between toxicants, physiology, and impacts on natural communities. A divide currently exists between studies on the toxicological mechanisms of how contaminants act and the ecological mechanisms underlying risk assessments that operate on regional scales. A better understanding of individual behavior and interactions within a community provides a bridge between these two poles. This is perhaps no more evident than in the problem of worldwide amphibian declines where several mechanisms have been discovered and tested, and yet declines are difficult to attribute at larger scales. Because interactions often are complex, there are likely pieces of the puzzle missing at this intermediate scale. My project should help to bridge this gap.

Supplemental Keywords:

fellowship, amphibian, pesticide, LC50, behavior, predator, predation, amphibian declines, prey, toxicology, ecotoxicology, behavioral ecology, community ecology,, RFA, Scientific Discipline, ECOSYSTEMS, Ecosystem Protection/Environmental Exposure & Risk, Aquatic Ecosystems & Estuarine Research, amphibians, Aquatic Ecosystem, Aquatic Ecosystems, Environmental Monitoring, Ecological Risk Assessment, Ecology and Ecosystems, eutrophication, frogs, aquaculture, ecosystem monitoring, toxicity studies, toxicology, amphibian malformations, parasitic infestations, pesticides, predators, multiple stressors, environmental stress, wetland degradation

Relevant Websites:

http://www.des.ucdavis.edu/research/sihlab/profiles/kerby.htm Exit

2004 STAR Graduate Fellowship Conference Poster (PDF, 1p., 119KB, about PDF)

Progress and Final Reports:

  • 2004
  • 2005
  • Final