Quantifying the Impacts of Chemical Mixtures on Ecological Communities

EPA Grant Number: FP917132
Title: Quantifying the Impacts of Chemical Mixtures on Ecological Communities
Investigators: Erickson, Richard Arlin
Institution: Towson University
EPA Project Officer: Lee, Sonja
Project Period: September 1, 2010 through August 31, 2013
Project Amount: $111,000
RFA: STAR Graduate Fellowships (2010) RFA Text |  Recipients Lists
Research Category: Academic Fellowships , Fellowship - Pesticides and Toxic Substances


This study will test the overarching hypothesis that mixtures of toxicants impact ecological community structure by altering relationships among species. This hypothesis will be tested by using and comparing two frameworks for quantifying the effects of toxic chemicals and chemical mixtures in the environment: (1) a “pesticide-as-predator” framework, and (2) a community “resistance and resilience” framework.


Toxic chemicals occur ubiquitously within the environment and are one of many stressors that impact natural systems. However, our understanding of the impacts of these chemicals is based on single-species toxicity testing where each chemical is studied individually without consideration of other chemicals or ecological stressors. This project uses current ecological theory as a context for developing approaches to quantify the impact of toxicant mixtures in an ecologically meaningful way.


A field investigation of the impacts of the variety of pesticides on invertebrate community structure in multiple ephemeral lakes of the Southern High Plains will be conducted. In addition, a series of laboratory experiments will provide resolution of the direct and indirect effects of toxicant mixtures. The ecological frameworks will be investigated by integrating the field and laboratory studies through hierarchical modeling.

Expected Results:

In general, the field of environmental toxicology has developed with surprisingly little interaction with the field of ecology. Nevertheless, a variety of theoretical frameworks within ecology have been developed to understand how ecological communities are structured. I expect that these frameworks will offer insight into the ways toxicants alter interspecific relationships, and, ultimately, the structure of ecological communities. This would represent a significant conceptual advance for the field of environmental toxicology.

Potential to Further Environmental/Human Health Protection:

Adequate environmental protection depends on the ability to understand and quantify the potential impacts of anthropogenic factors (in particular, chemicals) in an ecologically relevant manner. Current understanding of the ecological relevance of toxicity data, however, is severely lacking. This project will bridge this gap in knowledge.

Supplemental Keywords:

ecological toxicology, ecotoxicology, community ecology, aquatic toxicology, pesticide, chemical mixtures,

Progress and Final Reports:

  • 2011
  • 2012
  • Final