PARENT SESSION
Poster Session # 7: Restoration, Resource Management, and Conservation.
Monday, August 4 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.
Stressor identification with the ecosystem model AQUATOX, Release 2.
Wellman, Marjorie *,1, Norton, Susan1, Park, Richard2, Frithsen, Jeffrey1, 1 US Environmental Protection Agency, Washington, DC, USA2 Eco Modeling, Diamondhead, MS, USA
ABSTRACT- Increasingly, the regulatory, remediation and restoration actions taken to manage impaired environments are based on measurement and analysis of biotic communities. When an aquatic community has been identified as impaired, the cause of the impairment must be determined so that appropriate actions can be taken. The US Environmental Protection Agency's Stressor Identification (SI) Guidance (EPA 2000) describes a methodology for identifying the causes of observed impairments in aquatic systems. Stressor identification requires extensive knowledge on a variety of stressors as well as depth of knowledge on the mechanism, symptoms, and stressor-response relationships for specific stressors. AQUATOX is a process-based, time-varying, fate and effects simulation model that integrates aquatic ecology, chemical dynamics, bioaccumulation, and ecotoxicology. AQUATOX can be used to predict not only the environmental fate of nutrients, pesticides, and other chemicals in aquatic ecosystems, but also their direct and indirect effects on organisms. Time-varying process rates and limitations are provided for detailed analyses. Therefore, the AQUATOX model is a valuable tool for stressor identification, specifically to evaluate the relative importance of multiple stressors, provide ecologically plausible causal scenarios, and eliminate unlikely causes. Examples will include an application to Coralville Reservoir, Iowa, where model results indicated that pesticide runoff, not nutrient or organic enrichment, was the primary reason that largemouth bass were not present. Model results were supported by the recovery of bass in Coralville Reservoir after the banning of dieldrin.
Key words: stressor identification, AQUATOX, multiple stressors, ecosystem model