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CONCEPTUAL MODELS AND METHODS TO GUIDE DIAGNOSTIC RESEARCH INTO CAUSES OF IMPAIRMENT TO AQUATIC ECOSYSTEMS
Citation:
Campbell, D E., B. H. Hill, N E. Detenbeck, K T. Ho, J C. Kurtz, R M. Burgess, V D. Engle, K T. Perez, M Pelletier, AND V M. Snarski. CONCEPTUAL MODELS AND METHODS TO GUIDE DIAGNOSTIC RESEARCH INTO CAUSES OF IMPAIRMENT TO AQUATIC ECOSYSTEMS. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-06/024 (NTIS PB2006-115526), 2006.
Impact/Purpose:
To describe methods and models for development of tools for diagnosing the causes of biological impairment within aquatic ecosystems
Description:
Methods and conceptual models to guide the development of tools for diagnosing the causes of biological impairment within aquatic ecosystems of the United States are described in this report. The conceptual models developed here address nutrients, suspended and bedded sediments (SABS), toxic chemicals and habitat alteration, the four classes of aquatic stressors that were identified as high priority areas for research by the Aquatic Stressors Framework. The report gives guidance for determining the causes of impairment that consists of a linked set of hierarchical, modular methods and models and a proposed classification scheme for aquatic ecosystems. In addition, an energy systems framework for developing causal network models of stressor action in aquatic ecosystems is presented in a series of text boxes as a parallel discussion. These two parallel approaches are brought together in the final section of the paper where detailed energy systems models of the main factors controlling the action of the four classes of aquatic stressors (nutrients, toxic chemicals, SABS, and altered habitats ) are described. A simple model of the three main factors (residence time of the pollutant, processing of the pollutant, and factors that change the relationship between stressor and response) controlling the action of the three classes of aquatic stressors that are pollutants (nutrients, toxic chemicals, and SABS ) was proposed as the linchpin needed to hold together the methods proposed to diagnose impairment to aquatic ecosystems of all kinds. In addition, this simple model was applied to identify the scale of effective management for a pollutant and to develop effective total maximum daily loads at the scale of watersheds as well as water bodies. Habitat alternation was recognized as a unique category of stress and a conceptual model for it was developed and related to the simple conceptual model controlling pollutants. Also, the connection between the need to classify aquatic ecosystems and the development of conceptual models is reported here. When proven and applied, the tools developed using these methods and conceptual models will simplify and improve the accuracy of water body evaluations currently being carried out by the states under Sections 305(b) and 303(d) of the Clean Water Act.