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Current ecological risk assessment methodologies have limited capacity to account for the spatial heterogeneity in Stressors and physical/chemical conditions characteristic of aquatic and estuarine ecosystems. The Shannon-Weaver index was utilized to construct spatial models of benthic macroinvertebrate biodiversity in Chesapeake Bay over several time periods between 1987–2001. These models were subsequently compared to monitoring data for sediment contaminant concentrations and physical/chemical water quality conditions. A series of GIS exercises demonstrated that low values for species diversity were associated with higher concentrations of a diverse array of contaminants as well as physical/chemical water quality conditions. Multivariate regression analysis among a range of contaminant and water quality variables accounted for up to 61% of the observed variation in benthic biodiversity. Collectively, these results demonstrate the numerous challenges for conducting ecologically relevant risk assessments at the ecosystem level, which can be partially ameliorated with quality monitoring data and geographic approaches to environmental assessment.
benthic, biodiversity, water quality, contaminant, ecological risk assessment, GIS
Senior Research Fellow, Pew Center on Global Climate Change, Arlington, VA