Evaluating thresholds in ecological responses to support policy and management actions

The Muskegon Watershed Research Initiative is a watershed-scale research program designed to provide the scientific underpinnings to guide management of an ecologically complex Great Lakes Watershed.  Land use, hydrology, water chemistry, and biological condition of streams, lakes, and wetlands were determined in a survey of approximately 250 habitats in the MRW.  These data, as well as regional data, were used to develop quantitative relationships linking valued ecological attributes, contaminants and habitat alterations (stressors), and the human activities (land use) in watersheds that were causing ecological alterations.  A multi-scaled analysis was used to support plausibility of causal relationships among ecological attributes using regression, structured equation modeling, and an integrated multi-model system simulating watershed behavior.  Thresholds in fish, invertebrate, and algal responses along a biological condition gradient were used to set biological condition benchmarks.  Thresholds in biological responses along phosphorus and fine sediment gradients were used to set management targets for these contaminants.  These management benchmarks, delineating state changes, were used to scientifically justify both protection and restoration targets in the watershed.