Decision analysis and exploratory modeling in Lake Erie ecosystem management.

摘要

The Lake Erie setting involves important decisions in the areas of nutrient, fisheries, and habitat management that impact ecosystem health and human well-being. These decisions involve multiple stakeholders with conflicting priorities; they are complex, multi-jurisdictional, and involve uncertain outcomes. This research takes the view that better ecosystem management requires more than clearer goals or better basic science. We use and develop theory and techniques of decision analysis to evaluate reasonable actions to protect and restore the Lake Erie ecosystem.; The first portion of this work focuses on value elicitation because successful ecosystem management requires that time first be spent focusing on what we want. In the area of nutrient management, we carry out a systematic elicitation of stakeholder preferences, and an investigation of the degree to which different phosphorus-loading policies might satisfy ecosystem objectives. Results show that there are potential benefits to changing the historical policy of reducing phosphorus loading to Lake Erie. We also develop a methodological improvement that uses a Bayesian method to quantify and correct scale compatibility bias in multiattribute tradeoff weighting.; The second portion of this work turns from value elicitation to linking alternatives to outcomes, recognizing that much of the work required for successful decision analysis involves estimating impacts. An exploratory modeling approach is used to link land use to habitat to fish productivity in Ohio Lake Erie tributaries. First, we carry out a regionalization analysis in which we develop regressions that link landscape features in Ohio to the parameters of the hydrologic model IHACRES in order to predict stream flow. Second, these regressions are used to predict streamflow change in response to watershed scale reductions in forest cover, Finally, changes in streamflow are linked to survival of larval walleye that hatch in Ohio tributaries, building on previous research that showed that higher flows reduce survival. Results quantify the reductions in forest cover, consequent increases in watershed runoff, and consequent reduction in walleye larval survival. This landscape-habitat-fish productivity linkage is significant in that it goes beyond physical effects of watershed change to link to aquatic habitat and biota.