"Green Bay Hypoxia: Biogeochemical Dynamics, Watershed Inputs and Climate Change" ---
NOAA Coastal Hypoxia Research Program;
Presented for the Great Lakes Research Center Seminar Series
Presentedby Dr J. Val Klump: Director, Great Lakes WATER Institute and Professor, School of Freshwater Sciences, University of Wisconsin, Milwaukee Department;
Changing climate and its potential impact on hypoxia in Green Bay, Lake Michigan Green Bay, Lake Michigan, has a history of hyper-eutrophic conditions dating back nearly a century. Nutrient inputs from the Fox River in the southern end of the bay represent approximately one-third of the total nutrient loading to the Lake Michigan basin as a whole. The bay itself acts as an efficient particle trap, accumulating organic rich sediments that quickly become anaerobic, and seasonal hypoxia has been a common occurrence. Future climate scenarios project warmer and wetter conditions with shorter winters, reduced ice cover, increased winter runoff, increased frequency of heavy rainfall events, and an extended stratified period, all of which can impact hypoxia. Climate change may also trigger indirect consequences. A systematic southerly shift in the prevailing summer storm track in the Great Lakes region has altered circulation and mixing patterns in the Green Bay, resulting in an increase in the efficiency with which materials are trapped within the bay, and warmer bottom waters. The remedial action plan for Green Bay calls for a 40-50% reduction in nutrient and suspended sediment loadings. The goal of the current study is to estimate the efficacy of nutrient abatement strategies under a changing climate, using downscaled projections of regional climate change coupled to models of watershed runoff and the hydrodynamics and biogeochemistry of the bay.