Lake Erie Nutrient Management Priorities Set at International Workshop
Don Scavia, a researcher whose work is funded in part by the National Centers for Coastal Ocean Science, presented results from his Lake Erie hypoxia ecological forecasting project. His presentation focused on phosphorus loading, climate influence on those loads, subsequent impacts on dissolved oxygen and harmful algal blooms, and best management practices to control nutrient runoff.
Despite decades of nutrient pollution runoff reductions, harmful algal blooms and hypoxia (deadly zones of insufficient oxygen) have intensified in Lake Erie, the southernmost and shallowest of the Great Lakes.
Dr. Scavia, from the University of Michigan, gave his presentation at the Lake Erie Ecosystem Priority Science Synthesis Workshop, sponsored by the Great Lakes International Joint Commission, and held from February 25-26, 2013 in Windsor, Ontario.
Models developed under the project suggest that current nutrient load targets may not be sufficient to reduce harmful algal blooms and hypoxia. Watershed managers need to consider decreasing the loads, especially the soluble reactive phosphorus (SRP) that can leach out of the watersheds emptying into the lake.
Refinement of loading by geographic area or watershed may also be necessary. Some watersheds may have mostly agriculture-derived phosphorus which builds up in the soil, so limiting the application of fertilizers may not immediately decrease the dissolved loads, because of phosphorus leaching from the soil. Other watersheds have more urban sources, so they may need to customize their approaches to manage each of them.
Compounding the problems are expected changes in rainfall and storms due to climate change, which make current best management practices inadequate. Future climate regimes may require stricter adherence to these practices, or even establish a whole new set of them.
The commission will consider these findings as they refine Lake Erie’s regional nutrient management strategy.