UW-Milwaukee researchers inform L. Michigan management with help of a GLOS buoy
How much phosphorus should flow into Lake Michigan? This question means millions for the economy around the lake and has huge implications for its underwater ecosystem. And researchers at the University of Wisconsin-Milwaukee led by Professor Harvey Bootsma are working to help answer that question with the help of a GLOS buoy.
Phosphorus finds its way into the water from lawns, the urban environment, and farm fields. Once there it meets with some important organisms which have a large say in the health of the lake and those around it: plankton, mussels, and certain kinds of algae.
Plankton thrive on phosphorus and support large portions of the food web. Invasive quagga and zebra mussels that entered the lake in the 1980’s eat the plankton, oftentimes starving bigger creatures who depend on a supply of plankton-eating prey. When phosphorus is dumped into the water, some types of algae grow excessively and wash onshore in big, stinking heaps.
Essentially, more phosphorus means more plankton, and more plankton means more food for those important bigger creatures like walleye and salmon that are experiencing food shortages. These fish bring thousands of anglers and millions of dollars to the region. But more phosphorus also means more of certain kinds of algae that can be problematic, sometimes creating human health hazards.
Answering the phosphorus question means understanding how the chemical travels through the lake and between organisms. To create a thriving lake ecosystem, managers have to understand where, why, and how phosphorus makes an impact, and the best way to do this is with a mathematical model. But for a great model, you need great data. And this is where researcher Joe Fillingham, working with Dr. Bootsma, set to work.
The team collected data on water temperature, current, and weather from the nearshore Atwater Park buoy and combined that with data from the Lake Express, a high-speed ferry that travels between Michigan and Wisconsin. Next, they used this data to structure and feed the model which was then able to accurately depict some complex relationships in the nearshore environment. For example, the model indicates that the amount of nuisance algae would be much less were there no quagga mussels in the nearshore zone.
The model has recently been applied to help the Wisconsin Department of Natural Resources and Milwaukee Metropolitan Sewerage District understand the water quality impact of a nearby wastewater treatment plant. And next, the lab will be working to incorporate the model into a larger one for all of Lake Michigan, in the hopes of determining a phosphorus loading rate that is best for health of the lake.
Additional support for the project came from the Milwaukee Metropolitan Sewerage District and the National Science Foundation.
A research crew works with the Atwater Park buoy just off the Milwaukee shoreline. Photos courtesy of UW-Milwaukee and Harvey Bootsma