University of Wisconsin–Milwaukee

Laura L. Hunt

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Sep 28, 2010 
UWM leads inquiry into Bay health
Photo by Photo by Jim Waples
Retrieving a sample of oxygen-depleted sediment
Researchers retrieve a sample of oxygen-depleted sediment from the bottom of Green Bay.

The University of Wisconsin–Milwaukee (UWM) and several collaborating organizations were awarded more than $1.3 million to investigate the influence of land use and climate change on hypoxia in Lake Michigan’s Green Bay. The grant money will be given over four years by the National Oceanic and Atmospheric Administration (NOAA).

A monitoring buoy

Hypoxia, which occurs when there is not enough dissolved oxygen in the water to sustain aquatic life, has been a recurring problem in Green Bay for decades. Recent evidence suggests it could worsen, says Val Klump, the UWM researcher leading the study.

Hypoxia can occur naturally, but more often it results from human factors – agricultural or urban runoff, for example – that introduce excess nutrients into a body of water, stimulating large blooms of algae. When those algae die, bacteria decompose them, using up oxygen in the process. Low oxygen levels in turn can lead to “dead zones” and fish kills.

Long, shallow Green Bay is particularly susceptible to hypoxia because it receives about one-third of the total nutrients that drain from the land into Lake Michigan. Future changes in the region’s climate – predicted to include more precipitation and warmer summers – could further enhance hypoxia by increasing the amount of nutrients washing into Green Bay.

“How does a regional shift in climate affect ecological processes? That’s one of the big questions,” says Klump, a senior scientist and director of the Great Lakes WATER Institute at UWM’s School of Freshwater Sciences.

To find an answer, Klump and his collaborators will collect data on oxygen distribution in the bay and sources of nutrients, among other things. Then they’ll use that information to develop a model to predict how future changes in climate or land use will affect the situation. 

“The idea is to couple the watershed to the bay, and look at how the system works today and how it might change if, for example, the summer gets extended by a week or two, or agricultural practices change,” Klump says.

The study’s results will help inform management efforts to improve Green Bay’s water quality. Currently, the southern part of the bay is listed as “impaired” by the U.S. Environmental Protection Agency and designated as an Area of Concern by the International Joint Commission, in large part because of its high nutrient levels and low oxygen levels.

Collaborators on the Green Bay hypoxia project include other scientists from UWM and the University of Wisconsin–Green Bay, the University of Wisconsin–Madison, the Green Bay Metropolitan Sewerage District and the Wisconsin Department of Natural Resources.

The project’s funding comes through NOAA’s Coastal Hypoxia Research Program.