Spring 2005


A Stinkin' Mess

Heaps of algae, loads of questions

Despite much research, it’s not clear why massive mats of algae have been fouling Lake Michigan beaches in recent years. Suspects include increasing phosphorus, zebra mussels, lower lake levels, and other factors. Whatever the cause, getting rid of the ugly, foul-smelling stuff isn’t easy.

Those were the take-home messages from a public forum on the issue held Feb. 18 in Cleveland, Wis. The day-long event was sponsored by Wisconsin Sea Grant, the Department of Natural Resources and UW–Extension. About 100 people, including scientists, homeowners, beach managers and concerned citizens, filled an auditorium at Lakeshore Technical College.

Beach managers along Wisconsin's Lake Michigan shoreline said the algae is keeping visitors away. Several homeowners and members of citizens groups expressed considerable frustration about the unsightliness and odor of the algae, known as Cladophora. Scientists discussed what is known -- and the considerable amount not known -- about the problem.

Erika Jensen, an environmental scientist at the UW–Milwaukee Great Lakes WATER Institute, presented research showing that Cladophora often contains high levels of E. coli and other pathogens, and that it prolongs their survival.

Many scientists addressed the role phosphorous may play in promoting algae growth. Erica Young, a biologist at the UW–Milwaukee Great Lakes WATER Institute, was one of several scientists who presented research indicating that phosphorous already in the lake’s water and sediments, rather than new inputs, may be spurring Cladophora growth. Vicky Harris, UW Sea Grant water quality specialist, pointed out that roughly two-thirds of all phosphorous in the lake is harbored in the sediments and recycled each year. Even so, phosphorous input into the lake is the only factor that people can significantly control, Harris said.

Several scientists noted that zebra mussels have dramatically altered nutrient cycling in the lake by removing phosphorous from the water and concentrating it on the lake bottom where they live. The mussels also increase water clarity, allowing more light to reach Cladophora, and they provide a hard surface for Cladophora to grow on.

John Berges, a UW–Milwuaukee ­biologist, suggested other relevant factors might include changing wind patterns, water temperatures and currents, and lake levels.

People have tried many ways to control Cladophora since the 1950s, when it first became a problem on the Great Lakes. These have included removing it with machines, killing it with chemicals, speeding its decomposition with bacteria or fungi, and masking the odor with lime. However, these approaches have been too expensive, impractical, or even counterproductive where they have been tried, reported DNR Water Resource Management Specialist John Masterson.

Scientists at the DNR and the UW–Milwaukee WATER Institute are planning more research this summer to better understand the roles of phosphorous, zebra mussels, water clarity, temperature, wind and water currents, and other factors in producing excessive algae.

The proceedings of a Dec. 8 workshop at the WATER Institute for scientists, beach managers and policy makers at can be found at www.uwm.edu/Dept/GLWI/cladophora.



The Aquatic Sciences Center is the administrative home of the
University of Wisconsin Sea Grant Institute & University of Wisconsin Water Resources Institute.

©2011 University of Wisconsin Board of Regents