Lake Health Improves, Problems Linger
Ann Arbor, MI — Environmental conditions in Muskegon Lake have improved since the early 1970s; however, levels of heavy metals in some areas of the lake remain high enough to be toxic to some of the animals that live in or bottom sediments.
Muskegon Lake is designated a Great Lakes Area of Concern due to severe degradation of water and habitat quality. The lake received industrial waste and sewage dating back to the lumber boom days in Michigan. While wastewater was diverted to treatment facilities beginning in 1973, few studies have assessed resulting responses in aquatic life.
"The number and type of invertebrate animals that live on or in the mud of a lake bottom are good indicators of overall environmental conditions," says Glenn Carter, a researcher at the Institute for Fisheries Research in Ann Arbor, MI. "Some animals can be found in very high numbers in areas that are subject to a great deal of pollution, whereas others require relatively pristine conditions."
In the case of Muskegon Lake, all invertebrates increased in abundance between 1972 and 1999. The number of species present in the lake also increased. Fingernail clams increased by 57 times over the 27-year period, while the percentage of aquatic worms decreased from 85% to 68%. Together these changes suggest that, while the lake remains enriched, conditions have greatly improved. Based on trends in specific animal types, these improvements were a response to waste diversion and not the filtering action of zebra mussels. Some problems still linger. There is an area of the lake near a storm sewer outfall where sediment concentrations of heavy metals like mercury and arsenic were high enough to have toxic effects in laboratory tests.
Original Publication Information
Results of this study "Status and Trends of Benthic Populations in a Coastal Drowned River Mouth Lake of Lake Michigan," are reported by Glenn S. Carter, Thomas F. Nalepa and Richard R. Rediske in the latest issue (Volume 32, No. 3, pp. 578-595) of the Journal of Great Lakes Research, published by the International Association for Great Lakes Research, 2006.
Contacts
For more information about the study, contact For more information about the study, contact Glenn Carter, Institute for Fisheries Research, The University of Michigan-Michigan Department of Natural Resources, Ann Arbor, MI. 48109-1084; carterg@umich.edu; (734) 663-3554.
For information about the Journal of Great Lakes Research, contact Marlene Evans, Editor, National Water Research Institute, 11 Innovation Boulevard, Saskatoon, SK, S7N 3H5, Canada; editor@iaglr.org; (608) 692-1076.
Links
Since 1967, IAGLR has served as the focal point for compiling and disseminating multidisciplinary knowledge on North America's Laurentian Great Lakes and other large lakes of the world and their watersheds. In part, IAGLR communicates this knowledge through publication of the Journal of Great Lakes Research, available to members in print and electronic form. A searchable archive of the journal is available online and includes the abstracts of articles from the journal's inception in 1975 through the most recent issue. In addition, complete articles are available to members who have signed up for an electronic subscription.