Muskegon lake
Aquatic life in Muskegon Lake in Michigan has made a dramatic recovery since the early 1970s, when communities and industries were forced to stop dumping sewage into the lake. Insects that are indicators of lake health are now found in much of the lake bottom, and pollution in bottom sediments has dropped significantly at many sites, according to new research published in the current edition of the Journal of Great Lakes Research.
Researchers who documented the change said completion of the Muskegon County Wastewater Management System in 1973 was largely responsible for the lake's improved condition. The density of all bottom-dwelling organisms across the lake doubled between 1972 and 1999, the density increased four-fold in some areas. Densities of some desirable species of benthos increased 57-fold from 1972 to 1999.
During the same period, pollution concentrations in some areas of the lake bottom decreased by as much as 69 percent. Those findings are significant because benthos are an indicator of a lake's health. In 1973, the lake bottom was dominated almost exclusively by pollution-tolerant benthos. Now there are more desirable and a greater variety of species that indicate good water quality.
Scientists also discovered numerous zebra mussels on the lake bottom. But they concluded that construction of the new sewage treatment plant did more to improve water quality and the population of benthos than did zebra mussels, which increase water clarity by filtering large volumes of water.
November 28, 2006 6:52 AM | Category: Lake