In a paper published in the recent issue of Limnology and Oceanography, Orlando "Ace" Sarnelle, an associate professor in MSU's Department of Fisheries and Wildlife, and colleagues report that lakes that are home to zebra mussels have, on average, three times higher levels of a species of blue-green algae known as Microcystis.
Those same lakes also have about two times higher levels of microcystins, a toxin produced by the algae.
"If these blooms of blue-green algae are a common side effect of zebra mussel invasion, then hard-fought gains in the restoration of water quality may be undone," Sarnelle said. "Right now, it appears that the numbers of blooms in Michigan have been increasing and appear to be correlated with the spread of zebra mussels."
Initially, water samples were taken from nearly 100 inland lakes in Michigan's Lower Peninsula, ranging from Benzie County in the northwest to Oakland County in the southeast, that had established zebra mussel populations.
Follow-up experiments by Sarnelle and colleagues in west Michigan's Gull Lake showed that zebra mussels are indeed the cause of the increase in toxic algae.
There have been documented cases in which animals, including cattle and dogs, died after drinking water with high levels of microcystins. The toxin is also believed to be responsible for liver damage in humans.
Surprisingly, zebra mussels seem to have no effect on the amount of blue-green algae in lakes with high levels of phosphorus, a nutrient that builds up in lakes and other bodies of water as a result of erosion, farm run-off and human waste.
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Contact: Gisgie Dvila Gendreau
gendrea3@msu.edu
517-355-2281
Michigan State University
10-Mar-2004