Zebra mussels invade last watershed
By Bob Gross
The Oakland Press
Posted February 24, 2006
Zebra mussels have been found and confirmed in what had been the only major Oakland County watershed without the aquatic invaders.
According to Michigan Sea Grant, zebra mussels are in Bush Lake in Holly, part of the Shiawassee River Watershed.
Sea Grant also has a recent report from Bald Eagle Lake in Brandon Township, part of the Flint River watershed. That 2006 report, which has not yet been confirmed, would bring the total number of lakes in Oakland County with zebra mussels to 47 - 25 in the Clinton watershed; 17 in the Huron; two each in the Rouge and Flint; and one in the Shiawassee, said Carol Swinehart, communications manager of Michigan Sea Grant in East Lansing,
Residents worry about invasive animals such as zebra mussels and their effect on the Shiawassee River ecosystem, "just as we're very concerned about invasive plant species and the potential impact those invasives would have on our plant species," said Nancy Strole, Springfield Township clerk, who has been active in preserving the Shiawassee River Corridor in northern Oakland County.
"Sure we're concerned, because we have such a diverse ecosystem here, and the potential impact on our waters could be significant," she said.
The Shiawassee watershed contains rare fens, wetlands with unique plant communities that rely on highly alkaline groundwater. The Shiawassee fens and other grassy wetlands in the corridor have been ranked by The Nature Conservancy, a national conservation group, as being of global significance.
The river winds through Springfield, Rose and Holly townships, passing through several lakes that would be devastated by zebra mussel infestations.
"It begins at Shiawassee Lake, goes north and feeds in to Davis Lake and Long Lake, and all of those lakes are very pristine," Strole said.
Zebra mussels are natives of the Caspian, Black and Azov seas in Asia. They probably got to this country in the ballast water of a sea-going ship. They were first discovered in the United States in 1986 in Lake St. Clair.
The first confirmed reports of the aquatic invaders in Oakland County were in 1993 in Cass, Loon and Walled lakes. Cass Lake is in the Clinton River watershed, Loon in the Huron River watershed and Walled Lake in the Rouge River watershed.
Tracie Beasley, stewardship director of the Clinton River Watershed Council in Rochester Hills, said she has collected zebra mussels from the Clinton at Riverside Park in Auburn Hills and from Paint Creek at Children's Park in Lake Orion.
"We're just starting to get our finger on the pulse of this," she said.
Sea Grant confirmed reports in 2005 from 23 inland lakes statewide. Zebra mussels are now present in 227 lakes in 53 of the state's 83 counties.
Zebra mussels are filter feeders. They remove tiny organisms from lake water, in effect cutting the bottom out of the food chain.
They also attach themselves to boats, docks and other solid objects; in some instances, they even smother native mussels by attaching themselves to their shells.
They also promote the growth of other organisms - such as aquatic weeds and algae - that can be harmful to the freshwater lake ecosystem. "When the water gets clearer than it used to be, then you can get a lot more algae growth," said Jo Latimore, watershed ecologist for the Huron River Watershed Council.
That's because more sunlight energy can get to the lake bottom, which means more plant growth, she said.
"Zebra mussels also take in everything, but some of the blue green algae, the zebra mussels don't want that, and they just pass it through," said Latimore.
Some blue-green algae produce microcystins, she said, a group of liver-specific toxins that have been indicted in some livestock and pet deaths from drinking lake water.
Zebra mussels, she said, can potentially change a lake system "from a normal healthy algae to some that might be harmful."
Researchers at the University of Wisconsin-Milwaukee found a link between zebra mussel infestations in Lake Michigan and problems with cladophora - a branching green algae - washing up in large mats and fouling Lake Michigan beaches in Wisconsin.
"Cladophora seems to be a Great Lakes problem," said Latimore. "We find it in inland lakes and we find it in the Huron River but usually in our inland lakes it's not a huge problem."
The pace of zebra mussels spreading through Oakland County appears to be slowing - there were no additional lakes reported with the mussels in 2004 - from a high of 10 in 1998.
But that could be deceiving, said Swinehart. Sea Grant, she said, relies on reports from concerned residents.
"We're at the mercy of those who submit reports," she said. "We don't have even a dozen people out there surveying on any kind of schedule. We have to rely on the hundreds, perhaps even thousands, of people who love their bodies of water."
Latimore said she believes awareness is high.
"A lot of the lake association types I've talked to are keeping a close eye, and those that don't have zebra mussels are really proud of that and are educating their homeowners about how to keep them out," she said.
One way to keep them out is to be especially scrupulous about cleaning boats and trailers that move from one body of water to another, said Swinehart.
Zebra mussel larvae attach themselves to boat hulls, trailers and other parts that might not be readily apparent - and can last up to three weeks out of the water.
Boaters, she said, need to be aware "particularly early in the season, as the larval form of the mussels are being reproduced. They are not detectable to the naked eye as a mussel."
Boaters might notice a grainy rough textured substance sticking to boat hulls, she said, "but you wouldn't know without submitting a sample to a lab that they were, in effect, zebra mussels."
Sea Grant recommends power washing, followed by a thorough drying out
"The precious jewels that we are so blessed with in Michigan are still vulnerable," said Swinehart. "If we want to keep them in the shape we've enjoyed in the past, we have to be diligent."