Zebra mussels have had their way since entering the Great Lakes in the 1980s, thought by experts to have arrived in dumped ballast water from ocean-going ships. First discovered in Lake St. Clair in 1988, the fingernail-size mollusk, native to the Caspian Sea, now inhabits all five Great Lakes and more than 600 inland waters in the United States, according to the U.S. Fish and Wildlife Service.
Wherever they land — transported by anglers, boaters or scuba divers who don’t wash aquatic vegetation and microscopic mussel larvae off their gear, trailers and boats — the population often blossoms. And once it does, the mussels clog freshwater intake pipes, cling to dock pilings and cluster heavily on anchors and chains.
Controlling their spread has been difficult, according to state and federal natural resource officials. Each mussel can produce one million eggs annually, and boater and angler education programs go only so far. But the battle to control zebra mussels could take a turn in coming years.
Marrone Bio Innovations, a California-based company, received U.S. Environmental Protection Agency approval in July last year for open-water use of a zebra mussel control product it named Zequanox. The dry compound is made from dead cells found in a common soil bacterium called Pseudomonas fluorescens. When mixed with water and injected into mussel colonies, it is ingested like food and kills by destroying the mussel’s digestive system.
Mike Toth, Zequanox sales manager with MBI, notes the product is best used for mussel control rather than eradication. It can be applied to mussel colonies on a piling or dock ladder. The company will come out and put up barriers to control its drift.
“It’s not impossible to treat an entire water body, but it isn’t necessarily feasible,” Toth says. “We haven’t treated lakeside property yet. But it is being tested with the idea that at some point that treatment would be available to a homeowner.”
MBI celebrated its first successful commercial open-water Zequanox application in September, 2014. The company was approached by the Minnesota Department of Natural Resources to conduct a treatment on Christmas Lake near Minneapolis, MN. Zequanox was applied to a 50-by- 60-foot containment area with an average depth of 2.5 feet, according to Toth. There were approximately 5,000 live mussels there before treatment. All were dead 11 days later.
“Two years ago we did a trial application in a deep quarry lake in Illinois. We revisited the same spot the following year and saw very little recolonization,” Toth shares. “That was promising, but it’s not something we can guarantee.”
MBI is working with the Michigan Department of Environmental Quality and federal agencies to test its use on bigger waters, like those of Lake Erie. Government officials say they are evaluating how to best use Zequanox in the Great Lakes.
“We know from field trials that the product has demonstrated efficacy (it kills zebra mussels),” says Sarah LeSage, the aquatic invasive species program coordinator for the MDEQ, which regulates its use.
“We are going to continue to work collaboratively with U.S. Geological Survey and other experts to investigate how we can use it in Michigan.”
To learn more, visit marronebioinnovations.com.
What You Should Know
• Zequanox is a registered pesticide in Michigan and other Great Lake states; registration is a requirement for use.
• Some home applications could require a state permit. Contact Rachel Matthews at the Michigan DEQ, matthewsr@michigan.gov, to learn if one is needed.
• Tests show Zequanox is not harmful to other species. It biodegrades and disappears within two weeks. Six hours is required for treatment. Recreational activities can resume immediately after application.
• For more information about Zequanox, contact Mike Toth at (651) 888-0843, or e-mail him at mtoth@marronebio.com.
Award-winning writer and BLUE Undercurrents columnist Howard Meyerson resides in Grand Rapids.
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