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Lake Invaders: Preventing MN’s Zebra Mussel Takeover

June 04, 2014 By Grace Putka, Macalester College

Today Minnesota 2020 continues a series of columns focusing on agricultural and biodiversity issues. This is part of a continuing collaboration with Macalester College's Geography Department and its students.

A menace is taking over Minnesota's famous lakes, and it’s no larger than your fingernail. This dime-sized mollusk called the zebra mussel is one of the most harmful invasive species in the United States.

Originally from Eastern Europe, the zebra mussel made its way to the US in the ballast water of large ships in the 1980's. In Minnesota, zebra mussels were first found in Duluth/Superior Harbor in 1989. According to a Minnesota Department of Natural Resources (DNR) report, the mollusks have invaded almost 200 bodies of water in over 20 counties. All evidence suggests that zebra mussels will keep spreading unless they are actively stopped, and it’s up to Minnesotans to stop them.

The Minnesota DNR defines zebra mussels as a "prohibited invasive species" because they pose a threat to ecosystems and humans in the state. Zebra mussels excessively filter the water they live in, producing unnaturally clear water that starves young fish and leads to overpopulation of aquatic plants. Unlike other freshwater mussels, they attach themselves to almost any hard surface they can find, including boats, docks, stones and other mollusks. Inspectors have found native species such as crayfish that have been killed by swarms of zebra mussels attaching to their shells and preventing them from moving around. Some native fish eat zebra mussels and their larvae, but zebra mussel populations still grow at a rate that hurts biodiversity and local ecosystems.

The damages of zebra mussels are not just environmental. Research suggests that in the United States they cause over a billion dollars of damage to pipes, drainage systems, intake valves and other infrastructure each year. They also give off an unpleasant odor and their sharp shells wash up on lakeshores and cut beachgoers.

Current DNR initiatives work to both stop the spread of zebra mussels to new bodies of water and to contain colonies where they exist. Boaters and fishers can be charged with a misdemeanor and fined up to $1000 for releasing live bait, failing to clean all plants and mussels off their boats before leaving a location, or transporting their boats without fully draining the motor and the ballast. Minnesota also has a system of volunteer inspectors who monitor their own lakes for signs of invasion and report back to the DNR once a year through the DNR website.

Unfortunately, education and prevention programs aren’t the only tactics the DNR has tried. In 2011, the DNR applied a pesticide, copper sulfate, to the waters of two lakes in Otter Tail and Douglas Counties in an attempt to prevent newly established zebra mussel colonies from taking over. Copper sulfate is a harsh broad-spectrum pesticide that kills aquatic life such as algae, plants and snails. In humans, copper sulfate can cause eye and skin irritation and leads to serious problems if ingested. But according to MPR, the pesticide failed to kill the zebra mussels. Both lakes are still infested.

Last summer, Minneapolis tried its own damage control scheme, funding a large-scale boat inspection program to try and prevent zebra mussels’ spread. The DNR has also stepped up prevention efforts statewide: for the summer of 2013, it staffed 150 invasive species inspectors and three dogs trained to sniff boats for zebra mussels. And there will be stepped up enforcement again this year.

These programs are certainly a step in the right direction. But the DNR estimates it would cost them $65 million to fund mandatory boat inspections at all of Minnesota’s lakes. That's more than 8 times their current budget for all projects related to aquatic invasive species.

People who enjoy Minnesota's waterways must take it upon themselves to stop the spread of zebra mussels and other aquatic invasive species. Initiatives at the state and local levels will never be effective without community support and individual efforts. The DNR does not have the budget to monitor all lakes and hold people accountable. So steeper fines likely aren’t enough. It’s up to the people who live, work and play near lakes to protect them from invaders.

The DNR provides information on how to avoid contaminating new lakes, from a hot water spraying to kill invisible zebra mussel larvae to properly flushing engines. Shoreline property owners should keep an eye on docks and shorelines to prevent one or two muscles from spreading.

If we as Minnesota's citizens make our lakes a priority and educate one another and ourselves, we can stop the spread of zebra mussels and save the native species and environments we love.

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