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Tiny Snail, Big Trouble?

New Zeland Snail

EPA Discovers invasive New Zealand mudsnail in Minnesota and Wisconsin

Researchers from the U.S. Environmental Protection Agency's Mid-Continent Ecology Division have discovered an invasive species living in the waters of Lake Superior: the tiny New Zealand mudsnail (Potamopyrgus antipodarum).

The snail was discovered in sediments collected from Duluth Superior Harbor and the St. Louis River Estuary during a survey focused specifically on finding new invaders in Great Lakes harbors. EPA researchers found more than 100 New Zealand mudsnails.

Although only about the size of a peppercorn when fully grown, New Zealand mudsnails can mean big trouble. For starters, a snail does not need a partner to reproduce. New Zealand mudsnails breed asexually-essentially cloning themselves. Small populations can quickly explode.

In addition, by closing up its shell, a New Zealand mudsnail can survive for days out of water. Hitching a ride on the bottom of a boat, a pair of hip waders, or some fishing gear, snails can easily be moved accidentally from one body of water to the next. Once the New Zealand mudsnail is established in an area, it's hard to avoid new infestations.

"They have adapted so well in Western rivers that they have pushed out almost all of the native insects, snails, and other invertebrates that are important food for fish," says Doug Jensen, aquatic invasive species program coordinator for Minnesota Sea Grant. "More than 700,000 New Zealand mudsnails per square meter cover the bottoms of some rivers. That's like having 585,000 snails in your bathtub!"

Spreading the Word
State agencies in Minnesota and Wisconsin have launched communications campaigns prior to the beginning of boating and fishing seasons to alert people to look out for the snail, and take actions to reduce the chances of helping the snail spread.

On a larger scale, The EPA's Office of Research and Development has partnered with other organizations to establish an invasive species initiative. The goals of that program include using both conventional and advanced monitoring techniques in high-risk parts of the Great Lakes to predict what species may become a nuisance.

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