Twin Ports harbor Invaded

[Lee Borgersen]

        Invasive faucet snails confirmed in Twin Ports harbor

Sep 25, 2014


Tiny European faucet snails, known for carrying a waterfowl-killing parasite, have been confirmed in the lower St. Louis River and Twin Ports harbor.

  the bad news......
The snails, first found in Lake Superior in 2010 at a marina in Washburn, were found in the Twin Ports by a team from the Environmental Protection Agency’s Mid-Continent Ecology Lab in Duluth.

“This is a substantial range expansion for this harmful invertebrate,” said Doug Jensen, aquatic invasive species program coordinator with Minnesota Sea Grant in Duluth. “We’re asking anglers, boaters and waterfowl hunters within the estuary to be especially vigilant about cleaning their boats, waders and other gear before leaving water accesses. These tiny snails are sneaky.”

The EPA team that found the snails in the Twin Ports has been working to find the most effective ways to test for newly arrived invasive species. The samples were taken in 2012 but only confirmed as faucet snails in August, officials reported Thursday.

“The densest colonies are near Grassy Point and Barker’s Island,” said EPA research ecologist Anett Trebitz

Faucet snails host intestinal parasites that wreck the internal organs of snail-eating waterfowl. When faucet snails invade they often crowd out native invertebrates that are a key part of the food chain for fish and waterfowl.

The snails are believed to have been in north-central Minnesota’s Lake Winnibigoshish since about 2005, where they have been blamed for spreading a trematode parasite that is fatal for waterfowl, especially diving ducks. The snails were blamed for the death of thousands of scaup on Lake Winnibigoshish in 2008 and hundreds in each of several years since then.

“The snails are still there and they are still killing ducks in late fall,’’ said Perry Loegering, DNR area wildlife manager in Grand Rapids. “The more scaup we see on the lake, the more that die.”

Loegering said the snail has the potential to transmit the parasite to geese, diving ducks and other waterfowl, depending on where the waterfowl feed. There have been similar waterfowl die-offs along the Mississippi River near La Crosse, Wis., and in lakes near Sebeka, Minn., he said.

“We’ve picked up one dead mallard, and ring-necked ducks, that have died from the trematode,’’ he said, adding that it’s hard to tell faucet snails from others.

“It’s a rather nondescript, half-inch-long snail that looks a lot like our native snails and are hard to tell apart,’’ said Loegering, who has found faucet snails along the Mississippi River for several miles downstream from Lake Winnibigoshish.

Trebitz said the EPA team’s search in the St. Louis River estuary also found ongoing invasions of other invertebrates, including zebra mussels, New Zealand mudsnails, European valve snails, several aquatic worms and pea clams.



A faucet snail shell is seen atop a pencil eraser. Photo courtesy Minnesota Sea Grant


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