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Great Lakes Article:

Zebra mussels can't take the cold
Or the lack of calcium in Chequamegon Bay
By Claudia Curran
The Daily Press
08/01/03


It appears that zebra mussels accidentally introduced into Chequamegon Bay in 1998 haven't been able to survive and reproduce, judging from recent zebra mussel survey results.

Mild winters in 1998, 1999 and 2000 influenced a blossoming of zebra mussels in the Duluth-Superior harbor, but those same winters haven't seemed to affect Chequamegon Bay, said Gary Czypinski, U.S. Fish and Wildlife Service biologist and fishery technician.

The primary reason for the absence of the mussel may be mineral-related.

"We think it's due to a lack of calcium in the water," Czypinski said, adding that cold-water temperatures might also be a factor.

One of the first times Czypinski heard of zebra mussels being sighted in Chequamegon Bay was from an angler who fished off of Ashland's ore dock and snagged a piece of wood with a clump of zebra mussels attached.

Before the angler made the report, a zebra mussel-infested barge from Michigan came into Chequamegon Bay in 1998 - accidentally introducing several hundred exotic mussels into area waters, according to a report of the U.S. Fish and Wildlife Service's Ashland Fisheries Resource Office.

The Chequamegon Bay Zebra Mussel Task Force has monitored waters around the Bayfield Peninsula for the exotic mussel since 1999.

Only one dead adult mussel was sighted during a 2001 task force survey.

The mussel, found near an Ashland waterfront park boat landing and close to the Xcel Energy waterfront plant discharge area, could have fallen off of a boat's hull and into the water, and therefore may not be a juvenile from reproducing mussels in Lake Superior.

"There's no evidence of reproduction," Czypinski said.

Initial surveys of the four-year taskforce monitoring effort required the use of monitoring devices set near Madeline Island, in Chequamegon Bay, and close to shore from Sand River to Bad River - the equivalent distance of more than 100 km.

Plankton tows were also done to look for mussels in the Bay area.

Last year's zebra mussel survey depended on the efforts of divers who inspected the power plant and an Ashland coal dock.

This year Czypinski expects the divers to inspect the Ashland marina and the Ashland ore dock over a three-day stint sometime this summer.

Although divers are more expensive than monitoring devices, they're less labor intensive and a more effective way of looking for the exotics, Czypinski said.

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Zebra mussels...

Are native to Balkan region of Poland and the former Soviet Union.

Have striped shells, grow to about 50 mm long, and live from four to five years.

Crawl on lake bottoms with a foot and then usually attach to something hard or rocky.

Filter feed and primarily eat algae.

Can stay alive for several days out of water, depending on conditions.

Were likely introduced to the region through ocean freighter ballast water dumps in the Great Lakes and moved from place to place by attaching to boats and barges.

Are notorious for colonizing water supply pipes of hydroelectric and nuclear power plants, public water supply plants and industrial facilities. In the pipes, the mussels constrict flow and reduce intakes of mechanical systems.

Cause drag on boats they've attached to and can damage engine cooling systems.

Are known to have sunk buoys, fouled fishing gear, deteriorated dock pilings and corroded steel and concrete.

Adapted from U.S. Geological Survey

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Prevent the spread of zebra mussels

After boating remove visible vegetation from the boat, propeller, trailer and other equipment.

Flush the engine cooling system, live wells and bilge with hot water. Rinse other areas that may be wet.

Air dry the boat for five days before using it in uninfested waters.

Inspect the outside of the boat if docked in infested waters. If your gear or the boat feels gritty, young microscopic mussels may be attached.

Do not re-use bait and don't release live bait.

Adapted from Ohio Sea Grant

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