Associated Press:
http://www.ohio.com/news/ap?articleID=2862722&c=y
Invasive mussels may have reached Isle Royale
By JOHN FLESHER AP Environmental Writer
Published on Monday Sep 21, 2009
Debug
Foreign mussels may have found their way to Isle Royale National Park in Lake Superior, a potential threat to native species on the remote island chain, an official said Monday.
Divers found a small colony of perhaps two dozen suspicious mussels last week in Washington Harbor on the west side of the 45-mile-long park, Superintendent Phyllis Green said. A single mussel was found on the east side.
Staffers believe they are either zebra mussels or their relatives, quagga mussels. Both are invasive species that originated in the Black and Caspian seas in Eastern Europe and hitched rides to the Great Lakes in ballast tanks of oceangoing freighters in the 1980s.
Since their arrival, they have spread widely in the Great Lakes, causing millions of dollars in damage by clogging water intake pipes and disrupting the food web. They're also considered a likely suspect in die-offs of loons, gulls and other waterfowl.
Isle Royale's inland lakes are home to some of the Great Lakes region's largest surviving populations of native mussels, Green said. In other places, zebra and quagga mussels have displaced natives by out-competing them for food.
"This is a very sad development," said Jennifer Nalbone, invasive species director for Great Lakes United, a U.S.-Canadian group that supports tougher regulation of ship ballast. "Isle Royale is a very precious and unique part of the Great Lakes."
It's unclear how the mussels got to the park, Green said.
Two years ago, she issued an order prohibiting boaters or commercial shippers from emptying ballast tanks near Isle Royale. It was designed primarily to prevent viral hemorrhagic septicemia, a fish-killing virus, from invading the park's waters.
Zebra mussels are known to exist in a handful of Lake Superior harbors, including Duluth, Minn., about 150 miles southeast of Isle Royale. Yet the lake's depth and cold temperatures have prevented the kind of heavy infestations found elsewhere in the Great Lakes.
That the mussels might have turned up at Isle Royale demonstrates that "once an invasive species is here, it's incredibly hard to control," Nalbone said.
Staffers are continuing to inspect the park for other signs of foreign mussels and discussing possible containment or eradication strategies if an invasion is under way, Green said.
Treating the waters with biocides is one option, she said. Crews also are inspecting hulls of the park's boats.
Isle Royale is a federal wilderness area and protecting its native species is a top priority, Green said.
"The park has removed all visible specimens and will be stepping up monitoring for next year," she said.
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On the Net: Isle Royale National Park:
http://www.nps.gov/isro/index.htm
>>>
Duluth News Tribune:
http://www.duluthnewstribune.com/event/article/id/147148/
Zebra mussels make it to Isle Royale
Zebra mussels have invaded Isle Royale National Park, with Park Service officials Monday confirming the finding for the first time.
By: John Myers, Duluth News Tribune
Zebra mussels have invaded Isle Royale National Park, with Park Service officials Monday confirming the finding for the first time.
Park officials are concerned because Isle Royale holds one of the region’s largest remaining populations of native mussels on small lakes on the island. Zebra mussels have in many cases wiped out native mussel populations across the Great Lakes.
“A lot of the boats that come here come from harbors that have zebra mussel problems on other parts of [Lake Superior],” Isle Royale superintendent Phyllis Green said. “But we may never know exactly how they got here.”
Green said her staff will do more than try to prevent the spread of mussels to inland waters. Green is calling for an all-out effort to eradicate the existing colony from the park’s Lake Superior waters.
A colony of mussels was found at the west end of the island in Washington Harbor last week. A single zebra mussel also was found at the east end of the island.
Park Service officials say they believe the mussels are the smaller zebra mussels and not their larger cousin, the Quagga mussel, which is considered more menacing because it can reproduce in deeper, colder waters.
Isle Royale, Lake Superior’s largest island, sits about 15 miles from Grand Portage off Minnesota’s North Shore.
The finding comes 20 years after zebra mussels first were confirmed in Lake Superior in the Duluth-Superior harbor. Though the mussels can’t move far on their own, they often are spread by boaters and anglers when the thumbnail-size critters hitchhike in bait buckets and on other gear or even in engine cooling lines and attached to hulls.
They also can hitchhike in the ballast water of larger ships, although ballasted ships aren’t common in waters adjacent to Isle Royale.
Green said divers already have pulled 24 mussels off the Windigo dock. They haven’t found any more but are continuing to search, she said.
Green said crews will continue to take water samples to check for zebra mussel larvae called veligers. She said it’s unclear if the mussels were mature enough to reproduce. It’s possible the Park Service could poison water near the dock to kill additional larvae.
Green made headlines in 2007 when she began treating ballast water in the park’s Ranger III ferry boat that brings passengers and supplies to the island from the mainland — the first boat to regularly treat ballast on the Great Lakes. So far, tests show the treatment has been working to kill any living organisms in the ballast tanks.
Doug Jensen, aquatic invasive species expert for Minnesota Sea Grant, said efforts to eliminate established populations of zebra mussels have generally been successful only in controlled areas, such as flooded mine pits. One eradication effort at New York’s Lake George may show signs of success, he said.
“There haven’t been many cases of actually eradicating an established population in a natural lake,’’ Jensen said. “They’d have to be very localized to have any success. But maybe they caught it early enough.’’
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