Zebra Mussels

On October 3, 2003 the discovery in Lake Ossawinnamakee of zebra mussels, an exotic species, was confirmed. DNR officials are not sure how they gotthere or from which source they came, the Lower Mississippi River, Lake Superior, or Zumbro Lake in southeastern Minnesota (the only known places of infestation in Minnesota).
Lake Ossawinnamakee is only the second inland water to become infested. The DNR is developing a plan of what to do, but there is no miracle cure for zebra mussels and virtually no way of exterminating them.
The DNR is now also concerned about Pelican Brook, the Pine River, and the Upper Mississippi River because the microscopic veliger stage of the zebra mussel easily drifts downstream and will attach to any solid object. There is also possible concern for Pelican Lake.

The above paragraphs were written in 2003. For the rest of the story, read the following article by Vince Meyer of the Brainerd Dispatch.

Major environmental story unfolds in Brainerd lakes area

OUTDOORS Printed in the Brainerd Dispatch on October 28, 2005
By VINCE MEYER Outdoors Editor
The recent discovery of zebra mussels in Rice Lake, a 400-acre impoundment on the Mississippi River, is serious business.
The river is the most important body of water in North America, Great Lakes notwithstanding. Its importance to fish, wildlife and human commerce cannot be understated. The detrimental effects zebra mussels might have on this already over-burdened and fragile ecosystem could be significant.
The river has absorbed a lot over the past 100 years. Can it handle an invasion by zebra mussels?

If you're new to the topic, zebra mussels are native to the Caspian Sea. They first were found in America in Michigan's Lake St. Clair in 1988 and probably got here in the ballast of a cargo ship. Already present in the river below the Twin Cities, they're now present above and could colonize suitable habitat from Brainerd downstream.
Zebra mussels haven't been around long enough to seriously damage the waters in which they exist, but grim scenarios are several, including:

* Zebra mussels eliminate native mussels. Replacing a native species with an exotic is never good.

* Zebra mussels clog the water systems of power plants, water treatment plants and irrigation systems. The amount of money spent on damage control could be staggering.

* Zebra mussels filter plankton from water, possibly eliminating the food young fish need to grow. Imagine if the Mississippi River's sport fishery crashed.

* Zebra mussels' shells are sharp. Nobody would want to swim in a lake in which the bottom is covered with zebra mussel shells.

If mussels establish populations in the river downstream to the Twin Cities more boaters will be exposed to infested waters. This could speed the overland movement to inland lakes if those boaters fail to remove weeds from their boats and trailers and drain all water before leaving a river access.

"Very little can be done to prevent the downstream drift of veligers (young mussels)," said Tim Brastrup, DNR area fisheries manager in Brainerd. "Natural mortality kills many, and areas of the river with turbulence and swift current can prevent settling and might even kill some of them.

"In the Mississippi below St. Paul the mussels have established populations in Lake Pepin and other places with low current. The dams in the river down there have not prevented their spreading. They certainly have the potential to colonize similar habitats in the river downstream from Brainerd."

That would be a problem, for there are three paper mills, three power plants and several cities that get their municipal water supply from the river. The expense for control and cleaning could be incredible.

Much of the above is speculation, but it's certain that chemical control isn't the answer and would obviously be impractical in the Mississippi River. A lot of time and money went into copper sulfate treatments in Lake Ossawinnamakee the past two years, but all that work might have been for naught. The zebra mussels that got into Rice Lake might have come from Ossawinnamakee before anybody knew the lake had the mussels. Though they haven't been found in Pelican Brook nor the Pine River, their connections to the Mississippi might have been how they got down to Rice Lake.

This week the DNR searched for zebra mussels in the pool below the Brainerd dam and in the river upstream from Rice Lake. As of Wednesday none were found.

Brastrup said the DNR was considering placing a barrier or another physical control that would create extreme turbulence in Pelican Brook to prevent veligers from moving downstream. Now, with the mussels reproducing in a lake downstream of those waters, it's too late and the plan is on hold.

Zebra mussels are in the Mississippi River to stay. Where the fate of the river flows from here is anybody's guess.

VINCE MEYER, outdoors editor, can be reached at vince.meyer@brainerddispatch.com or 855-5862.