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Duluth conference looks at invasive species from land and water

DULUTH - The warning goes "one if by land, two if by sea," but what happens when the invaders are coming from both?

Paul Revere and friends might be a little confused in 2008 with an attack by foreign invaders crossing oceans to get to the Northland, crawling and swimming into our ecosystems.

The crawlers and swimmers, along with flying and leaping invading species, will be the topic of what's slated to be the first annual Minnesota Invasive Species Conference, which began Sunday and runs through Tuesday at the Duluth Entertainment Convention Center.

More than 360 people were slated to attend. The event follows last year's Lake Superior conference in Duluth that focused exclusively on the big lake's problems.

"We've focused a lot on the aquatic invasive species before, but we've never brought [discussions of] all invasive species together before,'' said Marie Zhuikov, spokesperson for Minnesota Sea Grant, a co-sponsor of the event.

Presenters will share the latest scientific findings about invasive species along with the efforts to keep them from spreading. Forums include discussions on ship designs for ballast water as well as educational campaigns to stop people from dumping pet shop species into their local ponds.

There's good and bad news. Educational efforts continue to slow the spread of species like zebra mussels to inland lakes, with anglers and boaters taking precautions to prevent moving the critters.

But other species, like ash borers, continue to move closer to the state, spread as infested firewood or nursery stock is moved north.

On land, exotic earth worms are damaging maple forests, emerald ash borers from China are killing ash trees in Wisconsin, gypsy moths may have taken hold on the North Shore, and exotic knapweed, garlic mustard and buckthorn are overtaking Northland fields and forests.

The water invaders are perhaps better known, at least around Lake Superior, where zebra mussels, ruffe, and spiny water fleas have become well known in their adopted home. Jumping Asian carp are moving up the Mississippi River.

The list goes on. Estimated damage and control cost of invasive species in the U.S. alone amount to more than $138 billion annually, according to a study published in Ecological Economics. (Cornell University puts the cost of foreign, noxious weeds alone at $27 billion per year.)

In recent weeks, Minnesota officials found barges from Wisconsin -- trucked into the state for work on a new St. Cloud bridge over the Mississippi River -- covered in zebra mussels. The discovery was made just before the barges were used.

"The number of new species coming in isn't slowing at all,'' said Jay Rendall, invasive species prevention coordinator for the Minnesota Department of Natural Resources and a presenter at the conference.

Skeptics might suggest throwing up our hands and allowing this global ecological blender to continue mixing species never intended to see each other as an ultimate survival of the fittest. But Rendall said there's too much at stake.

"If we just opened the gates, there's so much more out there that could show up,'' he said. "We've only seen the tip of the iceberg.''