Zebra mussels in the Upper Mississippi

The news

Zebra mussels on clam: Zebra mussels grow on just about any hard surface, including the shells of native mussels, or this unlucky clam. The colonizing mussels make it impossible for the native mussels to breathe, eat, or reproduce. (Photo courtesy FWS)

The Minnesota DNR recently reported that zebra mussels (Dreissena polymorpha) have found their way into parts of the Upper Mississippi River. A boy discovered the invasive species while cleaning a minnow bucket that had been tied to the family's dock on Rice Lake in Brainerd, Minnesota. (Rice Lake is an impoundment of the Mississippi River.) The DNR says that the mussels have likely established themselves in other areas of the river, and the agency plans to step up public education efforts in an attempt to stop the further spread of the mussels.

What are these aquatic invaders?

Zebra mussels, an exotic species, were first found in the Great Lakes in 1986. Scientists suspect that zebra mussels were accidentally released there when ballast water contaminated with larvae was pumped out of ships arriving from Europe. (Water typically is pumped into the hold of a ship while it is in port to make it more stable for ocean travel.) Because they have few predators in North America, zebra mussels reproduce and spread rapidly. From the Great Lakes, zebras expanded quickly through the eastern and southern U.S.

What's the big deal?

Zebra mussels cause millions of dollars in damage annually by clogging power plant intake pipes, colonizing boat hauls, and coating virtually any hard surface in the water. Waves can pile dead zebra mussels up on beaches where the sharp shells inhibit recreational activity.

And zebra mussels seriously damage aquatic ecosystems. They kill native mussels by colonizing their shells so thickly that they are unable to eat, breathe, or reproduce, and zebra mussels consume much of the food that would otherwise be eaten by aquatic invertebrates, which form the foundation of many aquatic food chains.

What can be done?

Once well established, zebra mussels have proven impossible to get rid of. The best strategy is to prevent their spread in the first place by carefully inspecting boats, trailers, and fishing equipment being moved from one water body to another.

Your Comments, Thoughts, Questions, Ideas

Liza's picture
Liza says:

Here's a map showing zebra mussel distribution in the U.S. over time.

posted on Mon, 10/24/2005 - 4:12pm
Liza's picture
Liza says:

USGS has a zebra mussel page.

posted on Mon, 10/24/2005 - 4:16pm
Anonymous's picture
Anonymous says:

This site needs more information about the zebra mussel.\r\n

posted on Mon, 10/31/2005 - 3:29pm
Liza's picture
Liza says:

Like what? What would you like to see here? (Your comments are taken seriously, and if you can explain what you want, we'll try to post it.)

posted on Mon, 10/31/2005 - 3:42pm
Anonymous's picture
Anonymous says:

that picture looks pretty weird.

posted on Sun, 11/06/2005 - 1:27pm
Anonymous's picture
Anonymous says:

Zebra Mussels are different from our native mussels in that they don't need a host for their larval stage. The larvae is small- that's why it is so important to make sure your boat and gear are cleaned off when you are entering or exiting ANY body of water. WE are the reason the spread has been so great!

posted on Thu, 11/17/2005 - 9:36pm
crischan@drupal.org's picture

This is (just) another story of globalization. The kind of globalization which takes place since 1500. While I roam along local floodplains mapping two north american species (Acer negundo and Fraxinus pennsylvannica) mapping them for cutting next summer you in North America get our species...

Civilization exists by geological consent, subject to change without notice. -- Will Durant

posted on Mon, 12/19/2005 - 10:52am
Anonymous's picture
Anonymous says:

Hi -

Can you add photos to your site, showing what zebra mussel infestations look like (covering a dock, boat, motor intake, impact on recreation, etc.) I am trying to get our lake association membership educated about invasive species. Unfortunately, it is very difficult to get people motivated to do anything unless they see a very personal connection (i.e., something that would affect their (immediate) personal enjoyment or their pocketbook.) Most web sites show pictures of the zebra mussel for identification, but do not show pictures that help people understand how terrible it would be to get an infestation on our lake. Thank you if you can help!


posted on Tue, 08/01/2006 - 7:31pm
Megan's picture
Megan says:

Check out the Exotic Species Graphics Library on the Sea Grant Nonindigenous Species Site to see excellent pictures of the harm that zebra mussels can do. There are also great pictures of other invasive species (sea lamprey, Eurasian milfoil, and more).

posted on Tue, 08/01/2006 - 8:05pm
Anonymous's picture
Anonymous says:

Thanks for the tip! These were just what I was looking for!


posted on Wed, 08/02/2006 - 10:05pm

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