Ten things you should know about zebra mussels:
1. Where did Zebra Mussels come from?
When large ships head out on to the open ocean, they need to carry weight, called ballast, to remain stable. If the ship is not transporting cargo, that ballast is water. This water is picked up in the homeport carried with in the ship and dumped out as they prepare to load cargo. So whatever is in the ballast can travel thousands of miles before being released into new waters.
Zebra mussels were first discovered in Detroit's Lake St. Clair in 1988. They would have been brought there in ballast water, survived, and reproduced to a number where they were noticed. Since then they have spread by attaching to boats and floating with currents throughout the Great Lakes and Mississippi watersheds. This is where they are found today as well as some scattered lakes.
2. Why do they like to stick to hard things like bridges and boats?
3. How do they attach to things?
4. What do they eat?
5. Is there anything in their shell?
6. How do they travel from place to place?
7. Are they harmful to humans?
8. Are they harmful to plants and animals?
As for animals, if they enjoy increases in water clarity and plant cover-they may do ok. But animals that compete with zebra mussels, like our rich assortment of native mussels, will find it tough going. Zebra mussels can take much of food away from other animals. They reduce the oxygen in the water by critical amounts, and they colonize areas on the river bottom so nothing else can move in. In addition, zebra mussels attach themselves to native mussel so the natives can't eat, breathe or reproduce. In other areas of the country, native mussels have been wiped out entirely-we don't want this to happen here on the St. Croix. It's always easier to prevent an invasion than to mop up afterwards. Please help us by making sure your boat or bait bucket is free of exotic species.
9. When did they arrive at the St. Croix and what is the National Park Service doing?
Armed with the unfortunate knowledge that zebra mussels have arrived, the National Park Service has begun the task of evaluating every aspect of its prevention and control plan. Rules designed to stop the spread of zebra mussels from infested to noninfested waters will be strictly enforced. The river may indeed be at a juncture in its ecological history--what actions are taken in the future may be critical to the plants and animals that call the river home. Of additional importance is considering a recreating public that enjoys the many wonderful aspects of this nationally protected waterway. The management issues surrounding zebra mussels are complex and may be controversial, but are important for the well being of the St. Croix National Scenic Riverway for decades to come.
10. Where else can I get information about Zebra Mussels?
http://www.seagrant.umn.edu/ais/zebramussels_threaten This site also provides information on other exotic species like rusty crayfish and sea lampreys.
Zebra Mussel Activities Reports:
A multiagency task force has been assembled to respond to the threat zebra mussels pose to the St. Croix River. Members meet annually to review and update a response plan based on current conditions. Presented are the annual spring action plans:
In 2005 and 2006, the task force provided their aquatic invasive species activities to the U.S. Fish and Wildlife Service:
Last updated: April 30, 2019