Chances are if you've been diving, swimming, fishing or boating in the lakes or rivers of Minnesota you've encountered a Zebra Mussel.
Zebra mussels are an invasive species infiltrating lakes and rivers around the United States. Native to Eastern Europe and Western Russia, the zebra mussel was first discovered in the Great Lakes in 1988, probably transported here in the ballast of a ship. They quickly spread from the Great Lakes to other bodies of water via river currents, or by attaching to boats and other items. Within a year, the first one was discovered in Minnesota. Today they are present in 25 states and at least 65 Minnesota Lakes.
Zebra mussels are fresh water bivalves that resemble clams. They are d-shaped with yellow and brown stripes and are usually between .25” and 2” long. They reproduce between spring and fall and it is estimated that a female mussel can produce between 100,000 to 1 million eggs a year. The eggs transform into larvae called veligers that begin to form shells, within 2-3 weeks these veligers start attaching to objects by way of a byssal thread (a strong filament they secrete). A zebra mussel can live up to 5 years in water, and in the right conditions, several days outside of water.
The trouble with Zebra Mussels
While some may argue that the presence of zebra mussels is a positive thing because of increased visibility in the water they inhabit, the damage they cause far outweighs that benefit.
Zebra mussels have a negative impact on the ecosystems they inhabit. They attach to bottom dwelling organisms, including native mussels, which die when covered excessively. They filter plankton from the water, reducing the available food needed by local fish larvae. This filtration also increases the clarity of the water, which allows the sun to reach greater depths, allowing aquatic plants to grow deeper and thicker. The end result is a lake uninhabitable to local fish species.
Divers may appreciate the increased visibility until they reach their shipwreck or dive stand, only to discover it is covered and damaged by zebra mussels.
Sport fishermen lose time and money replacing their fishing lines cut by the sharp shells of the zebra mussel.
With shells sharp enough to cut through fishing lines; imagine the injuries caused to swimmers, boaters, children or anyone cooling off in the water that accidentally steps on one. Cities are now spending money and time to remove this threat.
Water treatment and power plants constantly need to treat their systems to keep them clean of zebra mussels. The cost to keep their facilities clean is inevitably passed down to the consumer.
Boaters, with boats moored or transported, are faced with extra maintenance and costs to ensure their boats do not house or transport the organisms.
These are just some of the many issues caused by the zebra mussels
Ways to stop the spread of Zebra Mussels
Currently, there is no way to control zebra mussels. The only option is to keep them contained and stop them from spreading to other bodies of water. They are spread by boats, docks, aquatic plants, bait buckets, nets, bilges or any water moved from an infested lake or river.
If you dive or boat in an infested body of water, here are ways to make sure you don’t spread zebra mussels:
- Check the DNR’s website to see if the body of water you are entering is infested or clean.
- Learn to identify zebra mussels so that new appearances can be reported: 651-259-5100
- If you find zebra mussels underwater, do not bring the item to the surface to discard of or transport. Not only does it increase the possibility of spreading, it is illegal.
- Empty any water that may be in your BCD or other gear.
- Drain all water from boat bilges, motors, live wells, bait containers, or any other equipment.
- Dispose of unused live bait in trash.
- Thoroughly clean all dive gear and let dry for five days before using it in another body of water.
- Examine boat hulls, swim platforms, swim ladders or any item that has been in the water.
- Rinse boat and equipment with high pressure and/or hot water
As divers, we have a unique view of lakes. If you’d like to utilize this view and help the DNR , please visit the DNR website and volunteer to become a zebra mussel monitor.