Province of Manitoba » Water Stewardship » Fish & Habitat » Aquatic Invasic Species
Zebra mussels have caused millions of dollars of damage in the Great Lakes region of Ontario and United States, and Europe. This damage includes:
- Plugging cooling water systems of boat motors by attaching to surfaces;
- Clogging water intakes of private cottages, towns, cities, and industries;
- Severely reducing recreation at beach areas due to the accumulation of sharp shells and foul odours from decaying, dead zebra mussels; and
- Reducing species of algae and microscopic aquatic animals that are important in the food chain.
ZEBRA MUSSELS IN PIPE |
ZEBRA MUSSELS ON BEACH |
No. Nor have zebra mussels been reported from any of the watershed that flows into Manitoba. They have been located in Lake Superior at Thunder Bay and Duluth, and in the Upper Mississippi River at St. Paul, Minnesota.
In June 1999, dead zebra mussels were found in Manitoba on the hull of a boat trailered from Orillia Ontario. The mussels were recognized by an alert marina worker who contacted the proper authorities. The boat was thoroughly cleaned before launching into the Red River. Although monitoring is carried out by the City of Winnipeg, Manitoba Hydro, and Manitoba Water Stewardship, no zebra mussels have been found in Manitoba waters. Legislation in the early 1990's makes it illegal to transport zebra mussels into Manitoba
The zebra mussel (Dreissena polymorpha) is a small animal that resembles freshwater clams. Zebra mussels grow up to five centimetres (two inches) in length and may live up to five years. Their name originated from the brown and white striped colour of its shell. One mature female zebra mussels can produce up to 40,000 eggs per year for a total of between 150,000 one million eggs during its life span depending on water quality conditions.
The eggs hatch into free-swimming microscopic larvae called veligers. During this stage, which lasts for approximately 8 to 33 days, the larvae remain suspended in the water. It is during this stage that the veligers can be transported undetected from lake to lake in bait buckets, live wells, and bilge water.
The distribution of zebra mussels is thought to be controlled mainly by temperature and calcium concentration in the water. They begin laying eggs when water temperatures rise to approximately 12ºC and continue until it cools below this temperature in the fall. Calcium is required for mussels to develop their hard shell.
A report by the Water Quality Management Section evaluated the risk of colonization of zebra mussels in numerous Manitoba lakes and rivers. Many southern prairie rivers are at high to moderate risk of successful zebra mussel colonization should they be introduced accidentally into these waters. Rivers and lakes in eastern Manitoba, for example in the Whiteshell Provincial Park, are at lower risk.
Tufts of hair-like filaments called byssal threads are used by the zebra mussel to adhere to solid surfaces. The threads form an extremely strong bond holding the mussels firmly in place.
Adult zebra mussels can survive out of water, in moist conditions, for up to two weeks. They attach to boats or other equipment being transported from one body of water to another and spread to new areas. Because of the large number of tourists, pleasure boaters and anglers moving between the infested waters of the Great Lakes, or the Upper Mississippi River systems and Manitoba, there is a high probability that zebra mussels could invade Manitoba lakes and streams.
Zebra Mussels on a stick
Zebra Mussel with byssal filaments
The spread of zebra mussels has been faster that expected in interconnected waters due in a large part to the movement of barges and ships The spread of zebra mussels across land to isolated water bodies has been slower than expected, however, the spread has been largely due to recreational watercraft.
Until recently, they were found only in Europe. Native to the Caspian, Black and Azov seas of eastern Europe, they were initially discovered in the Caspian Sea in 1769. Scientists first discovered a population of zebra mussels in Lake St. Clair in 1988. It is thought that zebra mussels were transported to North America in the ballast water of an ocean going vessel. This ballast water was then discharged in Lake St. Clair, Ontario, likely in early 1986.
Since zebra mussels were firstly introduced into Lake St. Clair, they are now found in all of the Great Lakes, the St Lawrence River to Quebec City, the Ottawa River, the Trent-Severn and Rideau Canal systems, the Hudson River and Erie Canal, the Mississippi River to the Gulf of Mexico, and most of the major tributaries of the Mississippi.
Zebra mussels could enter Manitoba through either the Red River system from the south or the Winnipeg and Rainy River systems from the east.
- They colonize surfaces that are not inhabited by other similar organisms and have few natural predators;
- They have an extremely successful reproductive strategy, producing many young zebra mussels that will survive even in poor environmental conditions;
- Thread-like filaments form a very strong bond between the zebra mussel and solid surfaces. This allows them to remain attached even in habitats with high water flows, such as water intakes and water lines;
- Zebra mussels can filter large quantities of water to remove food (mainly algae or plankton), and, therefore, can live in a variety of water bodies with a wide range of available food. It is estimated that one adult zebra mussel can filter all of the material out of one litre of water in one day.
Yes. Anti-fouling coatings and paints for boats and motors are commercially available that discourage zebra mussels and make equipment easier to clean. The control of zebra mussels in North America is aimed at reducing or eliminating them colonizing industrial infrastructure such as pipes, pumps, impellers, etc.
The best method of control is reducing the risk of accidental introduction. Once zebra mussels establish in Manitoba waters, they cannot be eradicated.
Before leaving infested waters, follow this five-point checklist:
- Drain all bilge water, live well, and bait buckets.
- Inspect all equipment.
- Scrape off ‘grainy’ surfaces (they could be young zebra mussels).
- Wash your boat with hot, soapy water.
- Dry equipment in the hot sun for three to five days, then scrape off remaining zebra mussels.
In addition to the five-point checklist, anyone transporting equipment from infested waters should take these precautions:
- Never transport live bait fish from infested waters to other bodies of water. Microscopic zebra mussel larvae may be easily transported with bait fish. It is illegal to transport live bait fish into Manitoba from other jurisdictions without a permit from Manitoba Water Stewardship.
- Avoid transferring zebra mussels to a new body of water. If equipment surfaces feel grainy or rough, young zebra mussels are likely attached. Clean any equipment that may have been in infested waters before transporting.
- Clean zebra mussels from equipment using the following methods:
- Scrape boat hulls with a paint scraper.
- Hot soapy water (about 80ºC used on boat hulls, motors, live wells, bait buckets and other equipment will kill zebra mussels almost immediately.
- High pressure water (at least 1,724 kilopascals or 250 pounds per square inch) or hot tap water forced through a strong garden hose, will kill most young zebra mussels on boat hulls and other equipment.
- Leave equipment in the hot sun for three to five days and most zebra mussels will die and drop off. Those remaining should be scraped off.
- Ensure areas around drain holes, speedometer brackets and other difficult to clean areas are thoroughly inspected and cleaned of zebra mussels.
- Dispose of removed zebra mussels and rinse solution well away from any water body.
Zebra mussels on lower unit of outboard motor
Although it takes time and effort to clean zebra mussels from boating and other equipment, it will save large sums of money for costly repairs and will give researchers an opportunity to find suitable control methods.
If you think you have located zebra mussels in Manitoba or need further information, please contact:
Manitoba Water Stewardship, Water Science and Management Branch
Water Quality Management Section
123 Main Street, Suite 160
Winnipeg, Manitoba, R3C 1A5
Telephone: 945-8146
Fax: 948-2357
Toll Free: 1-800-282-8069 (ext. 8146)
Photographs courtesy of US Sea Grant and Ontario Ministry of Natural Resources.