Zebra mussels are typically found in infested lakes and rivers attached to hard surfaces including rocks, other mussels, plant stems, docks, boats, and pipes. In Vermont, they have become established in Lake Champlain and Lake Bomoseen.
Zebra mussels (Dreissena polymorpha) get their name from the striped pattern on their shells. Shells are usually yellowish brown but can vary from light to dark with many or few stripes. Zebra mussels are D-shaped and generally do not exceed 2 inches in length. They attach to objects using strong, sticky threads called byssal threads.
Zebra mussels have many ecological and economic impacts in waters they have invaded. They reproduce quickly, form dense colonies, and can completely coat lake bottoms in densities of more than 10,000 per square meter.
Zebra mussels are efficient filter feeders. One mussel can filter one liter of water per day, siphoning vast amounts of microscopic plants known as phytoplankton from the water. This reduces available food resources for native species that rely on plankton and can impact native mussel populations in particular, which have greatly declined since the introduction of zebra mussels. Zebra mussels also impact native mussel species by attaching to the outside of their shells, suffocating them.
Dense colonies of zebra mussels can also clog outboard boat motors and water intake pipes of power plants, water treatment plants, and irrigation systems. This has resulted in hundreds of millions of dollars in repairs since their introduction to the US in the 1980s.
Zebra mussel shells are extremely sharp and break easily when stepped on, which can cause injury to people walking or swimming in infested waters.
Control and Prevention
Colonies in intake pipes have been treated chemically and thermally, however once established, populations are almost impossible to eradicate. The best management option is spread prevention.
Zebra mussels are usually spread unintentionally on boats, trailers, and other vessels as well as equipment used in the water. Zebra mussel larvae are microscopic and float in the water column. This makes them easy to accidentally transport in livewells or bait buckets and other areas that contain water or stay damp. Suspended larvae can also spread by water currents.
Adult zebra mussels can be spread when attached to boat hulls or plant fragments caught on boat trailers. When vessels and equipment are transported to another waterbody without proper cleaning, zebra mussels can be spread and introduced to the new lake or river.
The most effective way to prevent the spread of zebra mussels is to practice Clean, Drain, Dry spread prevention methods. Drain all water from your boat, canoe, kayak, and other vessels and any equipment used in the water. Clean off any mud and plant fragments and dispose of properly. Dry all damp areas of boats and vessels, such as livewells and bilges, with a towel and let air dry in the sun for at least five days before using in another waterbody. If this is not possible, rinse equipment with hot, high-pressure water.
For more on spread prevention
VT Department of Environmental Conservation
For volunteer opportunities to help monitor and protect Vermont's waters
Minnesota Department of Natural Resources