Beneath The Surface: Mussels on the Move

Why preventing a zebra mussel invasion benefits you

A zebra mussel

A zebra mussel

The province of Manitoba recently introduced legislation mandating that boaters remove aquatic vegetation from their boats before leaving a lake. Aquatic vegetation can carry zebra mussels, and if the law passes, transporting, possessing or releasing zebra mussels will be illegal. So far, B.C. is in the clear, but there have been several close calls. Just one month ago, a boat en route from Michigan to Alaska was intercepted in neighbouring Alberta after a zebra mussel infestation was detected.

What is a Zebra Mussel?

The zebra mussel (Dreissena polymorpha) is a small bivalve and an invasive aquatic species to North America. It is native to the Caspian and Black Sea Region and was introduced unwittingly through the ballast water of a transatlantic freighter ship in the mid-1980s. With no known predators to keep populations under control in the U.S. and Canada, zebra mussels have spread rapidly across the Great Lakes region, where they have wreaked serious havoc to biodiversity, fisheries and water supply systems.

Food-web game changers

Zebra mussels are efficient filter-feeders, filtering small organisms and organic particles out of the water at a very high rate. This reduces the amount of food available for native fish, such as salmon and trout, as well as a vast variety of other organisms that are dependent on phyto- and zoo-plankton. These mussels also alter the natural balance of algae, leading to a higher concentration of blue-green algae. The Invasive Species Council of British Columbia warns that “high levels of blue-green algae can become toxic to aquatic life, can cause taste and odour problems in drinking water supplies, and can be very unpleasant for recreational users.”

Resilient hitchhikers

Once zebra mussels attach themselves to an ideal habitat, they multiply rapidly, colonizing hard surfaces and water equipment such as boats, engines, and hulls. The protection and constant flow of water provided by drinking water intake pipes attract zebra mussels, requiring costly measures to control clogging (see picture below). Boats or equipment transported from one water body to another serve as an easy route for zebra mussels to spread almost without hindrance. Their D-shaped shell is also razor sharp. As someone who loves to swim in the lake, I (on behalf of feet everywhere) say no, thank you.

Preventing invasive mussels from entering our lakes is imperative to ensure that the Headwaters of the Columbia River remain drinkable, fishable and swimmable. Executive Director for Central Kootenay Invasive Plant Committee Crystal Klym urged that “an ounce of prevention is worth a pound of cure. By preventing these species from entering our lakes and rivers, we can save millions of dollars in impacts in the future.” The Okanagan Basin Water Board estimates an invasion would cost more than $40 million in the Okanagan alone.

See Part 2 of “Mussels on the Move” in next month’s Beneath The Surface column for information on what’s being done in the region and how you can help stop the spread of zebra and quagga mussels into our lakes and rivers.

Beneath The Surface is based on the principle that there is often more to know than what is visible from the “surface” of an issue. If there is something that concerns you about the lake and you want to get to the “bottom of it”, call Lake Windermere Ambassadors program co-ordinator Megan Peloso at 250-341-6898  or email and inspire the next column!