Discovery of zebra mussel near Mactaquac raises alarm over spread of invasive species

The recent discovery of a live zebra mussel near Mactaquac, west of Fredericton, is causing concern about the spread of this invasive species in New Brunswick. With potential impacts on ecosystems, infrastructure, boats, and beaches, the Department of Fisheries and Oceans found an adult zebra mussel on a dock in the St. John River just north of the Mactaquac Dam in December.

Terry Melanson, team lead for the department’s aquatic invasive species program, noted that while the single mussel doesn’t confirm the species has taken hold in that part of the river, it does suggest that the mollusk has spread from the Edmundston region, where it was initially discovered in 2023. The extent to which zebra mussels will establish themselves in the St. John River remains uncertain.

Zebra mussels, native to eastern European waters, entered the Great Lakes in the late 1980s through ballast water discharged from ships. Since then, they have spread through much of eastern Canada and the United States. The threat to New Brunswick first arose in 2022 when zebra mussels were detected in Quebec’s Lake Temiscouata, which drains into the Madawaska River, a tributary of the St. John River. Subsequently, the mussels were found in the Madawaska River, including on infrastructure connected to Edmundston’s Madawaska Dam.

Last summer, samples collected by the Department of Fisheries and Oceans found zebra mussel larvae in various locations in the St. John River as far south as the Mactaquac Dam. Melanson highlighted the potential risk zebra mussels pose to the yellow lampmussel, a species of “special concern” according to the Committee on the Status of Endangered Wildlife in Canada, as they compete for the same resources.

In addition to threatening native species, zebra mussels can cause damage to infrastructure and pose risks to humans. They can clog municipal intake and drainage pipes along the St. John River, as well as infrastructure for hydroelectric dams. Swimming spots could also become hazardous if zebra mussels spread and multiply in the river due to their sharp shells.

Sarah Cusack, a project co-ordinator with the New Brunswick Invasive Species Council, emphasized the importance of preventing the spread of zebra mussels. Recreational boaters are advised to thoroughly clean their boats, drain captured water, and let them dry out before putting them back in the water to prevent unintentional transportation of zebra mussel larvae.

The introduction of zebra mussels to North America has resulted in billions of dollars in damages and management requirements elsewhere. Cusack stressed that this threat should be taken seriously to prevent potential changes in freshwater ecosystems and the cascading effects that could occur due to the rapid spread of zebra mussels.