Fight is on to stop spread of invasive zebra mussels in St. John River

Clarissa Hoffman and Kristen Elton of the New Brunswick Invasive Species Council aren't about to let something smaller than a pistachioruin a treasured ecosystem.

They're working to stop the spread of the prolific zebra mussel in the watershed of the St. John River, also known as Wolastoq.

Zebra mussels were first detected in New Brunswick in the summer of 2023, ayear after they were found in Quebec's Lac Tmiscouata.

Elton, program director for the council, said zebra mussels are considered "ecosystem engineers."

"Not only are they taking food and resources out of the water, they're actually changing the physical characteristics and the biochemistry," she said.

"So when they're filtering everything out of the water, they're sometimes clarifying that water as well, which some people think can be a good thing, but they're actually taking everything out."

Clearer water means sunlight can penetrate deeper, which changes the plant composition and warms the water, leading to more favourable conditions for algae growth and cyanobacteria, which can be toxic.

WATCH | Testing has turned up zebra mussel larvae as far south as Mactaquac Headpond:

Stopping the spread of zebra mussels

4 months ago

Duration 2:58

New Brunswicks Invasive Species Council takes steps to slow attack on St. John River.

Environmental DNA testing by the not-for-profit has turned up positive results for zebra mussel larvae as far south as Mactaquac.

"And so it's only really a matter of time before the adults are found," said Elton. "We got positive results down in Grand Falls, Nackawic and then in the head pond just above Mactaquac as well."

Boat washing, draining critical for prevention

The council is moving quickly to prevent the spread and mitigate the damage. This summer it is collaborating with five organizations in Quebec and New Brunswick.

Hoffman, a project co-ordinator with the council, says permanent boat washing stations have been set up at Lac Baker, Mount Carleton Park and Parc de Republique, with a few more in the works.

Travelling mobile boat washes will be in place as well, and will focus on events such as fishing tournaments where people may come from farther away.

"There's a lot of travel of boaters and anglers recreationists between P.E.I. and New Brunswick and Nova Scotia. So it is a big concern that it will spread from here and just go east," Hoffman said.

The boat washes are part of the "Clean, Drain, Dry campaign," she said, which is meant to stop the zebra mussels from hitching a ride to a new body of water.

"It's all about prevention," Hoffmansaid.

"Now they're in the Wolostoq-St. John, there's really no chance that they'll be removed from this water body. So we're really trying to emphasize to people to make sure they're cleaning their boats so it's not moved to other water bodies in New Brunswick."

Prolific species, negative effects

Zebra mussels are tiny but can grow in dense clusters ofup to 700,000 per square metre, according to Hoffman.

They have no predators, and besides harming the ecosystemthey also can "clog up infrastructure."

"They'll cover pipes, they'll block motors, cover boats, really anything that's in the water will get coated in them," said Hoffman.

In addition, the mussels are very sharp and can cut swimmers and boaters, taking away from their enjoyment of lakes and rivers.

Hoffman and Elton urgeanyone using New Brunswick waterways to do their part this summer to prevent the spread of the invasive species.

Cleaning and draining the water from anythingused in rivers or lakes will help, Elton said,including aquatic equipment such as boat trailers, bait boxes, ballastsand even floaties.

"Make sure that you're cleaning, draining and drying that before you put it into a new water body," she said. "The idea being that you're going to help limit as much as possible the chance of an aquatic hitchhiker from hopping water bodies with you.

"The drying is really important because zebra mussels have been shown to live up to 30 days out of water in the right conditions."

Hoffman hopes the diligence of New Brunswickers will pay off, and give the province the best chance at preservingits freshwater bodies.