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

Zebra mussels, shown here on the left, have a lifespan of 2-5 years, with a single female zebra mussel laying up to a million larvae a year. They compete with native mussels, show here on the right, for food and will attach themselves to native mussels to suffocate them. (Shane Fowler/CBC - image credit)
Zebra mussels, shown here on the left, have a lifespan of 2-5 years, with a single female zebra mussel laying up to a million larvae a year. They compete with native mussels, show here on the right, for food and will attach themselves to native mussels to suffocate them. (Shane Fowler/CBC - image credit)

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

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

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

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:

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."

The project coordinator for on the ground projects for the New Brunswick Invasive Species Council (NBISC) Clarissa Hoffman says evidence of zebra mussels have been found as far south as Fredericton in the Wolastoq (St. John River).
The project coordinator for on the ground projects for the New Brunswick Invasive Species Council (NBISC) Clarissa Hoffman says evidence of zebra mussels have been found as far south as Fredericton in the Wolastoq (St. John River).

Clarissa Hoffman, co-ordinator for on-the-ground projects with the New Brunswick Invasive Species Council, says evidence of zebra mussels has been found in the Saint John River as far south as Fredericton. (Shane Fowler/CBC)

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," Hoffman said.

"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."

Clarissa Hoffman checks a lake for zebra mussels with an environmental DNA testing  and says other tests used to control the spread in high priority water bodies in New Brunswick include visual surveys and settlement plates
Clarissa Hoffman checks a lake for zebra mussels with an environmental DNA testing and says other tests used to control the spread in high priority water bodies in New Brunswick include visual surveys and settlement plates

Hoffman checks a lake for zebra mussels by using environmental DNA testing. (Summitted by Clarissa Hoffman)

Prolific species, negative effects

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

They have no predators, and besides harming the ecosystem they 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 urge anyone using New Brunswick waterways to do their part this summer to prevent the spread of the invasive species.

OZERO solutions' Maxime Guay participates in Clean, Drain, Dry; an ongoing public awareness campaign used to take care to clean boats and other watercraft before they are moved between bodies of water in order to present the spread of invasive species. OZERO solutions is a company who makes boat wash stations.
OZERO solutions' Maxime Guay participates in Clean, Drain, Dry; an ongoing public awareness campaign used to take care to clean boats and other watercraft before they are moved between bodies of water in order to present the spread of invasive species. OZERO solutions is a company who makes boat wash stations.

The NBISC has launched a 'Clean, Drain, Dry' public awareness campaign to help fight the spread of invasive species between bodies of water. (Submitted by Clarissa Hoffman)

Cleaning and draining the water from anything used in rivers or lakes will help, Elton said, including aquatic equipment such as boat trailers, bait boxes, ballasts and 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 preserving its freshwater bodies.