Research project in Outaouais to study the impacts of invasive aquatic plants


A small municipality in the Outaouais, with the help of the province of Quebec, is launching a study to study the impacts of an invasive aquatic plant that could damage the ecosystems of the region’s lakes.

Eurasian watermilfoil grows in dense strands just below the water’s surface.

The fast-growing perennial poses a threat to aquatic ecosystems due to its aggressive, relentless growth that can crowd out native plants and potentially harm fish communities.

Roch Carpentier, the mayor of Sainte-Thérèse-de-la-Gatineau, which borders the vast Thirty-One Mile Lake just south of Maniwaki, said the lake’s natural wealth benefits all the municipalities that surround it.

“We’re going to do everything we can to help the lake,” he said.

Roch Carpentier, mayor of Sainte-Thérèse-de-la-Gatineau, says he is hopeful that the Eurasian watermilfoil can be contained in order to keep the lake clean. (Christian Milette/Radio-Canada)

He said one of the lake’s main draws is its clean water, and overgrown vegetation could make boating difficult and keep tourists away.

The municipality is already considering laying burlap over the watermilfoil for the summer in an attempt to contain it.

“We can never make it go away,” Carpentier said in French, but he hopes it will be possible to reduce the spread of the plant.

Eurasian watermilfoil is so invasive in part because of how easily it spreads.

Even a small broken piece of the plant can spawn a whole new tangle of vegetation wherever it takes hold. This can happen when boats cut through plant mass and their spinning propellers scatter bits across a body of water.

Carpentier hopes that lake users will respect the signs that could be installed to keep boaters away from the milfoil.

Study to compare the health of fish populations

The municipality has given the green light to a study on the health of fish populations in areas affected by Eurasian watermilfoil.

“It’s an exotic and invasive species,” said Julie Deschênes, a biologist at Quebec’s Ministry of Forests, Wildlife and Parks, in French. “We would rather not have him.

“What we’re trying to see is if it’s still habitat for fish.”

Julie Deschênes, a biologist with the Quebec Ministry of Forests, Wildlife and Parks, says the new study will determine if Eurasian watermilfoil is harmful to the lake’s fish population. (Christian Milette/Radio-Canada)

The study will compare the fish population in areas invaded by the invasive plant and the number of locations inhabited by native aquatic plants.

To study the lake’s fish population, the team will use a combination of traditional nets and an electrofishing technique that briefly stuns fish, allowing researchers to collect fish, identify, count and measure them, then release them into the water.

The Thirty-One Mile Lake Study will use a variety of fishing techniques to study the health of the fish population. (Christian Milette/Radio-Canada)

Non-native plant now widespread in several regions

Eurasian watermilfoil is not native to Canada — it was introduced to North America in the 19th century – but he’s been here for decades.

The plant was first spotted in Canada in Lake Erie in 1961.

In the decades that followed, it spread to all of the Great Lakes, the St. Lawrence River, and many smaller lakes in Ontario and eastern Quebec. It is one of the most common invasive aquatic plants in Ontario.

In 2015 it was identified in New Brunswickwhere it also spread rapidly.

A researcher measures a fish taken from Thirty-One Mile Lake. The study aims to determine if Eurasian watermilfoil is detrimental to the health of the lake’s fish population. (Christian Milette/Radio-Canada)

Hope for future tourism

Marlène Thonnar, president of a society that hopes to make Thirty-One Mile Lake a provincial park, said she hopes the study results will help educate visitors to the lake on how to help preserve the ecosystem health.

“If we have a lot of scientific information… to do [visitors] understanding what they need to do and what they can’t do to preserve the wonderful lake we have is positive,” she said.

Marlène Thonnar hopes the results of the study will help educate visitors to the lake on how to help maintain the health of the ecosystem, and adds that time is running out. (Christian Milette/Radio-Canada)

She added that time is running out because Eurasian watermilfoil is spreading rapidly in the lake.

“We really have to be quick…on this exercise [to raise public awareness]“, said Thonnar.

The Thirty-One Mile Lake study takes place from July to the end of November.


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