Zebra mussels have taken over Rideau River, study finds

A new 26-year study of zebra mussels in the Rideau River clearly shows the tiny invaders have swept through the river and are here to stay.

Researchers with the Canadian Museum of Nature first started surveying the zebra mussel population after the species wasfound in Mooney's Bay in 1990.

In an article published in the Canadian Journal of Zoology on Wednesday, they showhow the mussels have effectively taken over the Rideau River.

"The Rideau has what it takes to have them explode in numbers," said Dr. Andre Martel, the study's lead author, on CBC Radio's All In A Day.

"If you go diving, scuba diving in Mooney's Bay, or snorkeling and you just check the bottom, everything is covered by zebras."

Introduced in 1980s

Zebra mussels came to North America on commercial vessels in the mid-1980sand have since spread through lakes and rivers.

Martel said the nutrients in the Rideau River have madeit ideal for the mussels.By 1995, the study's researchers had found they were so prevalent that there could be as many as 300,000 of them in a square metre.

They were especially concentrated in the stretch of the river between Manotick and Ottawa, including in the Rideau Canal.

The researchers sampled the same areas in the river system each year,including regions in the canal that had been drained, to see where the mussels were accumulating.

Martel said they found them growingon top of existing species, many of which they largelywiped out.

"The impact has been severe on our native mussels," he said. "We do have to pay a price when we introduce such an invasive species."

Martel said there are a few isolated spots in the river where native mussels have survived, and the researcherswant to perform furtherstudies to see what'sallowed that to happen.

Full river impacted

Initially, the upstream area of the river from Manotick to Smiths Falls, Ont., wasn't as inundated, Martel said, but thathas changed.

"For awhile, we thought our native species would be spared. Unfortunately, this was not so. We had beautiful populations of native mussels and unfortunately we have lost [them]" he said.

Martel toldAll In A Daythat peopleshouldmake sure their boats are clean when they take them out of the waterto prevent the population from expandingfurther.

"We spread the beast," he said. "We spread the zebras around."