Last week was Invasive Species Awareness Week in Canada.
This is a collaborative campaign focused on raising awareness of invasive species and how to protect Canada’s natural spaces.
But why should we care about invasive species in Ontario? And what are some of the tangible impacts they have? To answer these questions, several experts in the field shared their knowledge and concerns about three key invasive species that pose a significant threat to our native species and biodiversity.
If you’ve ever gone fishing in Lake Superior or Lake Huron and caught a lake trout, chances are the fish has a circular scar on it.
These scars are made by the sea lamprey, perhaps the most famous – and insidious – of all invasive species in Ontario. They are such a serious problem that millions of dollars are spent each year to bring them under control.
This fish parasite was native to the Atlantic Ocean, but was documented in Lake Ontario as early as the late 1830s, said Chris Sierzputowski, an aquatic science technician with the Department of Fisheries and Oceans, Sea Lamprey Control.
The construction of the Welland Canal in 1829 removed the natural block of Niagara Falls, and from there lamprey began to move into the Great Lakes.
“At one time in the upper Great Lakes, Huron and Superior had viable lake trout fisheries,” Sierzputowski said. “They were harvesting almost 15 million pounds of lake trout a year. And within a decade that 50 million went down to 300,000 pounds.”
The lamprey infestation and overrun was so bad in the first few years that in some areas you couldn’t catch lake trout at all, Sierzputowski said.
Today, the lamprey is controlled on both sides of the border through a binational effort.
Sierzputowski said the main method of control is the application of lampricide TFM which targets sea lamprey larvae in nursery tributaries.
At the concentrations used, TFM kills larvae before they develop deadly mouths and migrate to lakes to feed on fish.
However, Sierzputowski said the war against the invasive lamprey can never end, as it is a very resilient pest.
“We have a very broad mandate, and if we’re going to treat all five Great Lakes, there are over 400 streams that produce lamprey,” he said. “And every year we treat between 60 and 70. So it’s a huge job and we only have a short window.”
While the lamprey looks like what it is – a prehistoric pest that could star in its own horror movie – most invasive plants look very different. Purple loosestrife is a prime example.
One of the most easily recognized characteristics of purple loosestrife is its square, ridged stem.
A single loosestrife plant can produce up to 30 stems from a central root mass and the flowers are attractive in moist areas and ditches where they thrive.
Yet for Jessie McFadden, a watershed stewardship technician with the Lakehead Region Conservation Authority (LRCA) in Thunder Bay, Ont., purple loosestrife is enemy number one.
Loosestrife can negatively affect both wildlife and agriculture and displace native flora and fauna, eliminating food, nesting sites and shelter for wildlife, McFadden said.
“Invasive plants are considered one of the biggest threats to Canada’s biodiversity, and they pose a huge threat to our native plants,” McFadden said.
“Native plants are native to our forests, our shores or our wetlands. These are the plants that have been here for thousands of years. We care about these so much because they are the plants that our bees, insects , birds and wild animals have co-evolved over the years.”
McFadden said purple loosestrife can quickly take over an ecosystem, thanks to its ability to produce nearly three million seeds each year per plant.
They love to move to places where there has been a bit of human disturbance, so they may start in ditches and then they may move to wetlands and shorelines.
Many invasive species can also take a boat ride and find new places to settle.
“We also see waterways as a huge transport route for invasive species,” she said. “Seeds and planting material like to travel down this wet highway, then take root on the shore along the way.”
A big part of the LRCA’s job is to raise awareness of the problem of invasive species, she said. That’s why they promote public stewardship projects and involve people in the solution. “We like to take people out for a few volunteer days to pull up these plants, you know, wrap them in garbage bags, and then kill them in the heat of the sun,” she said. “We also do quite a bit of education.”
emerald ash borer
Although not as pretty as the purple loosestrife, the emerald ash borer sports a unique metallic body and is a relatively benign-looking beetle.
However, this invasive species has hit ash trees across North America, killing millions in southwestern Ontario and the Great Lakes states.
The emerald ash borer is native to northeast Asia and feeds on ash tree species. Females lay their eggs in crevices in the bark of ash trees and the larvae feed under the bark of ash trees to emerge as adults in one to two years.
Adult beetles move slowly across the landscape, but humans can spread the exotic insect over long distances by moving infested firewood, logs and nursery stock to other areas, said Taylor Scarr, director Integrated Pest Management for the Great Lakes Forestry Center in Sault Ste. Mary Ont.
While Scarr said the boreal forest is resilient, the emerald ash borer poses a threat.
He said the beetle is already in Thunder Bay and Winnipeg, and he said evidence shows cold northern weather won’t slow the invasive borer’s movement.
“Two scientists from the research lab here in Sault Ste. Marie just published a paper last week showing that this insect tolerates really really cold temperatures, down to -50 degrees Celsius,” Scarr said. “So that tells us that the insect will survive in northern Ontario and will survive in Winnipeg. It will survive in Saskatchewan, Alberta, Edmonton and Calgary, and a lot of those cities have a lot of ash.”
As is the case with most invasive species, Scarr said there was little chance of completely eradicating the creature.
He said there is an insecticide available and many municipalities use it to keep trees alive.
Scarr said work is also being done with parasitoids, which attack and kill their host.
He said they were looking at a tiny insect from the borer’s home range in China that is the size of a peppercorn, but has no stinger.
“One parasite attacks the egg and two parasites kill the larvae under the bark,” Scarr said. “So these releases have taken place all over Ontario and Quebec, New Brunswick and Nova Scotia. To reduce the impact of the insect.”
Scarr said work like this is time-consuming, but he hopes it will at least help reduce the emerald ash borer population and keep some ash trees in the landscape.