Why should we care about invasive species?

This past week was Invasive Species Awareness Week in Canada.

It is a collaborative campaign focused on raising awareness about 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 make? To answer those 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 bio-diversity.

Sea lamprey

If you have ever gone fishing on Lake Superior or Lake Huron and caught a lake trout, there's a reasonable chance that fish had a circular scar on it.

Those scars are made by sea lamprey, perhaps the most famous – and insidious – of all the invasive species in Ontario. They are such a serious problem that millions of dollars are spent annually to keep 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 the lamprey began the move throughout the Great Lakes.

"At one time in the upper Great Lakes, both Huron and Superior had viable lake trout fisheries," said Sierzputowski. "They were harvesting almost 15 million pounds of lake trout annually. And within a decade, that 50 million went down to 300,000 pounds."

The infestation and population overrun of lamprey was so bad in the early years, that in some areas  you could not catch any more lake trout at all, Sierzputowski said.

Today, the lamprey is fought on both sides of the border thanks to a bi-national effort.

Sierzputowski said the primary method of control is the application of the lampricide TFM that targets sea lamprey larvae in nursery tributaries.

In the concentrations used, TFM kills larvae before they develop lethal mouths and migrate to the lakes to feed on fish.

However, Sierzputowski said the war on invasive lamprey can never stop, as they are a very resilient parasite.

"We have a very large mandate, and if we have to treat all five Great Lakes, there is over 400 streams that produce lamprey," he said. "And annually we treat anywhere from 60 to 70. So it's a huge job and we have only a short window."

Purple Loosestrife

While lamprey look like what they are – a prehistoric parasite that could star in its own horror movie – most invasive plants come across quite differently. The purple loosestrife is a prime example.

One of the most easily recognizable features of purple loosestrife, is its ridged, square stem.

A single loosestrife plant can produce up to 30 stems growing from a central root mass and the flowers look attractive in the wetlands and ditches where they thrive.

Yet for Jessie McFadden, the watershed stewardship technician for the Lakehead Region Conservation Authority (LRCA) in Thunder Bay, Ont., the 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 Canada's greatest threats to biodiversity, and they pose a huge threat to our native plants," said McFadden.

"Native plants are indigenous to our forests or shorelines or wetlands. These are the plants that have been here for thousands of years. We care about these ones so much because it's the plants that our bees, bugs, birds and wildlife have co-evolved with over the years."

McFadden said purple loosestrife can swiftly take over an eco-system, thanks to its ability to produce almost three million seeds each year per plant.

They love to move into places where there's been a bit of human disruption, so they might start off in ditches and then they might move into wetlands and shorelines.

Many invasive species can also take a ride on a boat and find new places to set up shop.

"We also see waterways as a huge transport route for invasive species," she said. "The seeds and reproductive material like to travel down that moist highway and then take root on the shoreline down the way."

A big part of the work of the LRCA is to raise public awareness of the problem of invasive species, she said. That's why they promote public stewardship projects and get people involved with the solution. "We love to get people out for some volunteer days pulling up these plants, you know, bundling them up in garbage bags and then killing them off under the heat of the sun," she said. "We also do quite a bit of education."

Emerald Ash Borer

While not as pretty as purple loosetrife, the emerald ash borer does sport a unique metallic body and is a relatively benign looking beetle.

However, this invasive species has laid the smackdown on ash trees across North America, killing millions of them in southwestern Ontario and the Great Lakes states.

The emerald ash borer is native to north-eastern Asia and feeds on ash species. The females lay eggs in bark crevices on ash trees, and larvae feed underneath the bark of ash trees to emerge as adults in one to two years.

The adult beetles move slowly through the landscape, but humans can spread the exotic insect long distances by moving infested firewood, logs, and nursery stock to other areas, said Taylor Scarr, the director of Integrated Pest Management for the Great Lakes Forestry Centre, in Sault Ste. Marie Ont.

While Scarr said the boreal forest is resilient, the emerald ash borer poses a threat.

He said the beetle is already found in Thunder Bay and Winnipeg, and he said evidence shows the cold weather of the north will not slow down the movement of the invasive borer.

"We just had two scientists out of the research lab here in Sault Ste. Marie publish a paper last week showing that that insect is tolerant to really, really cold temperatures, down to –50 Celsius," said Scarr. "So that tells us the insect will survive in northern Ontario and survive in Winnipeg. It will survive in Saskatchewan and in Alberta and 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 is little chance to completely eradicate the creature.

He said there is an insecticide available and many municipalities are using that to keep the trees alive.

Scarr said there is also work being done with parasitoids, that attack and kill their host.

He said they are looking at a tiny insect from the borer's home range in China that is the size of a grain of pepper, but they don't have a stinger.

"One parasite attacks the egg, and two parasites kill the larvae under the bark," said Scarr. "So those releases have happened across Ontario and into Quebec, New Brunswick and Nova Scotia. To reduce the impact of the insect."

Scarr said work like that takes a long time but he hopes it will at least help dampen the emerald ash borer population and keep some ash trees on the landscape.