Invasive Species 101

Giant Hogweed

What are invasive species? Invasive species generally are non-native plant, animal or pest species that outcompete native species for resources and dominate space. They may directly kill other species, introduce disease or hybridize with native species. Non-native invasive species typically prefer disturbed habitats, are aggressive, have high reproductive rates, and lack natural predators. Invasive species are spread with the assistance of humans and by animals, wind and water. Visit our Invasive Species Spotlights page to learn about some example invasive species.

How did they get here?

Many non-native species arrived here during European settlement as either intentional or unintentional introductions. Today this is still the case as new species are introduced to and move around North America through modes such as:

  • Accidentally through ballast water transfers from international locations to the Great Lakes, down to small vessels that exchange water from local water body to local water body.
  • Through the baitfish industry and anglers who dump unwanted bait back into waterbodies.
  • Through the horticultural industry; many invasive plants are still unregulated and are sold at local nurseries.
  • Movement of wood products internationally (e.g. emerald ash borer and the Asian long-horned beetle)

Why be concerned about invasive species?

The rapid spread of invasive species has become a major concern worldwide. From an ecological perspective, there is concern about:

  • the displacement of diverse native species;
  • impacts on species that rely on native plants for food, and habitat; and
  • reduced genetic diversity.

In fact, threats posed by invasive species are now considered one of the most serious threats to global biodiversity, as recognized by the UN Convention on Biological Diversity, the International Union for Conservation of Nature, the Invasive Alien Species Strategy for Canada, and the Ontario Biodiversity Strategy.

From an economic perspective, invasive species can have far-reaching impacts and often unseen consequences and associated costs. From increased maintenance associated with cleaning zebra mussels from water-taking pipes in infested lakes, to decreased forest productivity, and reductions in sport fishing opportunities, the costs of invasive species are substantial. A conservative estimate of cumulative annual costs for just 18 species ranges from $13.3 to $34.5 billion federally. Manitoba alone estimates its economic losses due to Dutch elm disease at roughly $30 million, and a single invasive alien thistle species impacting a single crop, canola, carries an annual cost of $320 million on the prairies. Estimates of the cumulative impact of zebra mussels range from $3 billion to $7.5 billion for the Great Lakes.