An invasive species is a non-native plant, animal or other species which has been introduced into an area, and which may dominate the nutrients and habitat of the native species normally present. Invasive species are a particular threat in Canada, with the Great Lakes basin alone having more than 180 known invasive species that have arrived in the basin since the 19th century (1). Introduction of non-native species to an area can be natural, for example, a migratory bird carrying a seed over long distances, but these harmful plants are more often deliberately introduced by humans. 

One example of well-meant introduction by humans is the Autumn Olive, which was introduced in southern Ontario in the 1970s by land managers in the belief that this dense thicket would provide a habitat and protection for local wildlife. In reality, Autumn Olive creates a shrubbery so dense it shades plants in need of sunlight, and leeches the soil of needed nutrients, making it unsuitable for native plants and giving other invasive plants the ability to overpower the weakened native populations (2).

A prominent aquatic invasive species in Canada is Eurasian Milfoil, one of the most widely distributed aquatic invasive species in North America. Originating in Europe, Asia, and Northern Africa, it is suspected that it was inadvertently transported on the hulls of ships coming from those regions in the 1800s. It is a quickly spreading perennial plant, overshadowing native plants, which causes them to deteriorate, resulting in a lack of oxygen in the water which may affect fish populations (3).

Although invasive species are still a large and prominent issue in Canada, programs, events, and initiatives to prevent and/or offset the spread of invasive species are gaining ground, such as the annual Invasive Species Forum hosted by the Invasive Species Centre, which raises awareness about invasive species issues, research, and advances in prevention and management in Canada and the United States of America. Events such as this not only provide an area of knowledge sharing for industry professionals, but also a learning platform for the general public in order to foster a culture of mindfulness, aiding prevention of the spread of invasive species to ensure protection of biodiversity and ecological stability.

Sources:

1. The Canadian Encyclopedia

https://www.thecanadianencyclopedia.ca/en/article/invasive-species-in-canada-animals

2. Nature Conservancy Canada

https://www.natureconservancy.ca/en/what-we-do/resource-centre/invasive-species/

3. Ontario’s Invading Species Awareness Program

https://www.invadingspecies.com/invaders/aquatic-plants/eurasian-water-milfoil-2/

Photo: Small, feathery Eurasian milfoil leaves and long, vine-like stems entwine a Water lily flower and lily pads in a Western Quebec lake. Photo by F. Brown