Beware of Invasive Species

By Matt Thomson

First off, what is an invasive species? An invasive species is considered to be non-native alien species that causes harm in their introduced environment, reproduces aggressively and their predatory behaviour outcompetes the native species. They alter ecosystems and drive extinction of other species therefore reducing biodiversity across our country. Invasive alien species are classified in multiple categories from fish, invertebrates, pathogens, terrestrial & aquatic plants, insects and wildlife. It’s important to note there can be introduced alien species that don’t pose a threat to local ecosystems due to multiple factors ranging from reproduction challenges or available food sources. These destructive invasive species cause damage to our trees, reducing our shade canopies and habitat for birds, bats and a long list of other living things while creating a ripple effect across food chains in the natural world. They impact our waterways by reducing safe boat navigation, clogging propellers and creating undesirable swimming conditions. Our agricultural activities are affected through expensive herbicide & pesticide treatments that can drive up the affordability of crop foods. The economic impact for us is massive while running into the billions of dollars, and that doesn’t account for management expenses along the way.  

From a global perspective, there have been 37,000 alien species reported and about 5,300 of those are considered invasive. A single alien invader on an island ecosystem can result in full extinction of its native species. Again, threatening economies of other countries by reducing food & water security but also negatively impacting human health and cultural identities. A few years ago it was estimated that these biological invasions had cost more than $423 billion annually (this is before inflation worsened). This staggering dollar figure doesn’t account for management or battling these invasive species. 

So what’s driving the spread of invasive species? Many of these species are introduced unintentionally through the vast network of global trade imports & exports with weak security measures in place. They can hitch a ride on a cargo ship (Zebra mussels) or get caught up in the logistics of transporting a palette of goods (Spotted Lanternfly). Sadly some are introduced intentionally by us humans, through various tourism activities such as bait fishing (Rusty Crayfish) and that’s the reason why it’s important to purchase your fishing bait locally. We buy colourful exotic species for our aquariums & terrariums then realize shortly after it’s not what we expected or difficult to care for. The most dangerous thing we can do is release these unwanted pets outdoors. As harmless as a small goldfish can be they can grow into monstrous feeding fish.  

You may be asking why so much money is spent on something that doesn’t matter to you. I can tell you that it does matter. While the money being spent on management tools can be a “drop in the bucket” compared to the economic impacts, the cost of inaction is something that we’d rather not find out. It’s critical that all levels of government work together and encourage all municipalities & private citizens to get involved in the fight against the more than 450 species across Ontario. Early detection is extremely important and most effective to soften the burden of invasive species. It’s as simple as monitoring the trees on your property, inspecting the shoreline at the cottage and reporting or asking questions about anything suspicious you may encounter, especially if you witness a large group of something unknown. 

The next question is, how do we eradicate the invaders that threaten the local landscape, like our yards and under our docks? First task is to determine what invasive species are present on your property. You may want to seek advice from a local expert like a horticulturist or ecologist. Utilize online forums such as iNaturalist to help you acquire an identification. Removal methods can vary depending on the invader. It may require extreme caution such as the phototoxic sap of Giant Hogweed. A sound management plan does require a certain commitment as most plant removals, for example, typically take multiple years. Don’t be alarmed if it grows back next year, that’s their aggressive nature but persistence is key on our part. Similar to picking up roadside trash, an hour or two each time can make a huge difference in forming a dent against the biological invasion. To learn more about invasive species and how you can help, be sure to check out these websites; and 

Matt Thomson is a local conservationist based in Severn and enjoys engaging the community through citizen science events & activities. You can find him on Instagram or Facebook, @ardtreanature