For the amount of damage they cause, invasive species punch above their weight. The spread of invasives can have enormous consequences on natural ecosystems, recreation, and economic industries. Now, a study by a team of international researchers has revealed that the global economic cost of invasive species is as steep as the costs for natural disasters such as storms, earthquakes, and wildfires.
“Invasive species are costly,” says Sarah Rang, the executive director of the Invasive Species Centre, a non-profit that was not involved with the study. “We know in Ontario alone, it’s a $3.6 billion annual cost because of the impacts on forests, fisheries, agriculture, tourism, and recreation.”
Rang points to zebra mussels as a prime example of an invasive species whose actions have led to a big price tag in Ontario. While an individual zebra mussel is smaller than a fingernail, they form vast colonies can spread to form what looks like a large underwater lawn of mussels.
Rang says that zebra mussels are efficient water filters, similar to little aquarium pumps going all day and all night. But their filtering abilities have cascading effects on the ecosystems of Ontario’s lakes. “They can store and change toxins and nutrients like phosphorus, which we know is like fertilizer for aquatic weeds,” says Rang. “There’s really good evidence that says zebra mussels take in water, they filter it, and they change the type of phosphorus that’s available and make it more available for plants and other things to grow,” she says. These little biological filters can lead to an overgrowth of aquatic plants and hazardous algal blooms in Ontario lakes.
But Rang points out that it’s important not to despair or be discouraged when faced with the high cost of invasive species. “There are practical steps that all of us can take to reduce the impacts of invasive species,” she says.
This first is to stop the introduction of invasive species to a new area. That’s the most cost-effective method of dealing with invasive, says Rang. For cottagers, and boaters in particular, there’s a simple motto to remember: clean, drain, dry. As of January 1st, 2022, Ontario has mandated that all boaters must remove or open drain plugs and take all reasonable precautions to remove invasive species on boats and associated equipment before transporting overland. Actions to prevent invasive species spread today will save Ontario money—and frustration—in the future.
The top 5 invasive species that cost us the most
From 2017 to 2019, the Invasive Species Centre surveyed Ontario municipalities and conservation authorities to estimate the costs spent on invasive species. The total estimated costs for invasive species was estimated at $50.8 million per year.
Here are the top five invasive species that racked up the big bucks.
1. Emerald ash borer
This small, wood-boring beetle targets—you guessed it, ash trees. The larvae chew their way through a host ash tree, killing the tree in the process. The damage caused by the emerald ash borer quickly adds up for municipalities and conservation authorities as dead and damaged trees must be removed and replaced.
2. Zebra mussels
Along with their negative impact on freshwater food webs, zebra mussels are known to invade water supply pipes, leading to large repair costs.
3. Spongy moth (a.k.a. the LDD moth)
Unlike the emerald ash borer, spongy moths aren’t so picky about their host tree. The caterpillar stage of these invaders will feed upon the leaves from a variety of hardwood and some softwood trees. They impact the health of forests by stripping their host tree of leaves, impacting the forestry industry as well as tourism.
4. Quagga mussels
Quagga mussels can survive and spread across both hard and soft surfaces, damaging structures such as docks, break walls, and beaches.
A familiar sight along the highways up to cottage country, phragmites is a tall invasive reed that forms thick stands and crowds out native vegetation. Along with the harm they cause to native species, they can block off access to shorelines for property owners, boaters, and fishers.
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