Aquatic invasive species (AIS) pose a significant threat to the health and biodiversity of all rivers in Canada, including designated Canadian Heritage Rivers. These non-native species can disrupt ecosystems, outcompete native species, and cause extensive economic and environmental damage.
Understanding the Threat
Aquatic invasive species such as zebra mussels, Asian carp, and European Water Chestnut have been introduced to Canadian waters through various means, including ballast water discharge from ships, recreational boating, and the aquarium trade. These newcomer species are often generalists who fill an ecological niche left empty by longer-established species due to human disturbance. Once established, invasive species can spread rapidly, altering habitats and food webs, and making it difficult for native species to survive.
AIS concerns in Heritage Rivers
Image: Two staff engage in monitoring projects on the Athabasca River.
Photo Credit: Parks Canada
Invasive species are threatening Heritage Rivers across Canada. For example, invasive knotweed is eroding riverbanks, damaging salmon habitats, and making riparian ecosystems uninhabitable for native species. Unconfirmed reports indicate that the Cowichan River has over 100 knotweed infestations. Similarly, the French River is at risk of invasive species expansion, especially phragmites, because of its proximity to major highways like the 400 and its heavy usage by residents and cottagers.
In the Hayes River watershed, zebra mussels and potentially spiny waterfleas are a growing concern due to human-mediated transfer. Zebra mussels have been detected in two sites on the Echimamish River, part of the Nelson River Aquatic Invasive Species Control Zone. Meanwhile, the Thames watershed faces threats from both aquatic species, like the Round Goby, which is nearing the habitat of the endangered Eastern Sand Darter, and new diseases such as Beech Bark Disease and Oak Wilt along its shorelines.
Likewise, the Upper Restigouche region is on alert after zebra mussel DNA was found in Matapedia Lake, indicating that the species may have already entered the system, which would have severe consequences for river biodiversity.
Control and Eradication Efforts
Image: A closeup image of water monitoring equipment.
Photo Credit: Parks Canada / Chris Reardon
To manage and mitigate the impact of AIS, a multi-faceted approach works best. This includes:
- Early Detection and Monitoring: Regular monitoring of water bodies helps in the early detection of invasive species. This allows for swift action to prevent their spread.
- Public Awareness and Education: Educating the public about the risks of AIS and how they can help prevent their spread is crucial. This includes promoting practices such as “clean, drain, dry” which involves cleaning boats and equipment before moving them between water bodies.
- Biological Control: Introducing natural predators or competitors can help control invasive populations. For example, certain fish species can be used to control invasive plant growth.
- Chemical Treatments: In some cases, carefully controlled chemical treatments are used to eradicate invasive species. These treatments are applied in a way that minimizes harm to native species and the environment.
- Physical Removal: Manual or mechanical removal of invasive species, such as hand-pulling invasive plants or using barriers to prevent the spread of invasive fish, is another effective method.
Success Stories
Several success stories highlight the effectiveness of these strategies.
In 2014 and 2015, an invasive aquatic plant called European Water Chestnut was discovered in the Rideau Canal. Ducks Unlimited led a control program until 2020, after which Parks Canada took over and continued monitoring and control activities in 2021 and 2022. Significant population decreases have since been observed in the system.
On the Koksilah River, a team of volunteer biologists has been successfully controlling knotweed for the past eight years, advocating for similar efforts on the Cowichan River through the Cowichan Stewardship Roundtable and Cowichan Watershed Board.
This past May, the Essex Region Conservation Authority (ERCA) released biocontrol agents to suppress invasive Phragmites at the Collavino wetland on the Detroit River. This biocontrol initiative was part of a broader effort to manage the spread of this highly invasive wetland grass, which has severely degraded many ecosystems across North America.
This year, Jasper National Park launched its aquatic invasive species (AIS) prevention program around the Athabasca watershed. The program features inspection and decontamination stations for watercraft, a permitting system, and roving education by Parks Canada staff, who engaged with over 3,000 visitors on AIS prevention measures. Aquatic invasive species monitoring was also conducted in Banff, Yoho and Kootenay national parks.
Image: An underwater image of a net, as scientist monitor for aquatic invasive species in Banff National Park.
Photo credit: Parks Canada/ Sophie Deschamps
The Grand River Conservation Authority (GRCA) treated approximately 20 hectares of land across four properties to control invasive Phragmites, focusing on protecting key natural areas. In the Humber River region, community engagement events included efforts to remove invasive species.
Finally, in late October of this year, Algoma University completed the St. Mary’s River Tributary Enhancement Project. Funded by the Ontario Community Environment Fund, the project aimed to improve water quality, remove invasive species, and restore wildlife habitat along flood control channels in Sault Ste. Marie, Ontario. These initiatives underscore the ongoing commitment to protecting Heritage Rivers from aquatic invasive species.