Invasive Alien Species – A Threat to Biodiversity
Imagine Ontario’s landscape without ash and maple trees, or the Great Lakes without lake trout. However, we don’t have to imagine Ontario without the American elm or American chestnut. Failure to stop the spread of invasive alien species – organisms from other parts of the world – has meant that today’s children no longer walk down streets lined with American elm or collect wild sweet chestnuts. These are now only memories. Today, the emerald ash borer could cause the loss of one billion ash trees in Ontario, and the Asian long-horned beetle could bring about the loss of our national symbol, the maple tree. Residents of Essex County already know what it means to have no ash trees and residents of Vaughan, no maple trees. The urgent question today is: will Ontario’s woodlands, wetlands and Great Lakes give way under the continuous onslaught of invasive alien species?
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What are invasive alien species?
Alien species, also known as exotic or non-native species, are organisms such as birds, mammals, fish, insects, plants, molluscs or micro-organisms from other countries or regions that have been introduced into habitats where they are not naturally found, either today or in the past. Most alien species do not thrive, since they are poorly adapted to their new habitat. But a few species succeed and thrive, and these are called “invasive alien species.” Once established, invasive alien species may out-compete native species for food and habitat, causing native species to move to another area, weaken or die.
They may prey on native plants or animals, resulting in negative effects on other levels of the food chain. They may also cause an infection in a native species, weakening or killing it. In the worst case, invasive alien species can wreak ecological havoc and threaten biodiversity, potentially resulting in a scenario called “invasional meltdown.”
Humans have often provided the means for these species to travel from one region to another. Some hitch a ride on our vehicles or footwear, or in our belongings. Others have used canals to move from one waterbody to another. Some of the most ecologically destructive invasive species have been dumped into the Great Lakes by ships adjusting their ballast, and others have arrived in wood packaging used to transport goods around the world. Some alien but not necessarily invasive species have been deliberately introduced into Ontario, often for economic reasons. However, some of these species have established populations in the wild through deliberate or accidental human activity, and are disrupting food chains and displacing native species. With today’s lifestyle and global trade, potentially every person, mail package, vehicle, plane, or watercraft entering Ontario or traveling from one region of Ontario to another could provide an efficient means of dispersal.
Why should we be concerned about invasive alien species?
Invasive alien species can reduce native biodiversity in an area. American chestnut and American elm trees are no longer common in southern Ontario forests because of devastation by chestnut blight and Dutch elm disease, fungal organisms, respectively, from Asia and Europe. Several ecologically important Great Lakes fish populations, including lake trout and whitefish, collapsed in the 1950s in large part due to an invasion by the sea lamprey. Many native birds, including woodpeckers, purple martins and bluebirds, were displaced by the European starling. Experts believe that, after loss of habitat, invasive species are the second most important cause of the decline of native species.
The decline of native species and native ecosystems is, in part, an ethical issue. Significant components of our natural heritage – species and ecosystems that have developed since the last ice age – are being lost, and hence we are losing our future legacy. Since the 1800s, over 160 alien species have invaded the Great Lakes Basin. Sometimes called biological pollutants, they are unlike many chemical pollutants, which eventually dilute or degrade: invasive alien species reproduce and spread.
But the damage to native species by alien species is also an economic issue. The survival of Ontario’s forestry, fishery and tourism industries depends on our natural resources. Not only have invasive alien species devastated commercially important tree and fish populations; they have also weakened and destroyed industries. Costly control and containment measures to maintain the resource have been required, and products have been made unusable through disease. Export markets have disappeared overnight, since under international law, countries can bar the entry of products from regions infested with invasive alien species.
In June 1992, Canada signed the Convention on Biological Diversity – a United Nations treaty – and thus agreed to work to prevent the introduction of invasive alien species and to control and eradicate those that threaten ecosystems, habitats or species. Under the umbrella of the Canadian Biodiversity Strategy, a National Invasive Alien Species Strategy and Action Plans are being developed to address prevention, early detection, rapid response and containment, eradication and control of invasive alien species at the national level. The Ministries of Natural Resources and Agriculture and Food are active participants under the overall leadership of the federal government.
At the provincial level, MNR has a number of initiatives that address specific concerns, such as zebra mussels and purple loosestrife. MNR has also recently posted a decision on the Environmental Registry for a regulation to prohibit the buying or selling of live Asian carps, snakeheads and gobies. In fiscal year 2003/2004, MNR has committed $475,300 to fund 10 projects, including examining the impact of invasive alien species on biodiversity and the use of biocontrols. MNR is also a member of the provincial Introductions and Transfers Committee, which is responsible for reviewing proposed non-routine introductions and transfers of aquatic organisms for stocking and aquaculture. OMAF also has several initiatives specific to crop pests such as pea leafminer and leek moth, farmed deer and elk, and microbial and viral hazards such as the West Nile virus.
Why Ontario needs a strategy for invasive alien species
Many scientific, economic and political challenges must be overcome if the rate of introduction of invasive alien species is to be slowed, and if the existing invasive species are to be contained and eradicated.
- Prevention measures have gaps and are often not enforced.
- Government resources to detect, contain and eradicate these species are limited.
- Government funding of initiatives is very limited, considering the potential losses.
- Information about invasive alien species – their behaviour, preferred food and habitat, and control and eradication – is often lacking or non-existent.
- Containment and eradication measures are often controversial, particularly the use of biocontrols (such as another alien species) and of chemicals.
- Knowledge of our native ecosystems – species composition and interactions – is often dated or lacking.
- Property owners and local residents may be unaware of how their behaviour can undermine containment measures and may resent drastic measures, such as eradication of all trees within an area.
In our 2002/2003 annual report, we recommended that MNR draft an invasive species sub-strategy as part of a provincial biodiversity strategy, urging that the sub-strategy should include “a clearly identified vision, objectives, detailed courses of action, measurable targets and public reporting requirements.” The invasive species sub-strategy should provide an Ontario perspective on invasive alien species, reflecting the province’s social, economic and ecological values. In its response to the ECO’s recommendation, MNR re-affirmed its commitment to addressing specific goals and directions, but did not acknowledge any need for a provincial biodiversity strategy or an invasive species sub-strategy. However, a sub-strategy regarding invasive species is required to ensure that all parties have the same priorities, that appropriate and well-co-ordinated rules are in place to prevent entry of invasive alien species, that these species are detected upon arrival, that funds and resources are readily available, and that effective control and eradication measures are implemented without delay.
Moreover, legislation is also required to provide clear allocation of roles and responsibilities for federal, provincial and municipal agencies regarding invasive alien species, since there are no federal or provincial laws that specifically empower the different levels of governments to regulate these species. Under the Canadian Constitution, the federal government can enact laws over environmental matters that have inter-provincial or international effects related to shipping, inland fisheries and canals. Provincially, the Ontario Ministry of Natural Resources has responsibility for forestry and local fisheries. The federal Canadian Food Inspection Agency has lead responsibility for the invasive alien species that affect agriculture, while the Ontario Ministry for Agriculture and Food provides support. Municipalities are responsible for the trees on municipal public land. Despite the existing legislation and various policies and codes used to guide decision-making, invasive alien species continue to enter and spread across the province. In view of the enormous value of our natural resources that are at risk, it is essential that the Ministry of Natural Resources step up to all of its responsibilities for protecting Ontario from invasive alien species. The strategy and legislation must ensure that not only commercially significant natural resources are protected; it must also ensure that all of Ontario’s ecosystems are protected. Targeting specific invasive alien species without the context of a provincial strategy provides no assurance that scarce human and financial resources are appropriately deployed.
| This is an article from the 2003/04 Annual Report to the Legislature from the Environmental Commissioner of Ontario. |
Citing This Article
Environmental Commissioner of Ontario. 2004. "Invasive Alien Species - A Threat to Biodiversity." Choosing our Legacy, ECO Annual Report, 2003-04. Toronto, ON : Environmental Commissioner of Ontario. 47-52.
