Even though scientists are generally thrilled about finding new species, it can also cause them to worry. This is the case when they find that non-native organisms have been introduced into an ecosystem. These newcomers are called exotic species.
Results gathered from research conducted in Ontario show that 91% of these newcomers are unable to live or nest in their new environment.  Species that are able to do so often cause great damage to the ecosystem.
Some exotic species are described as "invasive". These species are able to thrive and spread, usually because food is abundant, and there are few (if any) predators, illnesses or parasites in the new habitat.
Several of these invasive species reproduce prolifically. For example, each mature purple loosestrife plant produces 2 million seeds every time it blossoms. Eurasian water milfoil is able to grow from seeds, and fragments of root and stem are able to take root and grow. [3, 4, 5, 6]Strong Competition
Exotic species are often able to supplant native species, thereby leaving the native species with fewer nesting sites and food resources. In downtown Ottawa for example, the flowering rush has multiplied along the shorelines of the Rideau River at the expense of native aquatic plants.
In addition, some exotics can harm a native species directly. Zebra mussels, for example, often fasten themselves in clusters on the shells of native mussels. The unfortunate animals are thus prevented from breathing, feeding and moving, and so they die.
Exotic species spread through several means. Some spread naturally with the current, as seen with fragments of Eurasian water milfoil or zebra mussel larvae. They can also be transported to other bodies of water in bait buckets or live wells, or attached to boat hulls and propellers.
Questions about exotic species? Call the exotic species hotline of the Ontario Ministry of Natural Resources and the Ontario Federation of Anglers and Hunters: 1.800.563.7711.
|Last Update: 2008-11-20|
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