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Problems Caused by Introduced Species

written by: JenniferB•edited by: Niki Fears•updated: 9/15/2009

What are introduced species? Also known as exotic species, these are plants or animal life that is introduced from a foreign ecosystem. This can cause biodiversity loss and other damage to local ecosystems.

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    The Problems with Introduced Species

    According to the IUCN, the biggest threats to biodiversity are those related to human activity. Of those threats, introduced species are a significant cause of biodiversity loss. Introduced species, also referred to as “exotic species”, include organisms that are brought to a region where they previously had never been found. Introduced species are often dangerous to native species because they have not evolved together and therefore compete for food and shelter.

    For example, many birds on oceanic islands are unable to defend themselves from introduced ground hunters. Hawaii is home to one classic example of how catastrophic the results of introduced species can be. The Pacific black rat, caused the extinction of honeycreepers, an endemic bird, shortly after it was brought to the island, by raiding eggs from the birds’ nests. This bird is now extinct.

    How else do introduced species threaten those that are native? Introduced species may also compete with native species for resources, causing populations of the native species to decline. For example, zebra mussels in the Great Lakes crowd out native mussel species as well as other organisms that filter algae from the water. States that border the Great Lakes have spent millions of dollars to try and manage the many problems that zebra mussels cause for native species.

    It is also important to realize that when introduced species crowd out native species, it is not only their direct competitors that suffer. Other species that rely on the struggling natives may decline as well. Often scientists and resource managers are overwhelmed by the multiple indirect problems caused by exotic species.

    The more accessible travel becomes, the more humans continue to move species around the planet. As tourism as well as global trade in agriculture and other goods continues to expand, the number of species introductions is likely to increase over the next century without a considerable effort to prevent them.

    How Can You Do to Help?

    What can you do to prevent the introduction of new species? Here are a couple of easy steps you can do to help prevent the introduction of new species:

    • Don’t transplant flowers or other plants into your yard, unless it is found growing as a native species in your area. Flowers purchased at the local nursery should always be a safe bet! If you’re not sure, contact a master gardener in your area.
    • When boating, make sure that you clear the plants and attached organisms (mussels or barnacles) off of the bottom of your boat after you take it out of the water. If you don’t, you may transport them to another body of water, possibly introducing an exotic species to a new location.

Human Causes of Extinction

According to the IUCN, the biggest threats to biodiversity are those related to human activity. This series explores some of the different types of human activity that are having devestating effects on a variety of species.
  1. Problems Caused by Introduced Species
  2. Human Causes of Extinction: Overexploitation
  3. How Human Activities Contribute to Coastal Ecosystem Decline
  4. Habitat Rehabilitation: The Answer to Human Activity