Photo By:

Invasive Species

May 27 2009

This year’s theme for the International Day for Biological Diversity has put the world on high alert – we’re under alien attack. Not aliens of the Sigourney Weaver variety, but “invasive alien species”. Invasive alien species refer to many plants, animals and micro-organisms that have spread beyond their natural range into new locations as a result of human activity. 


Aliens are nothing new; early European explorers and settlers were one of the first culprits to bring foreign species with them such as stowaway Norway rats and numerous diseases. However, in 2009, our means of transportation has increased exponentially, thus allowing the spread of invasive species to occur at an astounding rate. Whether these species enter a country intentionally (70 live Shanghai hairy crabs in a traveller’s suitcase) or accidentally (zebra mussels spread when ships empty their ballast in Canadian waters), these tourist species are causing a ruckus. The UN Convention on Biological Diversity agrees that these “alien” plants and animals constitute "one of the greatest threats to biodiversity, and to the ecological and economic well-being of society and the planet."


Alien species have no qualms about making themselves at home on foreign soil. When they’re not competing for resources, they can be found killing and feeding on native plans and animals, making habitats uninhabitable for the plants and animals that previously lived there and weakening the gene pool by breeding with native species.


Conservation biologists have globally ranked invasive alien species as the second most serious threat to species at risk after habitat destruction. Currently, more than one-third of BC’s native freshwater fish are considered at risk and with the introduction of invasive alien species, their futures remain uncertain. Introduced crayfish rendered extinct four unique species of stickleback fish within the last few years, while the largemouth bass is jeopardizing the future of the local cohabitants. The largemouth bass’ knack for exploiting his environment has made life for two of BC’s endangered species, the Salish sucker and Nooksack dace, challenging. And if the past is any predictor of what is to come, the futures of many local fish aren’t looking so bright; over 70 per cent of this century’s extinctions of native freshwater species were caused by invasive alien species.


To fight the invasion and support biodiversity we must first educate ourselves. There are many things you can do to support biodiversity (aside from choosing not to pack crabs you picked up on your exotic vacation). In Vancouver’s Stanley Park, volunteers pull out the invasive English ivy that creeps its way throughout the park, causing harm to many of the local plants it comes in contact with. What must happen next is the implementation of law to protect our already vulnerable at-risk species from these unwanted guests. Whether or not the invasive alien species were introduced intentionally or accidentally, a law is essential is protecting our at-risk species and ensuring not only their survival, but recovery.


It is difficult to complete eliminate the invasion of alien species, however if we all pitch in and do our part, we can look forward to strong and vibrant ecosystems, sans Shanghai hairy crabs. To learn more about what you can do visit

Inspired by this article? Share it with others.

Your Comments

  • Your thoughts and opinions are welcome. Be the first to comment on this article.

Post a Comment

Provide your comments on this blog entry, using the form below.

Remember my personal information
Notify me of follow-up comments?