Saturday, February 28, 2009

Invasive Species and Ecosystem Service Loss

Yet another species’ existence is threatened by a non native to the ecosystem, recently introduced invasive. We know about the potential loss of baseball bats (ash trees) as the emerald ash borer mines its way through the forests of the United States and Canada (Maryland, Pennsylvania, Virginia, Ohio, Indiana, Illinois, Michigan, Ontario), and possibly the region around Moscow. Now we learn about a killer isopod, an invasive species perhaps introduced as a hitchhiker on the trade routes with our Asian markets. The target, a west coast mud shrimp (Upogebia pugettensis), of the parasitic exotic, “blood-sucking bopyrid isopod Orthione griffinis”, does not have the cache of a 90 foot tall, dead tree crashing through the roof of a suburban home. And of course the litany of species extinction delivered one species at a time results in a dreary resignation or indifference to the loss. The reaction to the species homogenization tends towards the ‘who-cares’ model. picture above:
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Keeping to the theme we have the “…zebra mussel (Dreissena polymorpha) (which) is a small, non-native mussel originally found in Russia.” This non green card bearing visitor causing “…the near extinction of native American unionid clams in Lake St. Clair and in the western basin of Lake Erie.” And to add to the sense of impending doom, the invasive zebra mussel is now moving west with recreational America.
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Daniel Simberloff offers a sober assessment of biological loss in his article, “Introduced Species: The Threat to Biodiversity & What Can Be Done.” (An original article). A list of loss over time includes:
· GONE: American chestnut and ten moth species that could live only on chestnut trees
o Asian chestnut blight fungus
· GOING: sawgrass
o Australian paperbark tree
· GONE: ten of the eleven native bird species from the forests of Guam.
o brown tree snake

This collect of loss sounds like a chant from the Dies irae and is irritating to those who feel that nature exists as a raw resource to be exploited with no cost. Forests are meant to be logged, bogs drained and paved, mountains mines and leveled, schools of fish caught until extinct, herds of buffalo eliminated for food and sport, and insignificant plants such as Leopold’s Draba verna reduced to the obscurity of no present value.

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