When one speaks of invasive species, what does come to mind?
Almost inevitably for me, it meant disaster for the local ecosystem. It meant having a sledgehammer hitting a pillar supporting a particular food chain down, collapsing the entire local environment down. A slippery slope fallacy I admit but that was the frame of thoughts whenever I came across the term “invasive species”.
I considered nonchalant introduction of foreign species into a local environment as irresponsible. This perspective was nurtured through countless reading of effects of invasive species on local ones.
In a magnificent University of Michigan’s natural science museum which I loved to frequent in Ann Arbor, there was an exhibition dedicated to lampreys. With the University being one of the only 30 sea-grant institutions, it is only right for the University to having at least something on lamprey.
A certain kind of lamprey, especially the one which devastated the trout population in Lake Michigan, looked like a giant leech to me. Attacked fishes would have deep noticeable and disgusting scare on their body. The lampreys were introduced to Lake Michigan after the canals which connect the Great Lakes was completed in the 19th century.[1][2][3]
Another example of invasive species which adversely affect the indigenous species is the snakehead fish. Unlike the lamprey which originated from Lake Ontario which is really not far of Lake Michigan, the snakehead fish came from Asia. Its creepy name matches its seemingly out of this world ability to breathe and walk over land. Its aggressiveness is likely to phase out indigenous species from the local ecosystem.[4]
The introduction of these species always brings about unknown consequences. The fear of the unknown consequences convinced me to subscribe to precautionary principle, a principle which demands scientific proofs to be presented to alleviate concerns for the unknown.[5]
Truth be told, in retrospect, placing all invasive species in a bad light takes a simplistic view of the world. It ignores some of the benefits which foreign species may bring to the local environment. I do believe I have to a large extent mastered over tendency to make sweeping generalization but I never actually gave my preconception of invasive species much thought, until the New York Times published an article about the matter recently.[6]
The article highlights invasive species contribution to diversity. Again in retrospect, surely that is the case if the introduced species do not compete with indigenous ones. Yet, my first reaction to the article was that of shock. The assumption that I held was easily disproved but yet, I overlooked such flimsy assumption.
Nevertheless, this neither mean that I would suddenly take a diametrically opposing viewpoint nor would I abandon the precautionary principle. What the article teaches me is to be more careful of assumptions in matter concerning invasive species in particular and other matters in general. What it really teaches me is to observe the context as well as the individualized effects of the introduction of any invasive species to specific ecosystems.
[1] — [The Lampreys Of Michigan. Michigan Natural Resources (Reproduced by The Native Fish Conservancy). Sidney B. Morker. July/August 2008. (Accessed September 9 2008)]
[2] — See Great Lakes: Ecological Challenge at Wikipedia. Accessed September 9 2008.
[3] — See Lamprey: Relation to human as pest at Wikipedia. Accessed September 9 2008.
[4] — The snakehead fish, a voracious Asian invader that’s been known to breathe out of water and scoot short distances over land, has reappeared in Maryland, state authorities announced yesterday. [A creepy catch of the day. Washington Post. David A. Fahrenthold. April 29 2004]
[5] — See precautionary principle at Wikipedia. Accessed September 9 2008.
[6] — It sounds like the makings of an ecological disaster: an epidemic of invasive species that wipes out the delicate native species in its path. But in a paper published in August in The Proceedings of the National Academy of Sciences, Dov Sax, an ecologist at Brown University, and Steven D. Gaines, a marine biologist at the University of California, Santa Barbara, point out that the invasion has not led to a mass extinction of native plants. The number of documented extinctions of native New Zealand plant species is a grand total of three.
Exotic species receive lots of attention and create lots of worry. Some scientists consider biological invasions among the top two or three forces driving species into extinction. But Dr. Sax, Dr. Gaines and several other researchers argue that attitudes about exotic species are too simplistic. While some invasions are indeed devastating, they often do not set off extinctions. They can even spur the evolution of new diversity. [Friendly Invaders. New York Times. Carl Zimmer. September 8 2004]
