Ecoscience: Snail Darters and the Importance of Ecosystems

Arguments over the protection of individual plant and animal species often fail to take the importance of ecosystems into account.

| May/June 1979

Many people seem to wonder whether ecologists have gone off the deep end in the struggle to protect endangered species. We are often asked, "Isn't it preposterous that the existence of such an insignificant fish as the snail darter should be allowed to stop a public works project like the TVA's Tellico Dam, a structure in which millions of taxpayers' dollars have already been invested?"

Our answer is always the same: The Tellico Dam should have been stopped dead in its tracks even if it had been a very important and worthwhile project (which, according to much testimony, it wasn't). In fact, even if the TVA had followed the letter of the law instead of trying to evade existing legislation, the dam could not have been allowed to destroy that one little species of fish.

As many of you are aware, the ecological systems of our planet constitute a gigantic life-support apparatus that must function smoothly if our civilization is to persist. We mentioned a few of the "public service!' functions in our column on the tropical forests, but let us reiterate the importance of ecosystems:

They maintain the quality of the atmosphere, help to stabilize weather, provide food from the sea, control the vast majority of potential crop pests and carriers of human disease, generate and maintain soils, recycle nutrients essential to agriculture, and dispose of our wastes. Perhaps even more important, however, such systems also preserve a vast genetic "library" on which we can draw for—among other things—new domestic plants and animals, spices and medicines, organisms for scientific research, antibiotics, and so on.

Now, if everything about the life-support apparatus were understood, all would be well. We would be able to predict the consequences of fiddling with any part of it, and in particular to understand what would happen if any one element were removed from the ecosystem.

We know that many, if not most, ecosystems are quite robust, that they will recover from various sorts of insults, and even from the extinction of populations and whole species! The fossil record reveals that the extinction of populations and species has been a regular feature of the evolutionary process on this planet for hundreds of millions of years. In the past century many extinctions have been observed that have not, at least in the short term, seemed to have major deleterious effects on their respective ecosystems.

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