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Re: Introduction

I don't think that taking some species from a river and then reintroducing them is anything to worry about when our country is crawling with all kinds of introduced species. And even that fact gets some people more upset than they need to be. There is a "rule of 10's" that is a rough guide to predicting the fate of an introduced species. Of every 10 introduced, only one will survive, and of every 10 that survive, only one will multiply so much as to be a concern.

With introduced species that have spread widely or are spreading, the genie is definitely out of the bottle and can't be put back in. The only thing we can do is watch and see what happens. Often it is not so bad as originally predicted. There is a period of evolutionary adjustment, both in the introduced species and in the populations of other species affected by the introduced species. Things almost always settle down without anybody going extinct. In the 1920's Elodea canadensis got introduced to Great Britain, and for a while it looked like it was going to crowd everything out. Now it is actually not that common a plant in rivers. Possibly something tasted it and found it good. Starlings got introduced into America about a century ago, and spread rapidly across the continent. Populations of bluebirds and red-headed woodpeckers declined drastically because the aggressive starlings out-competed them for nest holes. Now, bluebird and red-headed woodpecker populations have risen, perhaps not quite to their original levels, but they are definitely not appearing endangered. Perhaps they have become more aggressive. Wolves and grizzlies have been reintroduced into Yellowstone Nat. Park, and the moose mothers had to learn that these guys were dangerous. After losing their calves, they appear to have taken rather effective measures to protect their young the next year.

The zebra mussel is spreading with extraordinary rapidity throughout the great lakes and our river systems. It clears plankton out of the water so efficiently that it threatens other plankton feeding species. (I wonder if it would be useful in our tanks combating green water) We will just have to wait and see how it all works out. Actually, for aquatic plant fans, the zebra mussel is not all bad. Lake Erie and tributaries were so eutrophic that huge algae blooms shaded out submersed aquatics and Vallisneria was about to be declared a threatened species when along came the mussel and cleared everything up. Now, Vallisneria is doing so well that boats can hardly get through it. I'm kind of looking forward to seeing what happens when the zebra mussel makes it to the Ross Barnett reservoir. The water is too muddy now for much of anything to grow except floating plants. If the mussel can clear up the mud a bit, we might have a more interesting submersed flora.

Fire ants have been here in Mississippi for some time, and many local ant species have made somewhat of a comeback. Twenty years ago, fire ants used to invade my kitchen. Now it is the ubiquitous little brown sugar ant that will not be discouraged, no matter how many thousands of them I kill. They really run the place around my house. My whole front lawn is one vast sugar ant colony.

The killer bees are here. The brown tree snake is slithering northward from Florida. Climbing ferns are smothering trees. (I wonder if we could smother the climbing ferns if we planted lots of kudzu in the affected areas.) There are also monkeys in the trees as well as various exotic parrots. Walking catfish could have walked to Canada by now if they could take the cold weather. Hydrilla and Hygrophila polysperma are in a number of southern river systems. Even Glossostigma is loose. Is it going to be a lawn weed in damp areas? Maybe you could one-up the neighbors if you had an all-glosso lawn. I mean your real lawn, not the one in your aquarium. Practically every kind of aquarium plant grown in Florida tropical fish farms is already loose in Florida.

House finches were taken from their western habitat and introduced into the east around 1940. They have spread over most of the eastern U.S. and have already reached their western range. They are carrying with them a nasty eye disease that is frequently fatal. What can we do about it? Nothing. We will just have to let natural selection take its course. We have more immediate things to worry about, like West Nile disease and SARS.

Out of all the introduced species, the worst one is probably chestnut blight. That one really does appear to be capable of making the American chestnut extinct. Without scientific intervention, it probably will.

In the long run, everything will work out.
Paul Krombholz in sunny central Mississippi