You probably have at least a decent understanding of ecology, wetkarma, so I won't go into detail about the interconnectedness of life on Earth and how an invasive species can have effects on a local environment that cannot be predicted. We know, however, that the effects are almost always negative when put in terms of the overall health of the local ecology; that is to say that extirpations and extinctions are almost always a result.

As an appeal to your economic side, I'll offer an excerpt from biologist E.O. Wilson's book The Future of Life in which he explores the question, 'why should we care?'

Is there any way now to measure even approximately what is being lost? Any attempt is almost certain to produce an underestimate, but let me start anyway with macroeconomics. In 1997, an international team of economists and environmental scientists put a dollar amount on all the ecosystems services provided to humanity free of charge by the living natural environment. Drawing from multiple databases, they estimated the contribution to be $33 trillion or more each year. This amount is nearly twice the 1997 combined gross national product (GNP) of all the countries in the world--$18 trillion. Ecosystems services are defined as the flow of materials, energy, and information from the biosphere that support human existence. They include the regulation of the atmosphere and climate; the purification and retention of fresh water; the formation and enrichment of the soil; nutrient cycling; the detoxification and recirculation of waste; the pollination of crops; and the production of lumber, fodder, and biomass fuel.

The 1997 megaestimate can be expressed in another, even more cogent, manner. If humanity were to try to replace the free services of the natural economy with substitutes of its own manufacture, the global GNP would have to be increased by at least $33 trillion. The exercise, however, cannot be performed except as a thought experiment. To supplant natural ecosystems entirely, even mostly, is an economic--and even physical--impossibility, and we would certainly die if we tried. The reason, ecological economists explain, is that the marginal value, defined as the rate of change in the value of ecosystems services relative to the rate of decline in the availability of these services, rises sharply with every increment in the decline. If taken too far, the rise will outpace human capacity to sustain the needed services by combined natural and artificial means. Hence, a much greater dependence on artificial means--in other words, environmental prostheses--puts at risk not just the biosphere but humanity itself.

I've had this thought before. Sometimes I wonder how hard we'd work to save the dinosaurs if they were still around.

Some animals are a detriment to the natural world, and spread solely because of human selfishness (ie., the Egyptian wildcat-cum-housecat-cum-feral stray). Some animals are just able to get around on their own, or migrate simply because they need to (due to environmental changes). Some of the animals we fear will harm nature, simply don't survive out in nature (the domestic ferret, for instance).

- derumi (del-me)
"It is the farewell kiss, you dog!" - Muntadhar al-Zaidi

The history of invasive species that have been introduced by humans is overwhelmingly one of massive destruction and economic loss.  The Gypsy moth was brought to North America deliberately by some fool who thought, incorrectly, that he could develop a silk industry using the moth cocoons.  Now there are billions of dollars of damage done to trees every year in North America by Gypsy moths.  The zebra mussel was introduced into the Great Lakes (through sheer carelessness) and now cloggs up intake pipes throughout the region, causing vast problems and expense.  And there are thousands of other examples.  Generally speaking, biological change turns out to cost us money.  It's a very practical matter.

I think it's because of how unpredictable the ultimate consequences can be.  Environmentalists, I think, fear that we could do damage that we can't exactly predict by making large-scale changes to the environment.

And the thing is, they're right.  With the right stimulus, we could cause a chain reaction that could ultimately screw us.  This is why I think we can't go based on the idea that life adapts; life as a whole will, but we may not.  There's no real way to predict what will cause what, so shouldn't we try to play it safe when the consequences of a screw-up could be the extinction of our species?

So, for example, global warming: I think there's enough evidence there to say there's a good chance that it's true, but even without that, you'd be hard-pressed to convince me that dumping that much of anything into the atmosphere is not going to make changes to the environment.  Since we can't predict what those changes may be, it seems worth it to me to err on the side of caution.

Then, of course, there're those things we know are bad.  You don't have to be an environmentalist (in the general way that's used) to conclude that dumping highly toxic chemicals into ground water supplies is a bad idea and not worth the money you save on disposal.

Q: What do you think of western civilization? Gandhi: I think it would be a good idea.

"Declining biodiversity is never good, for biodiversity is a resource."

Tell that to our mammalian predecessors, who benefited greatly from the demise of the dinosaurs.

Declining biodiversity is never good, for biodiversity is a resource. Especially if a species died out before being thoroughly studied, it probably can't be recreated, and takes all its secrets to the grave.

Of course, anyone who's paid attention to what Darwin wrote realizes that "declining biodiversity" is a temporary phase. Given sufficient time and localized environmental pressures, species will evolve to fit the open ecological niches left in the wake of the decline.

That's Mark Sanford's love hemorrhoid, recently excised and flushed down a toilet.

Apparently it's a love hemorrhoid that just won't die.

Bryozoans! No, you fool, clumps of annelid worms! You must be kidding, surely you can see that Space Aliens have made themselves at home in Raleigh!

I can see why they chose Raleigh, what with its relative economic strength. Gorman Seedling may have been right, though. In these hard economic times, America can't be expected to provide jobs for everybody in this galaxy. What can that pulsating blob do that Americans can't do just as well?