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21 May 2001
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Mischievous Species Capitalize on GlobalizationBy Barry JamesInternational Herald TribunePARIS - Invading "aliens" are costing the global economy possibly hundreds of billions of dollars every year as well as spreading diseases and causing massive ecological destruction, yet no one is doing much about it. Environmental scientists say this invasion is among the costliest but least understood aspects of globalization. If this were an invasion from space, governments would be alarmed. But these are not extraterrestrials. They are ordinary animals, plants and insects that have escaped from their normal environment to wreak havoc someplace else. * A poisonous brown tree snake from Australia and Indonesia has exterminated most of the native forest birds on Guam and is spreading across the Pacific, sometimes by hopping a ride in the wheel well of an aircraft. *The Indian mongoose was introduced to the West Indies to control rats, but it has wiped out many native species of birds, reptiles and amphibians. It also carries rabies. * Crazy ants, proliferating in Asia, are indirectly destroying the rain forest on Christmas Island by exterminating land crabs that play an important role in the ecosystem. In one 18-month period, the ants were estimated to have killed three million crabs. Globalisation is dramatically increasing the opportunities for plants and animals to get from where they form a normal part of the flora and fauna to other places where they can become destructive pest, weeds and parasites, either because people deliberately introduce new species such as exotic fish and plants, or because the invaders slip aboard aircraft, ships and containers. And just ahead are trsngenic species, such as oversizes salmon, that some scientists warn could elbow out their cousins. The World Conservation Union in Gland, Switzerland, says awareness of the problems caused by invasive alien species is "alarmingly low," and is seeking to shine some light on a problem it says has "devastating consequences for the planet." The union, which brings together 78 states and some 10,000 scientists, is using World Biodiversity Day on May 22 to draw the attention of governments and the public to the threat posed to native species and ecosystems by biological invasion. "The emphasis will be on how to cope with with this alien invasion, not from Mars but from our planet," said Jeffrey McNeely, the organization's chief scientist. He said in an interview that economic losses caused by alien invaders probably costs several hundred billions of dollars every year, in addition to the irreparable loss of thousands of native species. "It is not just a problem for the wolrd's ecology, but it is closely linked with global trade and public health," he said arguing that species invasion should be more carfully considered under world trade rules. The harm caused byalien spcies is "externalized" in considerations of the costs of global trade, he said. Because the line of responsibility is insufficiently clear to bring about the necessary changes in behavior, the general public or future generations have to pay the bill. In a new book, "The Great Reshuffling," Mr. McNeely says that the impact of traade on biodiversity remains poorly addressed. For centuries, native species developed behind oceans and mountains but the modern explosion of travel and trade coupled with weakening customs and quarantine controls means that alien invasion is reaching epic proportions. About 20 percent of the species in the United States are considered invasive and harmful. They have been introduced either deliberately for economic gain, or inadvertently, such as zebra mussels let loose in the Great Lakes via ship ballast water, Asian tiger mosquitos brought in through used tire imports and Chinese longhorn beetles that hopped a ride in the timber of shipping pallets or containers and are threatening North American forests. In turn, China imported grass from the United States for golf courses, which is spreading like wildfire. The invaders don't just move in. They often entirely take over environments and proliferate at an alarming rate because they they are bigger or more aggressive than than the local species and find no predators to keep their numbers under control. Mr. McNeely cited the foot and mouth disease in Britain as an example of an alien invasion, in which an Asian virus finding no no natural defenses was able to propagate at an alarming rate. Mr. McNeely warned that global warming would increase health dangers from alien invaders. Already doctors are turning up cases of malaria and other tropical diseases in the vicinity of airports in countries where these do not not normally exist. These are some other examples: * Caulerpa seeweed, believed to have been dumped from the tanks of the Monaco aquarium, has proliferated throughout the northern Mediterranean and poses a serious threat to marine life. * Anm ornamental tree from South America called Miconia, planted in a botanical garden in Tahiti in the 1930s, now covers much of the island, deplacing native trees and contributing to a serious problem of landslides and soil erosion. * The South American water hyacinth, which is known to double in as little as 12 days, has invaded at least 50 countries, killing off fish and limiting boat traffic. A current debate in the United States over introducing the Asian black carp characterizes the debate between economic interests and the broader but less defined interests of the community and the environment. Fish farmers want to introduce the black carp to control a parasite called yellow grub that is spread by mollusks and infects commercially reared catfish, bass and bluegill. The black carp, which grow to more than a meter (39 inches) in length, live on mollusks. But environmentalists fear that the black carp will escape and gobble up mollusks in the Mississippi and other rivers, depriving native species of their food supply. Already, other species of carp that were introduced for weed control and then escaped and proliferated in the Mississippi have muscled out many of the local fish. What happened in Lake Victoria in Africa should be a warning. Fishermen introduced the Nile perch into the lake in the 1950s to counteract a drop in native species caused by overfishing. Since then the voracious perch has eliminated more than 200 local species, half of them unique to the lake, by preying on them and competing for food. The perch's flesh is oily, meaning that more trees have had to be cut down to fuel fires to dry the catch. The ensuing runoff of soil into the lake increased nutrient levels and allowed algea and water hyacinth to proliferate. This depleted the oxygen level in the water and killed off more fish. The result has been catastrophic not only for the environment but for the communities that used to make their living from the lake, according to the World Conservation Union. The example is a typical case of weighing the economic interests of the few against broader environmental concerns, an argument that scientists say the public interest usually loses. "It is true that great economic benefits a year in export income are flowing to a few people from the introduction of the perch, but none of the money is being spent on managing the considerable economic and ecological cost imposed on the poor or on the Lake Victoria ecosystem," Mr. McNeely said. Often people can't see the danger. Italy had to abandon aproject to exterminate the North American gray squirrel because people think of the rodent as cuddly, even though it is an agricultural pest and has driven the European red squirrel to near extinction. The ordinary house cat also ranks among the most predatory of the invaders, according to Peter Jackson, a retired expert on felines. "This is not often taken into account," he said. Not only can cats quickly recert to the wild, where they become formidable hunters and killers, but domestic pets cause enormous depredations during their nocturnal ramblings. Judging from a survey by the Mammal Society in Britain, cts could be killing more than 250 million birds and other creatures in the United Kingdom every year. The society says the toll be significantly reduced if owners kept their cats indoors at night or put a loud bell on their collar. Many aliens eventually become naturalized, like potatoes and tomatoes. Others are creatures that Noah might wish he had never allowed onto the ark, such as the Rosy wolf snail, the crazy ant and the walking catfish. But their is one species, Mr. McNeely says, that is more invasive than all the others put together. It's called homo sapiens. Article transcribed from the New York Herald Tribune (Europe edition, Zürich), 21.5.2001, p. 1. ** This material is distributed for research and educational purposes only. ** email feedback to<welcome@ecoglobe.org.nz> - on-line feedback |
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21 May 2001
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