Accessibility links

World: Trade Spawns 'Biological Pollution'

  • Bruce Keppel



Bellingham, Wash.; 1 May 1997 (RFE/RL) - About the time that the Berlin Wall came tumbling down, an event of a related yet much different nature -- and potentially as far-reaching -- was taking place half a world away on the West Coast of the United States. There, someone had discovered a green crab.

What distinguished such an outwardly ordinary happening in California was the fact that this species of crab doesn't live in North America. It is a native of Europe, where its voracious appetite for other shellfish is held in check by natural predators absent from the green crab's new home in the Pacific Ocean. It grows by destroying local species -- especially oysters, which have only recently made a comeback in the Pacific waters off the U.S. West Coast.

Just eight years after that initial find in San Francisco Bay, Associated Press this week reports the finding of mature green crabs in the port city of Coos Bay -- 1,000 kilometers to the north in Oregon, the state between California and Washington. These European natives now threaten Oregon's commercial oyster crop. And, because Coos Bay exports some of its harvest, there is a danger that shipments of local oysters may take with them to yet other regions tiny juvenile green crabs.

But the East to West odyssey of the green crab is no isolated incident in a global phenomenon known as "biological pollution" -- or the introduction of alien species into another ecosystem. The end of the Cold War, symbolized by the falling of the Berlin Wall in November 1989, has opened up to world trade huge areas long closed to the world beyond, and with it an increase in the potential for "biological pollution."

Nor is this pollution limited to oceanic species.

In just the last decade, the freshwater "zebra mussel," a small mollusk native of the Caspian Sea, has invaded the Great Lakes near Chicago and spread south to New Orleans and east to New York state, quickly becoming a dominant species at the expense of the natives -- and in one case causing the shutdown of an electrical generating plant near Detroit, Michigan.

A survey by "Smithsonian Magazine," published by the national museums in Washington, D.C., lists such other unwanted immigrants as an Asian crab; a European fish called the ruffe, now at home in the north-central state of Minnesota; the Japanese horn snail, now found along the Pacific Coast; and the European flat oyster, now a permanent resident of the north Atlantic Coast in Maine.

One of the most economically devastating of these biological imports is the Mediterranean fruit fly.

This tropical pest periodically arrives in sunny Southern California, usually as larvae hidden in tropical fruits. Once an outbreak erupts, the voracious eater devours that state's bountiful harvest of soft fruits -- to the extent that California has at times had to resort to spraying pesticide by helicopters to eradicate the pest before it becomes a permanent and costly resident of the nation's leading agricultural state.

If the fruit fly comes by air, biologists say most of the water species, like the green crab and the zebra mussel, come aboard sea-going freighters engaged in world trade.

That can happen when a ship takes on ballast water in the Caspian Sea, for example, and then crosses the Atlantic and releases its ballast (and all the microscopic Caspian species that were scooped up with the water) on arriving to take on cargo at one of the Great Lakes ports.

In the case of the green crab, Oregon's state legislators are urging the U.S. Congress to appropriate money to improve enforcement of a 1996 federal law setting ecologically sound standards for ship ballast water.

In short, an unwanted by-product of the forces creating a global economy -- marked by increased international trade -- is destruction of native species of sea life with no clear estimate of what this loss of diversity may mean for the future.

Already, according to the Nature Conservancy, a non-profit organization, about a third of North American fish species, two-thirds of shellfish species and three-quarters of freshwater mussel species are rare or threatened with extinction. One biologist has counted 139 alien aquatic-animal species established in the Great Lakes alone.

But, according to "Smithsonian": "Biological pollution is not just a North American problem: American comb jellies (jelly-fish-like organisms) threaten Black Sea fisheries, and toxic dinoflagellates, a kind of plankton, from our country have closed shell-fisheries in Tasmania, off Australia.

A sampling of ballast water contained in 159 Japanese freighters entering Coos Bay, Oregon, found 367 kinds of marine organisms. These included shrimps, crabs, fish, barnacles, sea urchins, starfish, worms, jellyfish, clams and snails. Concludes Smithsonian: "The immensity of the problem becomes apparent when you consider that 39,000 merchant ships sail the world's oceans."

The events set into motion since the fall of the Berlin Wall appear to have accelerated biological pollution by greatly expanding trade between parts of the world long closed to commerce because of the Cold War. That upswing has led to repeated attempts by the U.S. Congress since 1990 -- and as recently as last year -- to regulate use of ballast water in freighters calling at North American ports. One way has been to increase the salt content in the water to levels sufficient to kill any freshwater species on cargo ships entering the Great Lakes.

But that's not only expensive for the shippers but hard to enforce in practice.

Still, biologists praise the legal requirement as a first step toward protecting ecosystems. "Without such steps, the life-forms in our waterways and those around the world could become homogenized," says James Carlton of the University of North Carolina, "and dominated by a small group of very hardy and aggressive species."
XS
SM
MD
LG