Shopping Cart
RSS FeedGlobal Economy Spreading Destructive Species: The Invisible Threat of Bioinvasion
by Worldwatch Institute on October 10, 1998
Global Economy Spreading Destructive Species: The Invisible Threat of Bioinvasion
HOLD FOR RELEASE
06:00 PM EDT
Saturday, October 10, 1998
by Chris Bright
Biological pollution is sweeping the planet, as the global trade carries non-native "exotic" species across all boundaries, the Worldwatch Institute announced today. Bioinvasion--the spread of exotic species--has become the second greatest threat to biological diversity.
"Because it brings the intelligence of evolution to bear, bioinvasion is a kind of 'smart' pollution," said Chris Bright, author of Life Out of Bounds: Bioinvasion in a Borderless World. "Compared to living things, chemical spills are 'dumb'--they're inert, they cannot reproduce and they tend to dissipate over time. But when an exotic species establishes a beachhead, it can proliferate over time and spread to new areas. It can also adapt--it tends to get better and better at exploiting an area's resources, and at suppressing native species."
Natural boundaries like mountains, deserts, and ocean currents used to isolate one ecosystem from another. But trade, travel, and other human activities are moving more and more organisms around these boundaries, touching off more and more invasions, says the study, which was funded by the Foundation for Ecology and Development (now the Deep Ecology Foundation).
Some invading species have made a name for themselves-the pipe-clogging zebra mussel, the bird-devouring brown tree snake, or the landscape-smothering kudzu vine. But the public has not yet grasped the full dimensions of this threat. "People often know about a few really troublesome exotics," said Bright. "But they tend to see them simply as accidents. What they don't seem to realize is that these invasions are part of a pattern. This is happening all the time, virtually everywhere, and the rate at which it's happening appears to be growing."
Even among policymakers, exotics rarely get effective attention, according to Bright, a researcher and editor at the Institute. "Many scientists and land managers are deeply concerned about this issue," said Bright, "but it's proving extremely difficult to translate that concern into coherent policy. Thus far, attempts to deal with the problem in an integrated way have been pretty weak and inconsistent."
There are, however, some encouraging signs. In the United States, for example, the Clinton administration is now working on a strategy to coordinate the efforts of the more than 30 federal agencies that are trying to cope with exotics. "This could be a very positive development," said Bright. "But because both the invaders themselves and the processes that spread them are so deeply entrenched, it's important that any new strategy be designed for the long haul."
A bioinvasion occurs when a plant or animal is released into a new environment and finds conditions to its liking. (See the attached "Panorama Invasion" sheet for more examples.) If the exotic encounters no effective competitors, predators, or diseases in its new range, it may undergo a population explosion. In the process, it may out-compete native species for some essential resource. Or if it's a microbe, it may infect them; if a predator, it may simply eat them.
The study shows how these processes have led to the suppression of native species all over the world, and sometimes to their extinction. According to Bright, exotics can now be found in most of the Earth's lake and river systems, along most coastlines, on virtually all major islands, and scattered throughout all of the continents including Antarctica.
Invasion itself is an ancient process, Bright said. "What's new is that the integration of the global economy is spreading more and more creatures around-in ship ballast water, in containers, even in commodities themselves." This "biopollution," combined with intentional releases of certain exotics (aquaculture fish, garden plants, pulpwood trees, and so on) is pushing invasion rates far beyond their natural background levels.
"It's not just large industries that are setting off invasions," said Bright. "Even tiny industries, like the hobby aquarium industry are having an enormous impact. In the United States, most exotic fish that are entirely foreign to the U.S. have been introduced by hobbyists and breeders."
In some areas, particularly islands, current rates of invasion may be more than 1 million times their natural levels. "No ecosystem can stand up to that kind of pressure indefinitely," said Bright, who regards current invasion rates as no more sustainable over the long term than current rates of deforestation or greenhouse gas emissions. "Bioinvasion is becoming a new measure of the unsustainability within the current economic order."
High rates of biotic mixing are a social menace too, in several ways. In 1991, for example, epidemic cholera returned to the Americas, probably via contaminated ship ballast water released into a Peruvian harbor. More than 1 million people were infected and some 10,000 died; the cost to South American countries came to more than $200 billion in emergency drinking water and sewer repairs alone. The risk of such epidemics is likely to grow, according to Life Out of Bounds, as most of humanity is pulled into a single microbial system.
Other invasions are destroying parts of the natural resources base. Crop viruses spread by an exotic species of whitefly have forced the abandonment of more than 1 million hectares of cropland in South America. An Atlantic jellyfish provoked the collapse of the fisheries in the Black Sea. The water hyacinth, a South American aquatic plant, has done the same thing in Africa's Lake Victoria. According to documents Bright obtained through a Freedom of Information Act request, the U.S. Defense Intelligence Agency has argued that failure to control the water hyacinth could lead to a major "humanitarian threat" that might destabilize the lakeside countries of Kenya, Uganda, and Tanzania.
The need to act is growing more acute, Bright said, for two reasons. First, unlike most other forms of environmental degradation, time does not heal invasions; established exotics generally continue to entrench themselves and spread. Second, there are many potential emergencies just waiting in the wings:
- Increasing travel between Kenya and India could bring yellow fever into India, where the population is wholly unvaccinated against it.
- In the U.S. Pacific Northwest, lumber company efforts to weaken regulations on raw log imports could, if successful, lead to the introduction of hundreds of new pest species into North American forests.
- In Southeast Asia, inadvertent introduction of Amazonian rubber pathogens could destroy most of the world's rubber production-and for certain applications, especially in medicine, there is no substitute for rubber.
Yet Bright argues that we are already in a position to make rapid progress against the invaders. In the book's final chapter, he makes the case for a counterinvasion strategy that includes:
- repairing loopholes and strengthening relevant international treaties like the International Plant Protection Convention;
- plugging the pathways through which exotics move, for instance by re-engineering ship ballast water systems;
- developing international monitoring systems and databases to overcome the fragmentation of information about invasive species;
- ending the introduction of exotic species by natural resource managers, as in the use of exotic forage plants on rangeland, or exotic grasses for soil conservation;
- developing ecological literacy in the population as a whole, so that people can see the value of native landscapes and will be less likely to tolerate invasions.
