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CHICAGO - Our planet is threatened by another high-stakes environmental problem linked to human activities, an Oregon State University researcher warned today (March 28) at an international meeting.

Call it, "global swarming."

Throughout the world, non-native plants and animals that range in size from "viruses to water buffalo" are driving out native life forms, wildlife ecologist Bruce Coblentz told scientists assembled in Chicago for the North American Wildlife and Natural Resources Conference.

We haven't yet comprehended the magnitude of the problem, said the OSU researcher, who has studied the impact of non-native creatures much of his career in places such as Aldabra Atoll in the Indian Ocean, the Galapagos Archipelago off the coast of Ecuador and islands off the southern California coast.

In a presentation titled "Biological Invasions: Global Swarming is Heating Up," Coblentz said that "every successful species invasion is analogous to an explosion. An invasion is the shock wave that radiates out from the point of detonation, and each invading species proceeds at its own rate."

Native species often become "living debts" for an invasion, he said. Their eventual extinction, no matter how hard humans try to counteract it, is the price that will be paid within the natural system.

"And we don't even know what the full price is," he added. "In other words, successful biological invasions are going to cause extinctions, but we don't necessarily know when, or whose."

He discussed the spread of non-native European starlings from Central Park in New York City to Alaska in only a little more than 60 years, and Sika deer expanding their range more gradually, but steadily, on the eastern shore of Maryland.

"Homogenization of biotas (the plants, animals and microorganisms of regions) worldwide and the extinction events almost certain to occur as a result will surely shape the course of future organic evolution," the researcher told scientists attending the conference. "The end result, to be played out over the next few million years, is that we are diminishing the options," he added. "Rather than proceeding with a rich diversity of organisms, many of which have evolved to specifically exploit certain unique conditions and environments, future evolution will involve a more limited diversity of organisms that share a single trait of being able to succeed in a human-dominated landscape."

Pretty much every environment in the world already has been disturbed by humans, the researcher emphasized. Also, human transportation systems now allow organisms place-bound for eons to leapfrog oceans and other natural barriers, sometimes as crops, livestock or pets, and sometimes as stowaways.

Biological invasions are expensive to human societies in several ways, Coblentz said, pointing to lost crop production, disease, lost production of desirable native species and physical damage to natural ecosystems and human property.

"Dollar estimates for damages associated with invasive species in the United States alone are staggering," he said. "For example, the Office of Technology Assessment estimated a minimum cost associated with 79 invasive species in the United States to be at least $97 billion for the 85-year period 1906-1991." One researcher put the figure much higher, at more than $137 billion per year, he noted.

How can humans combat the problem more effectively?

"The rate of spread ... is important in determining how quickly and how intensively control measures must be instituted to be effective against an invasive species," Coblentz said. "In fact, the time factor may be the key to beginning to think responsibly about invasions."

"Those (invasions) that occur too slowly to be noticed by our temporal frame of reference may not elicit any reaction by ecologists or natural resource managers," he said. "Nevertheless, they may still be tremendously rapid by measures of ecological time. A seeming non-problem could really be a major problem, but humans are too short-lived to perceive it."

It is ironic that humans would attempt to stem the tide of biological invasions, the researcher noted.

"... Homo sapiens have probably been the most invasive species in the history of the planet," he said. "In comparison with rates of reproduction and dispersal by which we sometimes judge invasibility, humans are quite inferior, yet the outcome of our global invasion from its origin in tropical Africa has been absolute."

The researcher spoke of "bleak" possibilities in the 21st century, in terms of extinction of native creatures.

"On the other hand," he said, "we still have most of our biota and habitats that can be preserved, and the time to assure their preservation has already arrived."