Story Photos
 Photo Photo courtesy of Robyn Draheim, Portland State University Researchers John Chapman, left, and Jeff Cordell sift through silt from Portland's Columbia Slogh as they search for invasive species such as Siberian prawns. Erik Hanson watches from the scientists' boat. |
Alien invaders: 81 non-native species lurk in Columbia
Friday, November 5, 2004 11:17 PM PST
By Eric Apalategui
Printable version
E-mail this articleYou could pluck a New Zealand mudsnail out of a pristine mountain stream, pass it through a fish's digestive tract, dump it into the salty Columbia River estuary -- and it might not only survive the journey, it could clone itself into a colony of billions.
The snails are among the most worrisome of 81 invasive species documented in a new report that found that more than one in five -- and maybe even a majority -- of the animals and plants that live in the Columbia today don't belong in the river.
Moreover, the rate of invasions has quickened so that in the past decade a new non-native species is discovered every five months.
Though they often slip in unnoticed aboard foreign ships or by other means, invasive species pose serious environmental and economic consequences. Environmentalists seek tighter controls to protect the river's native species from such "biological pollution."
The scientists completed the Lower Columbia River Aquatic Nonindigenous Species Survey (LCRANS) for the U.S. Coast Guard and U.S. Fish and Wildlife Service. The federal agencies, which paid $275,000 for the study, regulate many of the human activities that spread unwanted species and manage the river's native animals and plants. The federal government recently agreed to pay for a similar survey of the middle reaches of the Columbia and the lower Snake River.
In the lower Columbia River study, scientists from Portland State University, University of Washington and Oregon State University gathered 54 invasive species during field work. They added another 27 species to the report that are well-known in the lower river, including many introduced fish. They finished the three-year study last month but haven't publicly announced its completion.
Eight of the species the researchers found had never been scientifically documented in the river, including an aquatic worm that was unknown on the West Coast before researchers found it in the Columbia.
"We know very little about what any of these species' negative impact could be," said Robyn Draheim, a research assistant at PSU's Center for Lakes and Reservoirs and coordinator of the LCRANS project. "There are a lot of questions we don't know how to answer at this point in time."
For example, those mudsnails only grow to about the size of the word "the" in this sentence, but they have infested parts the Columbia River estuary so thickly that 400,000 can inhabit a square meter. Scientists don't yet know how the mudsnails or most invasive species might disrupt the river's environment, but they fear the consequences.
"That's a number that makes you think something has to be happening," Draheim said.
Nina Bell, executive director of Northwest Environmental Advocates, said so little is known about the river's invasive species because little study has been done. "It's fairly widely acknowledged that if you don't spend any money looking for them, you won't find them," she said.
Researchers agreed.
"It's shocking how little we know" about invasive species in the Columbia River, said OSU researcher John Chapman. He was a principal investigator for the LCRANS study, which is the most comprehensive study of the problem to date but barely begins to answer such questions. "We're confident that we know very little about these problems. We're struggling with that."
"The 'kill 'em off' approach might be out of our range," Chapman said. "What we're trying to do is manage things, so we need to know what our options are --- and we don't (know)."
Another principal investigator, UW researcher Jeff Cordell, has been looking at the Columbia River's zooplankton --- tiny animals near the bottom of the food chain --- for two decades now.
In the early 1990s, one species of invasive copepod ruled the river's estuary, an area that may not have had its own native species of these tiny crustaceans. But a decade later, Cordell found two new Asian species dominated the population of lower river copepods. How such microscopic power struggles play out for the river's environment, no one really knows, Cordell said.
Other Columbia River invaders include the Siberian prawn, a freshwater shrimp thriving in sloughs near Portland that might compete with juvenile salmon for food; the purple varnish clam that poses a risk to shellfish growers in coastal bays; tiny oligochaetes (worms) that may harbor deadly fish diseases; and the Chinese mystery snail, a silver-dollar-sized critter that aquarium keepers apparently released with unknown consequences.
Non-native animals and plants often out-compete or prey upon native species or destroy habitats. They also can disrupt fishing, farming, shipping, water pumping, and so on --- costing the United States $122 billion a year, according to a Cornell University ecologist.
The invaders often are more successful than natives because they often arrive without diseases and predators that keep them in balance in their natural habitats.
Scientists believe there could be far more invaders awaiting discovery or identification. While 34 percent of 269 aquatic species the researchers could identify are natives and 21 percent are known invaders, the rest have unknown origins. The found an additional 55 organisms that could neither be identified nor ruled out as possible invaders.
Some LCRANS researchers and environmentalists advocate stricter rules for ballast water to control new invasions. Bell said that current rules have too many loopholes, and her group is suing the U.S. Environmental Protection Agency to force stronger national standards.
"We as a society should have already learned the hazard from this general problem from experiences in places like the Great Lakes," Bell said, referring to the Midwest's costly invasion of zebra mussels. "It's pretty astounding how slowly we are dealing with it. It's just foolhardy."
Scott McEwen, aquatic ecologist and director of technical programs for Lower Columbia River Estuary Partnership, another environmental group, said zebra mussels and other examples of "biological pollution" can be more troublesome than chemical contaminants.
Pollution from a factory or a sewer pipe can be stopped at the source, McEwen said. "With invasive species, it's a completely different thing. Once they're here, they are very difficult to eradicate."
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