PSU Magazine Winter 2004

Closer to home, Chinese mitten crabs have swarmed into San Francisco Bay. The Asian crustacean, first discov– ered in the bay about 10 years ago, burrows into and weakens dikes and levees, is host to oriental lung fluke (a human parasite), and aquarium studies show it enjoys feasting on steelhead eggs. Now Portland State researchers are studying the damage wreaked by the nation's array of alien invaders and wondering, "ls the Northwest next?" A two-year study of the lower Columbia River by PSU's Center for Lakes and Reservoirs found a total of 292 aquatic species, and of that num– ber, 20 percent were not native. One section of the Columbia is so badly infested with New Zealand mud snails that they've not only completely crowded out native snails, but they're also changed the feeding patterns for some threatened fish. "You dig up a shovelful of sedi– ment," says Mark Sytsma, associate professor and center director, "and it's all New Zealand mud snail. Hundreds of thousands per square meter. And they're also in lakes and streams along the Oregon coast." A ,ross the nation, nonindigc– nous plants and animals cause more than $137 billion worth of damage annually. By some estimates, these alien invaders threaten more than 40 percent of endangered plants and animals. In Oregon, non-native walleye in the Columbia River feast on salmon eggs. European green crabs in Coos Bay gorge on young native Dungeness crabs. And overall, more than 130 non-native aquatic species infest the state's 100,000 miles of rivers and 6,200 lakes. How do they get here? Plants and creatures can hitchhike on the hulls of recreational boats. They can be deliberately introduced, as in the case of nutria, the South American rodent brought to the U.S. to provide furs for the fashion industry. But a major source of inadvertent aquatic introduction stems from the shipping industry. After unloading cargo, sailors stabi– lize their ships by pumping aboard harbor water that includes small aquatic creatures and plants. At the next port, the ship discharges the bal– last water and takes on its cargo. The problem is that along with the water, the ship discharges the creatures and plants picked up in the previous port. A large vessel can require as much as 5 million gallons of ballast water. In all, about 21 billion gallons of ballast water a year are discharged from ships reaching U.S. ports. As ships travel between continents and even along a coast, they spread creatures throughout the world. Local efforts to address the problem began several years ago when represen– tatives from the Center for Lakes and Reservoirs , Port of Portland, and Port of Astoria formed the Columbia River Aquatic Nuisance Species Initiative (CRANSI) with the support of U.S. Sen. Ron Wyden. The group's first task was to establish a baseline of non– native creatures and plants currently in the Columbia. CRANSI's study of the Columbia River below Bonneville Dam discov– ered 68 non-natives in a total of about 300 species reported in the river. "Every time we go out and collect samples," says Sytsma, "it seems we find a new species ... They're slipping in under our radar." With the baseline study completed in late 2003 , the next step is to figure out a way to combat the invaders. One of the simplest ways to thwan foreign species arriving by boat is to .