Invasive species ride tsunami debris to US

Associated Press

When a floating dock the size of a boxcar washed up on a sandy beach in Oregon, beachcombers got excited because it was the largest piece of debris from last year’s tsunami in Japan to show up on the West Coast.

But scientists worried it represented a whole new way for invasive species of seaweed, crabs and other marine organisms to break the Earth’s natural barriers and further muck up the West Coast’s marine environments. And more invasive species could be hitching rides on tsunami debris expected to arrive in the weeks and months to come.

Though the global economy has accelerated the process in recent decades by the sheer volume of ships entering West Coast ports, the marine invasion has been in full swing since 1869, when the transcontinental railroad brought the first shipment of East Coast oysters packed in seaweed and mud to San Francisco, said Andrew Cohen, director of the Center for Research on Aquatic Bioinvasions in Richmond, Calif. For nearly a century before then, ships sailing up the coast carried barnacles and seaweeds.

Now, hot spots such as San Francisco Bay amount to a “global zoo” of invasive species, and perhaps 500 plants and animals from foreign shores have established in U.S. marine waters, said James Carlton, professor of marine sciences at Williams College. They come mostly from ship hulls and the water ships take on as ballast but also get dumped into bays from home aquariums.

The costs quickly mount into the untold billions of dollars. Mitten crabs from China eat baby Dungeness crabs that are one of the region’s top commercial fisheries. Spartina, a ropey seaweed from Europe, chokes commercial oyster beds. Shellfish plug the cooling water intakes of power plants.

The dock, torn loose from a fishing port on the northern tip of Japan, was covered with 1.5 tons of seaweed, mussels, barnacles and even a few starfish. Volunteers scraped it all off, buried it above the high water line, and sterilized the top and sides of the dock with torches.

But there was no telling whether they might already have released spores or larvae that could establish a foothold in a bay or estuary as it floated along the coast, Carlton said.