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.

"We know extinctions occur with invasions," said John Chapman, assistant professor of fisheries and invasive species specialist at Oregon State University's Hatfield Marine Science Center. "This is like arrows shot into the dark. Some of them could hit a mark."

Though the global economy has accelerated the process in recent decades by the sheer volume of ships, most from Asia, 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, hotspots like 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. Kelps and tiny shrimp-like creatures change the food web that fish, marine mammals and even humans depend on.

A 2004 study in the scientific journal Ecological Economics estimated 400 threatened and endangered species in the U.S. are facing extinction because of pressures from invasive species.

It is too early for scientists to know how much Japanese tsunami debris may add to the invasive species already here.

"It may only introduce one thing," said Cohen of the Aquatic Bioinvasions research center. "But if that thing turns out to be a big problem, we would rather it not happen. There could be an economic impact, an ecological impact, or even a human health impact."

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, said Carlton.

"That's the `Johnny Clamseed' approach," he said, referring to Johnny Appleseed, the pioneer apple tree planter of the early 19th century. "While that is theoretical, we don't actually know if that kind of thing happens."

One thing they know is that the bigger the debris, the more likely it has something on it.

Chapman estimated there were hundreds of millions of individual living organisms on the dock when it washed up on Agate Beach outside Newport, Ore.

But even a small plastic float that washed up on a beach in Alaska carried a live oyster, said Mandy Lindeberg, research scientist at the NOAA Fisheries Auke Bay Laboratories in Juneau, Alaska.

The smaller bits of plastic expected to make up most of the tsunami debris won't have anything except species they picked up at sea, said Carlton.

On the dock, about half the plant species already exist on the West Coast, said Gayle Hansen, a research marine taxonomist at Oregon State University, who has spent hours with her eye scrunched up against a microscope examining samples from the dock.

Among the exotic seaweeds was one known as wakame, which has become a nuisance around the world, but is not yet found in Oregon, she said.

Whether hitchhiking species will survive here depends on randomness, she said. Seaweeds probably would not have survived to reproduce in the crashing surf at Agate Beach. It's the wrong kind of environment. But if they had floated into Yaquina Bay, very similar to their home waters in Japan, they could grow and reproduce.

Lindeberg said, "The only defense for invasive species is early detection. Just like cancer."

While monitoring is relatively cheap, say $30,000 to watch nearby waters for species from the dock, trying to stop an established invasion is expensive. California spent $7 million trying to eradicate a seaweed, she said.

She said she hoped there would be funding for monitoring tsunami invasive species.

James Morris, a marine ecologist and invasive species specialist at the NOAA National Centers for Coastal Ocean Science, in Beaufort, N.C., said the idea a natural disaster like the tsunami could introduce a new avenue for invasive species is intriguing.

"It goes to show you that when it comes to invasive species, there are some things you can work to regulate and control," he said. "And there are issues like this that come up that open up a whole different realm of possibilities."

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  • This June 7, 2012 photo provided by the Oregon Department of Parks and Recreation shows a seaweed from Japan commonly known as wakame on a dock that floated up on Agate Beach near Newport, Ore., after being torn loose from a fishiing port in Japan by the 2011 tsunami. Scientists are concerned that some of the tsunami debris coming to the West Coast and Alaska could spread invasive species like this seaweed. (AP Photo/Oregon Parks and Recreation Department, ho)

  • This June 7, 2012 photo proivded by the Oregon Department of Parks and Recreation shows an unidentified person sterilizing the side of a dock float torn loose from a Japanese fishing port by the 2011 tsunami that washed up on Agate Beach near Newport, Ore. Scientists say they don't now yet how much the tons of tsunami debris may add to the invasive species problem on the West Coast. (AP Photo/Oregon Department of Parks and Recreation)

  • This June 6, 2012 photo shows Sue Odierno, of Salishan, Ore., looking at the massive dock from Japan that washed ashore on Agate Beach near Newport, Ore. Scientists are concerned that tsunami debris like this could be a new avenue for invasive species arriving on the West Coast (AP Photo/Rick Bowmer)

  • This photo, taken by the Oregon Park and Recreations Department Thursday, June 7, 2012, shows exotic mussels attached to a dock float that washed up on Agate Beach Tuesday near Newport, Ore. State authorities are considering how to dispose of the millions of marine creatures that hitchhiked across the Pacific Ocean aboard the dock float torn loose from a Japanese fishing port by the 2011 tsunami so they will not compound the problem of invasive species.(AP Photo/Oregon Parks and Recreation Department, ho)

  • This photo, taken by the Oregon Park and Recreations Department Thursday, June 7, 2012, shows an exotic mussel attached to a dock float that washed up on Agate Beach Tuesday near Newport, Ore. State authorities are considering how to dispose of the millions of marine creatures that hitchhiked across the Pacific Ocean aboard the dock float torn loose from a Japanese fishing port by the 2011 tsunami so they will not compound the problem of invasive species.(AP Photo/Oregon Parks and Recreation Department, ho)

  • This photo, taken by the Oregon Park and Recreations Department Thursday, June 7, 2012, shows an exotic pink Japanese acorn barnacle attached to a dock float that washed up on Agate Beach Tuesday near Newport, Ore. State authorities are considering how to dispose of the millions of marine creatures that hitchhiked across the Pacific Ocean aboard the dock float torn loose from a Japanese fishing port by the 2011 tsunami so they will not compound the problem of invasive species.(AP Photo/Oregon Parks and Recreation Department, ho)



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  • This photo taken Wednesday, June 6, 2012 and supplied by the Oregon Department of Parks and Recreation, shows a large dock that washed ashore early Tuesday on Agate Beach, a mile north of Newport, Ore. The nearly 70-foot-long dock was torn loose from a fishing port in northern Japan by last year's tsunami and drifted across thousands of miles of Pacific Ocean, a Japanese Consulate official said Wednesday.(AP Photo/Oregon Parks and Recreation)

  • This photo taken Wednesday, June 6, 2012 and supplied by the Oregon Department of Parks and Recreation, shows the metal plaque from a large dock that washed ashore early Tuesday on Agate Beach, a mile north of Newport, Ore. The nearly 70-foot-long dock was torn loose from a fishing port in northern Japan by last year's tsunami and drifted across thousands of miles of Pacific Ocean, a Japanese Consulate official said Wednesday.(AP Photo/Oregon Parks and Recreation)

  • A man looks at the massive dock with Japanese lettering that washed ashore on Agate Beach Wednesday, June 6, 2012, in Newport, Ore. A nearly 70-foot-long dock that floated ashore on an Oregon beach was torn loose from a fishing port in northern Japan by last year's tsunami and drifted across thousands of miles of Pacific Ocean, a Japanese Consulate official said Wednesday. (AP Photo/Rick Bowmer)

  • People walk along the beach as waves pound the massive dock that washed ashore on Agate Beach Wednesday, June 6, 2012, in Newport, Ore. A nearly 70-foot-long dock that floated ashore on an Oregon beach was torn loose from a fishing port in northern Japan by last year's tsunami and drifted across thousands of miles of Pacific Ocean, a Japanese Consulate official said Wednesday. (AP Photo/Rick Bowmer)

  • Massive dock, potentially tsunami debris, hits Oregon Coast

    Fisheries scientists Dr. John Chapman (with bucket), and Dr. Jessica Miller climb aboard the beached dock at Agate Beach on Wednesday, June 6, 2012 a mile north of Newport, Ore. Evidence is mounting that the nearly 70-foot floating dock that washed ashore came from an area of Japan devastated by last year's tsunami. (AP Photo/The Oregonian, Thomas Boyd) MAGS OUT; TV OUT; LOCAL TV OUT; LOCAL INTERNET OUT; THE MERCURY OUT; WILLAMETTE WEEK OUT; PAMPLIN MEDIA GROUP OUT

  • The surf pounds against the massive dock that washed ashore on Agate Beach Wednesday, June 6, 2012, in Newport, Ore. A nearly 70-foot-long dock that floated ashore on an Oregon beach was torn loose from a fishing port in northern Japan by last year's tsunami and drifted across thousands of miles of Pacific Ocean, a Japanese Consulate official said Wednesday. (AP Photo/Rick Bowmer)

  • The surf pounds against the massive dock that washed ashore on Agate Beach as Sue Odierno, of Salishan, walks pass Wednesday, June 6, 2012, in Newport, Ore. A nearly 70-foot-long dock that floated ashore on an Oregon beach was torn loose from a fishing port in northern Japan by last year's tsunami and drifted across thousands of miles of Pacific Ocean, a Japanese Consulate official said Wednesday. (AP Photo/Rick Bowmer)

  • This photo taken Wednesday, June 6, 2012 and supplied by the Oregon Department of Parks and Recreation, shows a large dock that washed ashore early Tuesday on Agate Beach, a mile north of Newport, Ore. The nearly 70-foot-long dock was torn loose from a fishing port in northern Japan by last year's tsunami and drifted across thousands of miles of Pacific Ocean, a Japanese Consulate official said Wednesday.(AP Photo/Oregon Parks and Recreation)

  • Massive dock, potentially tsunami debris, hits Oregon Coast

    Scientists from OSU and BLM agents inspect a massive dock with Japanese lettering that washed ashore on Agate Beach on Wednesday, June 6, 2012 a mile north of Newport, Ore. Evidence is mounting that the nearly 70-foot floating dock that washed ashore came from an area of Japan devastated by last year's tsunami. (AP Photo/The Oregonian, Thomas Boyd) MAGS OUT; TV OUT; LOCAL TV OUT; LOCAL INTERNET OUT; THE MERCURY OUT; WILLAMETTE WEEK OUT; PAMPLIN MEDIA GROUP OUT

  • Massive dock, potentially tsunami debris, hits Oregon Coast

    Scientists from OSU and BLM agents inspect a massive dock with Japanese lettering that washed ashore on Agate Beach on Wednesday, June 6, 2012 a mile north of Newport, Ore. Evidence is mounting that the nearly 70-foot floating dock that washed ashore came from an area of Japan devastated by last year's tsunami. (AP Photo/The Oregonian, Thomas Boyd) MAGS OUT; TV OUT; LOCAL TV OUT; LOCAL INTERNET OUT; THE MERCURY OUT; WILLAMETTE WEEK OUT; PAMPLIN MEDIA GROUP OUT

  • A large dock is washed ashore off Newport, Oregon's Agate Beach on Tuesday, June 5, 2012. State parks officials say a metal plate with Japanese writing has been found attached to the dock, raising speculation it might be debris from last year's tsunami in Japan. Oregon parks spokesman Chris Havel said Wednesday a photo of the plate was emailed to the Japanese consulate in Seattle for review. (AP Photo/The Oregonian, Lori Tobias) MAGS OUT; NO SALES; TV OUT; LOCAL TV OUT; LOCAL INTERNET OUT; THE MERCURY OUT; WILLAMETTE WEEK OUT; PAMPLIN MEDIA GROUP OUT