ROBERT SIEGEL, HOST:
From NPR News, this is ALL THINGS CONSIDERED. I'm Robert Siegel.
AUDIE CORNISH, HOST:
And I'm Audie Cornish. A bizarre event has drawn scientists to a beach in Oregon. A floating concrete dock has washed ashore. It had been ripped from its moorings in Japan by last year's tsunami. To the amazement of scientists, the dock is encrusted with mussels, barnacles and other marine life from Asia that somehow survived.
But as NPR's Christopher Joyce reports, experts are also worried some of these organisms could become pests in U.S. waters.
CHRISTOPHER JOYCE, BYLINE: Marine biologist John Chapman heard about the dock last Tuesday. It hit the beach a few miles from his laboratory at Oregon State University. When he saw it, he was shocked.
JOHN CHAPMAN: There were just an amazing diversity of species that we have never seen before. And the massiveness of this thing, it's about 100 tons of stuff. And it really does have millions of organisms and maybe hundreds of species.
JOYCE: The dock was 66 feet long, 19 feet wide and seven feet high; a plaque with a name on it revealed its source: a coastal town in Japan.
Chapman expected the organisms stuck to the dock would be deep sea species that hopped aboard during its Pacific transit. Japanese coastal creatures could not have survived a 14-month trip in the open ocean. But when he looked closer, he realized he was wrong.
CHAPMAN: You know, it's appalling to me that this artificial island of Asian species was ripped off of their shore and transplanted to here really intact and that we would not have predicted that. So what we thought we knew is wrong.
JOYCE: Chapman says nothing like this has ever happened on such a large scale. The dock was like a Noah's ark for all these local Japanese species, or perhaps like a Trojan horse.
CHAPMAN: There could be very bad things in there. We already know of very bad disasters of introduced species.
JOYCE: In Oregon, there's the invasive oyster drill, a worm that threatens the oyster business. Chapman says non-native species are regular arrivals on the Oregon coast, but this one is different.
CHAPMAN: It's as if we had this turnstile that would only let through one a year, and then, you know, a stampede came.
JOYCE: In just two days of examining the dock, scientists have found a starfish that looks like one that has overwhelmed huge coastal areas in Australia; and there's a nasty species of brown algae all over it. Jessica Miller is an Oregon State University biologist at the site. She says workers are trying to get rid of what they can.
JESSICA MILLER: The state hatched a plan, which included this morning going out with a team to scrape as much of it as it could and bag up as much as they could and dragging it up the beach to reduce the risk that it might drift and float and settle somewhere local.
JOYCE: Unfortunately, whatever was growing on the bottom of the dock isn't there anymore.
CHAPMAN: When it got up on the beach, there was nothing left. It all got ground off, which means that all of that was washed off in the ocean. It got away.
JOYCE: University scientists are still trying to census this floating menagerie. But Miller says the team is also mindful of the event that brought it to Oregon.
MILLER: A gentleman came up and put some white flowers in a crevice on the float, really reminding us that, yes, it's interesting scientifically, but it's really only here because of a really serious, devastating human tragedy.
JOYCE: Christopher Joyce, NPR News.
NPR transcripts are created on a rush deadline by Verb8tm, Inc., an NPR contractor, and produced using a proprietary transcription process developed with NPR. This text may not be in its final form and may be updated or revised in the future. Accuracy and availability may vary. The authoritative record of NPR’s programming is the audio record.