What Happens When Tsunami Wreckage Floats Across the Pacific and Lands in America?

The state of the universe.
Aug. 15 2013 12:02 PM

The Tiniest Tsunami Refugees

They came from Japan, clinging to wreckage. They made it to the U.S., only to be destroyed. They are crabs, sea stars, and kelp.

Japanese tsunami debris in Oregon
Misawa 1 dock, washed ashore at Agate Beach, Ore.

Photo courtesy Oregon Parks and Recreation Department via Reuters

In his 40 years as a marine biologist, John Chapman has seen a lot of stuff wash up on a lot of beaches. The dock that washed ashore on Agate Beach, Ore., in early June last year was the most interesting thing he’d come across in a while. For one thing, the 188-ton dock was well over 60 feet long, nearly 20 feet wide, and 7 feet tall. But it teemed with much smaller items, too, Chapman could see when he looked up close—barnacles, mussels, a thick brown fringe of algae that hid any number of things.

The next day, Chapman went back with a pair of colleagues from Oregon State University to sample the assemblage more rigorously. Someone found a plaque on the dock with Japanese writing. An official with the Japanese consulate in Portland soon confirmed that the dock was from Misawa, a fishing port on Honshu Island—one of four identical docks wrested from their moorings during the 2011 earthquake and tsunami and cast out to sea.

The proceedings now had a newer and grimmer urgency. The dock was not only a public safety hazard, but also a biological one. Chapman and his colleagues surveyed like mad, scraping off specimens, bagging them for later identification. After two hours they had more samples than they could possibly process. Oregon state officials asked what they should do with everything that was left. Chapman didn’t hesitate. Kill it, he told them. Kill it all.

No one knows exactly how much marine debris was generated by the tsunami that devastated northern Japan. The Japanese government’s estimate, which has more or less entered the official record, is that 5 million metric tons were washed into the sea. Of that, 70 percent is thought to have sunk near the Japanese coast; the remaining 30 percent—roughly 1.5 million metric tons—was slung by the powerful Kuroshio Current across the Pacific Ocean.

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“We knew the stuff was coming,” Chapman says, “but it showed up a lot sooner than we thought it would.” In April 2012 the Coast Guard fired upon and sank the ghost fishing vessel Ryou-Un Maru, drifting and derelict in the Gulf of Alaska. In Oregon the dock from Misawa, which Chapman would take to calling Misawa 1, had drifted more than 4,300 miles across the Pacific in just 451 days.

Its haste would be the first of several surprises. Chapman and his colleagues expected that the creatures attached to the dock would be ocean-going organisms that the structure had picked up on its journey through the open sea. But the dock also supported a host of species that could only be from Japan. “It’s hard to overstate how surprising that was,” Chapman says. Convention had it that maybe, at most, one or two of those species should have survived the harsh pelagic environment. But here was a community that was largely intact, with sponges and mussels and anemones and urchins, all of which were known to live only in nearshore environments. It wasn’t a matter of a few hardy individuals clinging to life, either: In some cases, Chapman could see two or more generations of an organism. More alarming still was that at least two species—a sea star and a type of kelp—were on an international watch list of the 100 worst invaders.

“We had a very substantial edifice of information which said that was not supposed to happen,” Chapman says. So it was with particular interest that he rushed up to Olympic National Park the following December, when another dock (Misawa 3) washed ashore after 570 days at sea. Would the community it supported be similar to that of the first dock?

Chapman would have to wait to find out. Unlike Misawa 1, Misawa 3 wasn’t parked on a nice flat beach. Instead, it was tucked in a cove, wedged on sharp rocks, access to it hazardous. For several days, while the seas were high, Chapman and park scientists could only watch as waves pounded the dock. When the group was finally able to reach it, large patches had been cleared, the biota beaten off by the surf. But still they saw to their surprise that the remaining community was made up of different species than Misawa 1’s.

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