How the 2011 Japanese Tsunami and Earthquake Sparked an Algae Invasion in the Pacific Northwest

Environment

In 2011, a tsunami devastated entire towns along Japan's northern islands. Not long after, the tsunami sent an invasion of algae to the Pacific Northwest.

ByDrew MacFarlane•

November 6, 2018

Updated: November 6, 2018, 5:17 pm ESTPublished: November 6, 2018, 5:17 pm EST

In 2013, scientists inspected a dock that washed up in a remote stretch of beach in northern Washington two years after the 2011 Japanese tsunami.
(Washington Department of Fish and Wildlife)

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In March 2011, a massive magnitude 9.0 earthquake boomed off Japan's eastern coast, triggering a disastrous tsunami that devastated entire towns along the Pacific coastline of Japan's northern islands. Months later, portions of the 1.5 million tons of floating debris began to wash up on the shores of the Pacific Northwest.

Researchers found that the debris wasn't the only thing that made the journey thousands of miles onto the shores of the Northwest – dozens of algae species rode the debris, ending up in Oregon and Washington, according to a recent study in Phycologia.

After years of collecting, observing and classifying the species that made their way across the Pacific Ocean, researchers found most had come ashore in environments similar to the area they were released. And, if given the chance, a full-scale invasion wouldn't have been out of the question.

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From June 2012 to July 2016, 42 pieces of "heavily fouled" debris were collected containing 82 identified species and variety of marine algae.

A barnacle-covered boat with Japanese markings that washed up along Oregon's coast following the 2011 Japan tsunami.
(John Chapman/Oregon State University)

“We did not expect debris to arrive with hitch-hiking biota as we did not think the Japanese species would survive the cross-Pacific journey,” Gayle Hansen, lead author of the study and marine phycologist at Oregon State University, told Earther.

While the invasion risk was deemed high, it was because of the rapid and large-scale debris removal efforts that prevented most potential introductions, the study noted.

Species have been able to survive thousands of miles while afloat on debris, as previously noted in a study in the journal Nature. However, a later study mainly focused on the 2011 tsunami documented organisms driven across oceans by tsunamis – something that had rarely been observed.

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The 2017 study published in the journal Science found nearly 300 larger species, ranging from sea stars to sponges and fish, turned up alive in North America and Hawaii, most of which arrived on the remains of manmade structures.

An author of the 2017 study and fisheries expert at Oregon State University, John Chapman explained that environmental threats from introduced algae are "very likely underappreciated," and tsunamis are just one part of the problem.

Floods, hurricanes, mudslides and "pure human messiness" are generating floating debris that serve as ferries between continents, said Chapman.

"This has turned out to be one of the biggest, unplanned, natural experiments in marine biology, perhaps in history," Chapman stated in the 2017 tsunami rafting study.

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