Study: 2011 tsunami swept species from Japan to Oregon - with help from plastic debris

Non-biodegradable items from the 2011 Japanese earthquake and tsunami that were found by Oregon State University researchers along the coast of Oregon. (OSU)

NEWPORT, Ore. – The 2011 earthquake and tsunami in Japan swept boats, motorcycles, docks and countless other bits of debris out to sea - with some hitchhikers on board.

A new study by Oregon State University marine scientists suggests pastics in the ocean may help these non-native species reach foreign shores.

The study, co-authored by OSU researchers John Chapman and Jessica Miller, appeared in the journal Science this week.

"Between 2012 and 2017, scientists documented nearly 300 species of marine animals arriving alive in North America and Hawaii on hundreds of vessels, buoys, crates, and many other objects released into the ocean by the Japanese earthquake and tsunami of March 2011," Oregon State's Mark Floyd writes in a new article for OSU News & Communications. "Unexpected was that coastal species from Japan would not only survive the trip through the hostile environment of the open North Pacific Ocean, but continue to survive for many years -- four or more years longer than any previous observations of species found living on what are called 'ocean rafts'."

Tsunami debris with living species from Japan have washed up in North America and Hawaii as recently as spring of this year, Floyd reports.

Plastic captured the attention of researchers, especially as compared to wood.

"Between 2012 and 2014, wood from homes and other buildings in Japan landed in Oregon and other locations bearing Japanese species that included dense populations of wood burrowing marine clams known as shipworms. Shipworms destroy wood. Wood landings declined dramatically after 2014," Floyd writes. "The declining wood landings early in the study brought the researchers' attention to the fact that it was the non-biodegradable debris -- plastics, fiberglass, and styrofoam -- that was permitting the long-term survival and transport of non-native species."

That may come into play in the future after tsunamis, floods or hurricanes along developed coastal areas, the researchers suggest.

“Given that more than 10 million tons of plastic waste from nearly 200 countries can enter the ocean every year – an amount predicted to increase by an order of magnitude by 2025 – and given that hurricanes and typhoons that could sweep large amounts of debris into the oceans are predicted to increase due to global climate change, there is huge potential for the amount of marine debris in the oceans to increase significantly,” said James Carlton, an internationally known invasive species expert with the Maritime Studies Program of Williams College and Mystic Seaport, the lead author on the study.

Chapman said none of the Japanese species that have made the trip via tsunami debris have become established on the West Coast - that scientists know of.

But he said it can take time for species to establish a new population and come to the attention of biologists.

“One thing this event has taught us is that some of these organisms can be extraordinarily resilient,” he said. “When we first saw species from Japan arriving in Oregon, we were shocked. We never thought they could live that long, under such harsh conditions. It would not surprise me if there were species from Japan that are out there living along the Oregon coast. In fact, it would surprise me if there weren’t.”

Miller, an OSU marine ecologist who also works at the university’s Hatfield Marine Science Center in Newport, Oregon, said “not only were new species still being detected on tsunami debris in 2017 but nearly 20 percent of the species that arrived were capable of reproduction. We were able to not only identify this unique suite of species but, in some cases, examine their growth and ability to reproduce which provides useful information on how they fared during their transoceanic voyage.”

Plastics appear likely to have played a role in helping species make the voyage.

“These vast quantities of non-biodegradable debris, potentially acting as novel ocean transport vectors, are of increasing concern," Carlton said, "given the vast economic cost and environmental impacts documented from the proliferation of marine invasive species around the world."

That finding might never have come to light save for the March 2011 disaster.

“This has turned out to be," Chapman said, "one of the biggest, unplanned, natural experiments in marine biology, perhaps in history.”

The research was funded by the Ministry of the Environment of Japan through the North Pacific Marine Science Organization, the U.S. National Science Foundation, and Oregon Sea Grant.

Among the other authors of the study are Nancy C. Treneman, Oregon Institute of Marine Biology; and Brian P. Steves and Gregory M. Ruiz, Smithsonian Environmental Research Center and Portland State University.

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