Japan tsunami brought hundreds of aquatic species to US coast

The devastating 2011 Japanese tsunami brought nearly 300 species to the shores of Hawaii and the west coast of the US, new research has found.

At its tallest point, the tsunami towered 125 feet over Japan's Tohoku coast and swept millions of objects out to sea, from small pieces of plastic to fishing boats and docks.

These kinds of objects helped the species attached to them complete the transoceanic journey, said the study published in the journal Science.

"I didn't think that most of these coastal organisms could survive at sea for long periods of time," said Greg Ruiz, a co-author and marine biologist at the Smithsonian Environmental Research Center in Maryland.

"But in many ways they just haven't had much opportunity in the past. Now, plastic can combine with tsunami and storm events to create that opportunity on a large scale," Ruiz added.

The scientists began finding tsunami debris washing up in Hawaii and western North America in 2012, with living organisms still attached.

From 2012 to 2017, they continued to find debris, including buoys, crates, vessels and docks.

In total, they detected 289 living species on tsunami debris originating from Japan, and they suspect there are far more that escaped their notice.

While the arrivals have slowed down, they have not stopped. The researchers said they were still finding new species when the study period ended in 2017.

Molluscs such as mussels occurred most frequently of all invertebrate groups.

Worms, hydroids (sea anemone and jellyfish relatives), crustaceans and bryozoans that form branch-like underwater colonies were not far behind.

Nearly two-thirds of the species had never been seen on the west coast of the US, the study said.