Tsunami drives species 'army' across Pacific to US coast

Mussels, starfish and dozens of other creatures great and small travelled across the waters, often on pieces of plastic debris.

Researchers were surprised that so many survived the long crossing, with new species still washing up in 2017.

The study is published in the journal Science.

The powerful earthquake that shook north-eastern Japan in March 2011 triggered a huge tsunami that reached almost 39m in height on the Tōhoku coast of Honshu.

The towering waves washed hundreds of objects out to sea, ranging in size from tiny pieces of plastic to fishing boats and docks.

A year later, scientists began finding tsunami debris with living creatures still attached, washing up on the shores of Hawaii and the western US coast from Alaska down to California.

"Many hundreds of thousands of individuals were transported and arrived in North America and the Hawaiian islands - most of those species were never before on our radar as being transported across the ocean on marine debris," lead author Prof James Carlton, from Williams College and Mystic Seaport, told BBC News....

The research team has detected 289 different species so far. Mussels were the most common, but there were also crabs, clams, sea anemones and star fish.
So common were findings that new species were still being discovered even as the study drew to a close in 2017, six years after the tsunami.

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The key element that has made this possible according to all the scientists involved is the ubiquitous presence of plastic, fibre glass and other products that do not decompose. ...

"For aeons if a plant or animal was to raft across the oceans, their boat was literally dissolving underneath them. What we have done now is provide these species with rather permanent rafts; we have changed the nature of their boats."

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