How Did Japanese Species End Up in US Waters?

While the USA is pretty strict when it comes to border control, some suspects are just impossible to keep tabs on. Following Japan's devastating 2011 tsunami an "army" of invasive species has been swept across the Pacific and into US waters. It could spell big problems for local ecosystems, with scientists warning that hundreds of Japanese marine species have already been identified on American coastline.

An invasion of "incomparable scale"

While storms are continually brewing in the Pacific, this particular assault was triggered by Japan's deadly Tohoku tsunami back in 2011. Often hitching a ride on pieces of plastic debris, the tsunami swept mussels, starfish and dozens of other creatures thousands of miles into US waters. Researchers were surprised that so many of the marine "hitchhikers" survived such a long and perilous crossing.

"There's nothing comparable in the scale of what we've seen before in the history of marine science," observes lead author Professor James Carlton.

Marine hitchhikers a big concern for Stateside ecosystems

The study was published in the journal Science, and was triggered when debris began to wash up on the shores of Hawaii and the western US coast one year after an earthquake shook Japan's Pacific coast. In its wake the magnitude 9.0 – 9.1 undersea megathrust earthquake triggered a towering tsunami that reached a height of almost 39 metres.

"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," explains Carlton.

To date the study has identified 289 different species, though Carlton and his colleagues are expecting to continue to make new findings. While no invasive colonies have yet been established, Carlton is concerned that it's only a matter of time.

"Much of the debris is still out there and it could be that some of these Japanese species will still arrive. I wouldn't be surprised if a small Japanese fishing boat lost in 2011 was to show up 10 years after the event."

Plastic supports transoceanic voyages

One of the most interesting questions raised is how the organisms were able to survive for such a long period of time. According to co-author John Chapman, a key factor is the presence of plastic, fibre glass and other products that do not decompose in water.

"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," he says.

Undertaking integrated ocean research and technology development, groups like the UK's National Oceanography Centre (NOC) play a critical role in monitoring global ocean health, from the coast to the deep sea. For a closer look at their work don't miss 'Ocean-Going Lab...The Real Test of a Nutrient Analyser.'