The Great Pacific Invasion

When the big tsunami hit Japan in 2011, many objects were washed out to sea. This flotsam provided for a giant “rafting event.” A rafting event is when animals, plants, etc. float across an otherwise uncrossable body of water and end up alive on the other side. With this particular event, I don’t think very many terrestrial life forms crossed the Pacific, but a lot of littoral — shore dwelling and near shore — animals and plants did.

Even though the Pacific ocean is one big puddle and you would think that any organism anywhere in it could just go to any other part of the ocean, like in the movie Finding Nemo, that simply isn’t true, and many organisms, most, don’t migrate at all and don’t disperse that far.

This video gives an overview of the dispersal of Japanese marine life forms across the pacific.

One might assume that this sort of rafting event happens all the time, or at least, every century or so when there is a tsunami. Partly true. But the flotsam that flotsamized the Pacific this time around included a lot of stuff that did not, could not, rot, and had generally more chance of making it all the way before floating.

And, of course, this is all being studied by scientists because it is an amazing opportunity. From the abstract of a paper just out:

The 2011 East Japan earthquake generated a massive tsunami that launched an extraordinary transoceanic biological rafting event with no known historical precedent. We document 289 living Japanese coastal marine species from 16 phyla transported over 6 years on objects that traveled thousands of kilometers across the Pacific Ocean to the shores of North America and Hawai‘i. Most of this dispersal occurred on nonbiodegradable objects, resulting in the longest documented transoceanic survival and dispersal of coastal species by rafting. Expanding shoreline infrastructure has increased global sources of plastic materials available for biotic colonization and also interacts with climate change–induced storms of increasing severity to eject debris into the oceans. In turn, increased ocean rafting may intensify species invasions.

Carlton, James, et. al 2017. Tsunami-driven rafting: Transoceanic species dispersal and implications for marine biogeography. Science 357:6358(1402-2406)

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4 thoughts on “The Great Pacific Invasion

  1. Ships from Asia bring nonnatives to North America sometimes.

    Here in SF Bay, we have invasions of mitten crabs and spartina grass, for example, that push out everything else.

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