Tsunami aftermath: animals traveled to america on plastic floats
The devastating tsunami in japan in 2011 sent countless creatures on plastic mud floats across the pacific toward america. For many years afterward, researchers continued to find trumpet parts with animals and algae originally from japan on the coasts of north america and hawaii.
They arrived alive in the new world and some of them had even reproduced on the way, the researchers write in the journal "science". In the future, more and more creatures are likely to be spread in this way – because more and more plastic debris is floating in the oceans and because more frequent and stronger storms are expected in view of climate change.
A seaquake off the coast of japan caused a tsunami in march 2011 that devastated large parts of the coastline. Millions of objects – from small pieces of plastic to entire ships and parts of port facilities – were spooled into the pacific ocean.
The team led by james carlton of williams college began in 2012 to examine fragments and wreckage that had washed up from japan on the pacific coast of north america and the coasts of hawaii. By the time they reached the US coast, they had traveled at least 7000 kilometers on the open sea.
By 2017, researchers had analyzed a total of 634 objects and the animal species that traveled on them. They found at least 289 species that had survived the voyage alive – and for up to six years after the tsunami. They included fish, mussels, snails, worms, crabs and algae. Quite a few of the traveling populations had multiplied along the way.
The findings show how resilient some species are, says john chapman, one of the scientists involved from oregon state university. "When we saw species from japan for the first time, we were shocked. We never thought they would live so long in these harsh conditions."
Whether some species have already settled permanently in their new home is currently unclear. "I wouldn't be surprised," says chapman. "Frankly, i would be surprised if they didn't do it."It could take years or decades to actually prove the presence of alien species.
Researchers expect such sea voyages on plastic parts to become more common in the future. Up to ten million tons of plastic debris enter the world's oceans every year – and the amount is expected to increase in the coming years. This would create a whole new way of species dispersal. Wood fragments from japan, on the other hand, were found by the researchers in their analyses only up to the year 2014, after which the proportion declined rapidly. Wood decomposes in the ocean, is destroyed by shipworms or sinks to the bottom.
The transport of organisms on natural floats such as trees and kelp has contributed to the colonization of islands and the exchange of species between continents, writes steven chown of monash university in melbourne in a commentary on the study. In recent years, plastic parts have become increasingly important: they have had a longer life span and could therefore continue to demand their freight.