The Washington Post has an interesting article today, Plastic junk brought invasive species to U.S. after Japan’s 2011 tsunami
The JTMDs ( Japanese tsunami marine debris) ferried a lot of animals, as the scientists described in a paper published Thursday in the journal Science. During six years of study, from June 2012 to February, Carlton and his colleagues counted more than 280 species of Japanese hitchhikers on 600 pieces of debris. Most were spineless marine critters: sea stars, sea slugs, oysters, barnacles, mussels, amphipods, bryozoa and isopods. Only a few alien arrivals, two species of Japanese fish, had backbones.
This phenomenon is not new.
Transoceanic crossings have happened for millions of years. A recent genetic study of trapdoor spiders found that they must have crossed on a raft from Africa to Australia a few million years ago; the spider relatives on each continent were too closely related to have last shared an ancestor when Africa and Australia were still geologically connected, some 100 million years back.
But what took scientist by surprise was the number of species that survived the voyage, and one of the reason they survived was because of man made stuff that floats and does not get water logged, stuff that has small cleavages that can support colonies for years.
But the JTMDs were mostly synthetics: fiberglass, polystyrene, polyvinyl chloride, material that stayed afloat and wouldn't degrade. Wood carried away by the tsunami probably sank, waterlogged or bored with holes by sea creatures.
We have changed the world with our synthetic materials. Once such rafts carried only small colonies of invasive life to distance shores. Now the invasion is much larger and the floating rafts can survive much longer.
The scientists also compared the age of North American marine life on the debris to the Japanese life. The uniquely American species were much younger than Japanese animals. Of the North American marine species “there were no adults, nothing like that,” Carlton said, just larvae one or two days old.
The debris at sea becomes like “traveling villages,” Fraser said. “Many rafting organisms brood their young — so their kids grow up on the same raft.”