Marine plastic enabling coastal species to cross oceans
Plastic waste is enabling communities of coastal species to cross oceans, for the first time in recorded history, according to marine scientists. Almost 300 species from Japan reached North America alive between 2012 and 2017, after travelling on plastic objects such as crates which entered the pacific after the Japanese earthquake and tsunami in 2011. Whilst this disaster was an extreme example of such transit, scientists believe that storm surges are causing many non-native species to travel on “rafts” of marine plastic aided by storm surges. Mollusks, bryozoans, crustaceans and worms were the species most likely to have survived transit.
When the massive tsunami waves of the 2011 eastern Japan earthquake rolled back out to sea, they pulled with them fragments of docks, boats, and buoys that sometimes contained living stowaways. These hitchhikers—including crustaceans, mollusks, and fish—rode debris "rafts" through ocean currents over thousands of kilometers before finally washing ashore on Hawaiian and North American coastlines, sometimes years later. Now, researchers who studied hundreds of Japanese marine species living in and on this tsunami debris conclude that they were witnessing a "transoceanic biological rafting event with no known historical precedent," they report today in Science . The scientists studied more than 600 pieces of tsunami-ejected debris—mostly nonbiodegradable fiberglass and polystyrene foam—that had swept up along Hawaiian, U.S. mainland, and Canadian shores. They counted nearly 300 Japanese species colonizing the debris, including roughly 80 different species on the largest piece, a 170-ton section of dock. In many cases, the scientists found that the animals had successfully reproduced along their journey. That's evidence that the relatively slow movement of the debris (2-4 kilometers per hour) helped species adapt to changing conditions across the Pacific Ocean, the team wrote. But life hitching a ride between continents might have a dark side, the researchers noted: Debris could transport invasive species, forever changing ecosystems.