A Japanese buoy covered with Crassostrea gigas, a type of oyster, found floating offshore in Alsea Bay, Oregon. Credit: James T. Carlton
When a magnitude 9 earthquake shook the western Pacific Ocean floor and sent a tsunami crashing into Japan in 2011, millions of pieces of debris — from docks and fishing boats to plastic pollution — were swept out to sea. Now, a new study finds that nearly 300 species hitchhiked aboard that debris across the Pacific and were scattered along the west coast of North America.
The findings, published in the journal Science, conclude that 268 species of macro- and micro-invertebrates, two fish species, and 19 species of microscopic organisms called protists made their way across the Pacific in what the scientists called a “megarafting” event. They included barnacles, mussels, limpets, the Japanese barred knifejaw fish, and Japanese shipworm. The study was led by marine scientist James Carlton of Williams College.
Species catching a ride on debris across oceans isn’t a new phenomenon. In fact, most scientists believe that is how islands were colonized by new flora and fauna. But previously this “rafting” happened aboard natural debris, things like fallen trees or kelp. Man-made objects, particularly plastics, last much longer, enabling species to travel farther than ever before. This increases the chance of foreign species reaching new ecosystems and spurring an invasive species takeover.
The study authors warn that because of climate change, sea level rise, and worsening, more frequent extreme weather events, there is likely to be more debris washing into our oceans from coastal communities. The result could be a surge in megarafting events and species movement.
Credit: Science
