Huge plastic islands, also known as garbage vortices, float in the world’s oceans: tens of thousands of tons of plastic waste, which in the North Pacific, for example, is moved in circles for years by large ocean currents until it drifts to the coast or sinks into the deep sea. A work by Linsey Haram of the Smithsonian Environmental Research Center in Edgewater and her team in Nature Communications showsthat this flotsam is not only colonized by animals, but that it even opens up completely new habitats for actual coastal dwellers.
Scientists first became aware of this phenomenon in 2011 when, after the strong earthquake in Japan and the ensuing tsunami, huge amounts of waste were washed into the sea, some of which landed on the American west coast after years. More than 300 species from the east side of the Pacific made their way to the other side of the ocean. Haram’s working group therefore took a closer look at the Pacific garbage whirlpool.
She worked with the Ocean Voyages Institute, which has set itself the goal of fishing some of the garbage out of the sea and recycling or disposing of it on land. During one trip, the crew collected 103 tons of garbage, some of which went to Haram and Co for analysis. The group identified and counted the animals that had colonized the waste. In doing so, they came across numerous species of Hydrozoa, anemones and amphipods, which actually occur near the coast – although these were not just isolated cases, but also colonies that were able to reproduce. So the animals weren’t just random victims; they actively conquered a new habitat.
“The open ocean was previously not habitable for coastal organisms,” says Greg Ruiz of the Marine Invasions Lab: “Partly because of the limitations of the habitat – there used to be no plastic there – and partly, we thought, because it is a food desert. “The study shows that this is not the case. However, it is not yet known why. The garbage may keep drifting through areas that are more biologically productive. Or the plastics act like an artificial reef, which in turn creates food sources or attracts corresponding organisms.