Scientists have discovered microplastic hotspots on the ocean floor, formed by deep-sea currents that act as conveyor belts moving tiny plastic fragments around. One such hotspot, in the Tyrrhenian Sea, part of the Mediterranean Sea, had 1.9 million microplastic pieces on just one square meter, according to a new study published in the journal Science.
Public awareness of plastic pollution in the ocean has largely been driven by the discovery of floating masses of plastic, such as the Great Pacific Garbage Patch, which is roughly the size of Texas. But of the 10 million tons of plastic waste that enter the oceans each year, these floating patches account for just 1 percent. The other 99 percent is believed to reside in the deep ocean. Now, the discovery of these deep conveyor belts will help scientists better track and locate these underwater accumulations.
“Almost everybody has heard of the infamous ocean ‘garbage patches’ of floating plastic, but we were shocked at the high concentrations of microplastics we found in the deep-seafloor,” Ian Kane, a geologist at The University of Manchester and lead author of the new study, said in a statement. “We discovered that microplastics are not uniformly distributed across the study area; instead they are distributed by powerful seafloor currents which concentrate them in certain areas.”
Kane and his colleagues warn that these conveyor belts also transport nutrients and oxygenated water, meaning these deep-sea plastic hotspots form in the same locations as important ecosystems rich in marine life.
The research shows “how detailed studies of seafloor currents can help us to connect microplastic transport pathways in the deep-sea and find the ‘missing’ microplastics,” said Mike Clare, a marine scientist at the National Oceanography Center in the United Kingdom who co-led the research. “The results highlight the need for policy interventions to limit the future flow of plastics into natural environments and minimize impacts on ocean ecosystems.”