The world’s deepest ocean trenches are becoming “the ultimate sink” for plastic waste, according to a study that reveals contamination of animals even in these dark, remote regions of the planet.
For the first time, scientists found microplastic ingestion by organisms in the Mariana trench and five other areas with a depth of more than 6,000 metres, prompting them to conclude “it is highly likely there are no marine ecosystems left that are not impacted by plastic pollution”.
The paper, published in the Royal Society Open Science journal, highlights the threat posed by non-biodegradable substances in clothes, containers and packaging, which make their way from household bins via dump sites and rivers to the oceans, where they break up and sink to the floor.
“If you contaminate a river, it can be flushed clean. If you contaminate a coastline, it can be diluted by the tides. But, in the deepest point of the oceans, it just sits there. It can’t flush and there are no animals going in and out of those trenches.”
The effects on deep-sea species are as yet unclear, though scientists speculate they will experience the same problems of blocked digestive tracts and restricted mobility as creatures at higher depths. They may also be more vulnerable because the trenches are food-scarce ecosystems, which prompts scavengers and predators to gobble up anything they can find.