For the first time, researchers have found microplastics in creatures that reside in the deepest parts of Earth’s oceans.
Researchers believe the discovery, outlined in a study published last month in the Royal Society Open Science journal, means that “it is highly likely there are no marine ecosystems left that are not impacted by plastic pollution.”
Study authors examined three species of amphipods – a shrimp-like crustacean – in six deep-sea trenches across the Pacific Ocean: the Mariana Trench, the Japan Trench, the Izu-Bonin Trench, the New Hebrides Trench, the Peru-Chile Trench and the Kermadec Trench. The locations, which were sampled between 2008 and 2017, ranged from roughly four to seven miles deep.
The study found that more than 80 percent of the organisms tested had plastic fibers and particles in their digestive systems. The deeper the crustaceans were found, the more likely they were to have ingested plastic. For example, at nearly seven miles deep in the Mariana Trench, 100 percent of the sampled creatures contained plastic.
The majority of plastics in the ocean are floating on the surface, but they start to fall as they break down. The deeper they sink, the less chance there is for currents to pick them up and disperse them. That means that ocean trenches collect a lot of plastic that has no where else to go.
“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, [the plastic] just sits there. It can’t flush and there are no animals going in and out of those trenches,” study author Alan Jamieson said in a statement.
Microplastics, small plastic pieces less than 5 millimeters long, are known to negatively affect about 700 marine species, according to the research.
What plastics do to ocean surface-dwelling species has been widely documented – from whales with stomachs full of plastic bags to a sea turtle with a plastic straw stuck in its nose – but what the debris could do to deep-sea species is not yet fully understood. Researchers speculate that they could block digestive tracts and limit mobility.
Microplastics can come from a variety of sources, including larger pieces of plastic, clothes and microbeads used in face washes.