Scientists have found plastic in the stomachs of animals living more than 10 kilometres below the ocean surface in the deepest places on Earth. Researchers led by Newcastle University in the UK have uncovered evidence that not only have plastics now reached the deepest chasms of our oceans but they are being ingested by the animals that live there.
They tested samples of crustaceans found in the ultra-deep trenches that span the entire Pacific Ocean – the Mariana, Japan, Izu-Bonin, Peru-Chile, New Hebrides and Kermadec trenches. These range from seven to over 10 kilometres deep, including the deepest point, Challenger Deep in the Mariana Trench, at a staggering 10,890 metres deep.
The team examined 90 individual animals and found ingestion of plastic ranged from 50 per cent in the New Hebrides Trench to 100 per cent at the bottom of the Mariana Trench. The fragments identified include semi-synthetic cellulosic fibres, such as Rayon, Lyocell and Ramie, which are all microfibres used in products such as textiles, to Nylon, polyethylene, polyamide, or unidentified polyvinyls closely resembling polyvinyl alcohol or polyvinylchloride – PVA and PVC.
“The results were both immediate and startling,” said Alan Jamieson from Newcastle University. “This type of work requires a great deal of contamination control but there were instances where the fibres could actually be seen in the stomach contents as they were being removed,” sad Jamieson. Using deep-sea ‘landers’ developed by Jamieson, the technology free-falls to the ocean floor and carries out a variety of monitoring and sampling tasks.
There is now an established appreciation of plastic pollution in our oceans and the detrimental effects this has on marine organisms, researchers said. An estimated 300 million tonnes of plastic now litters the oceans, with more than five trillion plastic pieces weighing over 250,000 tonnes currently floating on the surface. Although the majority of marine litter can be observed floating on the surface, the degradation and fragmentation of plastics will ultimately result in sinking to the underlying deep-sea habitats, where opportunities for dispersal become ever more limited.
“This study has shown that manmade microfibres are culminating and accumulating in an ecosystem inhabited by species we poorly understand, cannot observe experimentally and have failed to obtain baseline data for prior to contamination,” said Jamieson. “These observations are the deepest possible record of microplastic occurrence and ingestion, indicating it is highly likely there are no marine ecosystems left that are not impacted by anthropogenic debris,” he said.