Synthetic fibers found at bottom of Mariana Trench

map of trenches
CC BY 4.0 A.J. Jamieson et al. – Locations of the six trenches around the Pacific rim where amphipods were sampled for microplastic ingestion.

Removed from the stomachs of tiny creatures, these plastic particles are a dismal indicator of just how widespread plastic pollution is.

Plastic particles have been found in the guts of tiny animals living at the bottom of the Mariana Trench. This trench is the deepest point on Earth, and the discovery that plastic has invaded even here has led scientists to conclude that there is likely "no marine ecosystems left that are not impacted by plastic pollution."

In a study just published by the Royal Society Open Science journal, researchers explain how they baited, caught, and dissected deep-sea creatures from six locations of more than 6,000 meters (3.7 miles) in depth – the Peru-Chile trench in the southeast Pacific, the New Hebrides and Kermadec trenches in the southwest Pacific, and the Japan trench, Izu-Bonin trench and Mariana trench in the northwest Pacific.

The creatures studied were amphipods, crustaceans related to shrimp and crabs that scavenge on the seabed. The researchers found that 72 percent of the total samples contained plastic fibers and fragments in their guts. From the Atlantic's writeup:

"In the least polluted of these sites, half of the amphipods had swallowed at least one piece of plastic. In the 6.8-mile-deep Mariana Trench, the lowest point in any ocean, all of the specimens had plastic in their gut."

This might seem counterintuitive; shouldn't the deepest point be the most pristine? This, however, is not the case. When contaminants enter a deep marine trench, they cannot escape. There is no place to flush out, to move along. Instead they settle on the seabed to be consumed by amphipods that, living in such a hostile environment, cannot afford to be picky about what they eat.

Alan Jamieson, a marine biologist from Newcastle University who led this research, describes amphipods as exceptional scavengers whose dietary choices have a lasting effect on the entire food chain.

"Since they sit at the bottom of the trench food webs, their catholic appetite can doom entire ecosystems. 'They're like bags of peanuts,' Jamieson says. 'Everything else eats amphipods — shrimp, fish — and they’ll end up consuming plastics, too. And when the fish die, they get consumed by amphipods, and it goes round and round in circles.'"

The presence of plastic particles is concerning because these can attract PCBs and other toxins. They can leach chemicals of their own, depending on what they're made of. (In this case, lyocell, rayon, ramie, polyvinyl and polyethylene.) The physical presence of particles in a tiny creature's belly creates disruptions, blocking its digestive tract and impeding mobility. The pieces found were also relatively enormous.

“The worst example I saw was a purple fiber, a few millimeters long, tied in a figure-of-eight in an animal no longer than a centimeter,” Jamieson says. “Imagine if you swallowed a meter of polypropylene rope.”

Jamieson said they've discovered species that have never been seen in an uncontaminated state. "We have no baseline to measure them against. There is no data about them in their pristine state. The more you think about it, the more depressing it is." (via the Guardian)

Synthetic fibers found at bottom of Mariana Trench
Removed from the stomachs of tiny creatures, these plastic particles are a dismal indicator of just how widespread plastic pollution is.

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