PARIS - Animals in the deepest ocean trenches have been found with plastic fragments in their gut, according to new research showing how pollution reaches even the bowels of the planet.
More than 300 million tons of plastics are produced annually, and there are at least 5 trillion pieces of plastic floating in our oceans.
Because deep-sea exploration is expensive and time-consuming, most studies on plastic pollution until now had been close to the surface, showing widespread plastic contamination in fish, turtles, whales and sea birds.
Now British researchers have discovered cases of plastic ingestion among tiny shrimp in six of the deepest ocean trenches.
In the Mariana Trench, east of the Philippines — the deepest depression on Earth — 100 percent of the animals studied had plastic fibers in their digestive tracts.
“Half of me was expecting to find something, but that is huge,” said Alan Jamieson, from Newcastle University’s School of Natural and Environmental Sciences.
Jamieson and his team normally spend their time looking for new species in the depths of the oceans. But they realized that over the course of expeditions dating back a decade they had accumulated dozens of specimens of a species of tiny shrimp that lives between 6,000 and 11,000 meters (19,500 to 36,000 feet) beneath the surface.
They decided to look for plastic.
“We are sitting on the deepest data set in the world, so if we find (plastics) in these, we are done,” Jamieson said.
The team was astonished by just how widespread the plastic contamination at extreme depths proved to be.
For instance, the Peru-Chile Trench in the southeast Pacific is around 15,000 kilometers (9,300 miles) from the Japan Trench. Yet plastic was found in both.
“It’s off Japan, off New Zealand, off Peru — and each trench is phenomenally deep,” Jamieson said.
“The salient point is that they are consistently found in animals all around the Pacific at extraordinary depths, so let’s not waste time. It’s everywhere.”
Of the 90 individual creatures the team dissected, 65 — over 72 percent — contained at least one plastic microparticle.
The study, published in the journal Royal Society Open Science, said it was unclear if the particles had been ingested at higher depths by fish that then died and sank.
But when the team analyzed the fibers — most of which appeared to be clothes fabrics such as nylon — they found that the plastics’ atomic bonds had shifted compared to new material, suggesting they were several years old.
Microplastic particles are either dumped directly into the seas via sewers and rivers or are the product of the breakdown of larger chunks of plastic over time.
Once they start gathering bacteria, they get heavier and eventually sink.
“So even if not a single fiber were to enter the sea from this point forward, everything that’s in the sea now is going to eventually sink, and once it’s in the deep sea, where is the mechanism to get it back?” asked Jamieson. “We are piling all our crap into the place we know least about.”
Because plastic contamination is now so widespread, even at extreme depths, the team cautioned that it is nearly impossible to know what effect plastic ingestion is having on bottom-dwelling species.
“These particles could just pass straight through the animal, but in the animals we looked at they must be blocking them. The equivalent would be for you to swallow a 2-meter polypropylene rope and expect that not to have an adverse affect on your health,” said Jamieson.
“There’s no good aspect to this.”