A study by researchers from Newcastle University, the James Hutton Institute, and University of Aberdeen have found that amphipods, small scavengers who live in the depths of the Mariana and Kermadec trenches, over 6 miles deep and 4,400 miles apart, contain “extremely high levels of Persistent Organic Pollutants” stored in their fatty tissue.
Better known as POPs, these include chemical compounds like PCBs and PBDEs, which were banned in the 1970s. This means that these pollutants have been working their way down the food web and into the deepest parts of the ocean, where they build up in larger numbers in creatures that live there.
The researchers used deep-sea landers to bring up samples of creatures that live in the deepest levels of the trenches.
“The amphipods we sampled contained levels of contamination similar to that found in Suruga Bay, one of the most polluted industrial zones in the northwest Pacific,” said study lead author Dr. Alan Jamieson of Newcastle University.
The deepest parts of the ocean are in significant danger as pollutants, released into the environment through industrial accidents and discharges and leakages from landfills, sink to the bottom of the ocean. Whether in their raw form, like bits of plastic, or in the bodies of animals that have ingested those pollutants, they end up building up on the bottom. When scavengers eat such creatures, they gets larger doses of POPs than animals in shallower water did.
It’s safe to assume that POPs aren’t the only pollutants that have reached the deep oceans, and it’s obvious that human activity has an even greater impact than we’d hoped.
“This research shows that far from being remote, the deep ocean is highly connected to the surface waters,” Jamieson wrote. “We’re very good at taking an ‘out of sight, out of mind’ approach when it comes to the deep ocean, but we can’t afford to be complacent.”