Not even creatures living in some of the deepest waters in the world are free from the effects of toxic, man-made chemical pollution, according to a new study led by scientists from the UK and published Monday in the online-exclusive journal Nature Ecology and Evolution.
According to USA Today and the Washington Post, Dr. Alan Jamieson, a marine ecologist from Newcastle University, and his colleagues found elevated levels of industrial chemicals a group of tiny shrimp-like crustaceans living at depths of 10,000 meters in the Mariana Trench.
In fact, they discovered higher levels of polychlorinated biphenyls (PCBs) in amphipods in the Trench than in crabs living in waters fed by one of the most polluted rivers in China. They also found comparable levels of PCBs and other harmful chemicals in the bodies of similar creatures living in the slightly-less deep Kermadec Trench.
The study indicates that humans have left a “footprint in the deepest places in the world,” Jamieson told USA Today. “Not only are (the pollutants) in every single sample, regardless of species, depth, trench, whatever, the concentrations are extraordinarily high. That was a big surprise.”
“We still think of the deep ocean as being this remote and pristine realm, safe from human impact, but our research shows that, sadly, this could not be further from the truth,” he added in separate comments made to the Guardian. “The fact that we found such extraordinary levels of these pollutants really brings home the long-term, devastating impact that mankind is having on the planet.”
Contamination levels were ‘sky high,’ study authors found
As part of their research, Jamieson and colleagues from the University of Aberdeen and the James Hutton Institute used a robotic submarine to collect amphipods from the Mariana and the Kermadec Trenches and analyzed them for PCBs and polybrominated diphenyl ethers (PBDEs), two now-banned types of chemicals linked to a variety of health problems.
Both PCBs and PBDEs are persistent organic pollutants (POPs), industrial chemicals whose use has been limited or banned for years but which do not break down in the environment, according to the Guardian. Studies have linked these substances to neurological and immune problems, as well as to reproductive issues and even cancer in humans, the Washington Post added.
Using vehicles known as “deep-sea landers,” the study authors trapped amphipods living in the deepest parts of the trenches and tested them for PCBs and PBDEs. They found pollutants in all types of the crustaceans, in both trenches and at all depths samples, up to 10,000 meters deep in both locations. Average concentrations were higher in the Mariana Trench, the Post noted, with some testing at levels 50 times higher than crabs from China’s highly polluted Liaohe River.
“The very bottom of the deep trenches like the Mariana are inhabited by incredibly efficient scavenging animals… so any little bit of organic material that falls down, these guys turn up in huge numbers and devour it,” Jamieson told the Guardian. While he was not surprised to find some POPs in creatures living at such extreme depths, he said that the shocking thing was “just how high the levels were – the contamination in the animals was sky high.”
Katherine Dafforn, a senior research associate at the University of New South Wales in Australia and the author of a commentary accompanying the new study, called the findings “surprising and quite alarming.” As she explained to USA Today, “Chemicals that were produced, subsequently regulated and then largely eliminated before I was even born have continued to persist, and now we find evidence of them even in our deepest oceans.”
Image credit: NOAA Office of Ocean Exploration