It's easy to assume that the ocean's deepest points have remained largely untouched by humanity, especially given that such depths range from 26,000 to 36,000 feet under the surface. But a new study published in Nature Ecology & Evolution finds that these alien environments are shockingly rich in toxic chemicals.
A team of researchers led by Alan Jamieson of Newcastle University in England recently sent remotely operated vehicles with bait traps into the Mariana and Kermadec trenches of the Pacific Ocean. Both trenches teem with life at 30,000 feet deep. This video shows just how popular these traps were with marine life:
After catching a number of small crustaceans called amphipods, the scientists were surprised to discover that the creatures contained more toxins than comparable crustaceans living in some of the world's most polluted rivers.
"In fact, the amphipods we sampled contained levels of contamination similar to that found in Suruga Bay, one of the most polluted industrial zones of the northwest Pacific," Jamieson said in a statement. "What we don't yet know is what this means for the wider ecosystem and understanding that will be the next major challenge."
Banned chemicals resurface
The toxins discovered within the amphipods included polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs); chemicals that were commonly used for nearly four decades until being banned in the late 1970s. An estimated 1.3 million tons were produced during that time, with some 35 percent of it ending up in coastal sediments and open ocean. Because these types of pollutants are resistant to natural degradation, they have continued to persist in the environment.
The researchers theorize that the extreme levels found in the trenches may be a result of deep sea creatures consuming both plastic debris and the contaminated carcasses of dead animals sinking from above.
"The fact that we found such extraordinary levels of these pollutants in one of the most remote and inaccessible habitats on Earth really brings home the long term, devastating impact that mankind is having on the planet," Jamieson added. "It's not a great legacy that we're leaving behind."
The next step for the researchers will be to determine the impact of the toxins on the trench ecosystem and the steps, if any, that can be taken to avoid further imperilment of a deep sea world we're only just beginning to shed light on.