Alan Jamieson, a marine biologist at Newcastle University, has been sending vehicles to the bottom of oceanic trenches to study and collect amphipods, relatives of crabs and shrimp, for the past decade. His studies were initially aimed at discovering differences in these tiny animals from one trench to another. A few years ago, however, Jamieson decided to examine their bodies for toxic, human-made pollutants, including polychlorinated biphenyls (PCBs). Although PCBs have been banned for decades, testing for their presence today is still relevant, as they are known to linger in nature for a very long time.
Jamieson’s team found high amounts of PCBs in the amphipods tested and some had levels 50 times greater than levels seen in crabs from one of China’s most contaminated rivers. After these results were made public, the biologist received numerous calls from concerned citizens and journalists, of which most ended up asking him about plastics. Plastic is known to float in surface waters of the ocean as well as in the water column, but plastic particles can and do eventually sink.
Lauren Brooks, one of Jamieson’s students, ended up finding plastic fibers and fragments in 72% of the amphipods the team collected across six different trenches. And in the Mariana Trench, which stretches 6.8 miles deep (making it the lowest point of all the oceans), every single specimen had plastic in their guts. Amphipods are skilled scavengers. They purposely pump water over their bodies to help pick up the faintest of scents and even have taste buds on their legs. Because food is scarce in this deep, remote environment, amphipods don’t have the luxury of being picky eaters. And since these animals will eat anything possible, this makes them especially vulnerable to eating plastics.
Researchers worry that if distant places such as these trenches are contaminated, then likely every part of the ocean is no longer untouched by plastic. Jamieson stated, “What you put in the trench, stays in the trench.” And this means the plastic problem will only get worse. Just last year, other scientists found a plastic bag at the bottom of the Mariana Trench. The fact that these amphipods are at the bottom of the trench food web and are eating plastic could be detrimental to entire ecosystems. Jamieson plans to test a hypothesis in later studies where they would see if amphipods from deeper parts of the same trench have higher levels of plastics than those found higher up in the trench.
There is already a growing body of evidence that suggests the deep sea to be one of the largest reservoirs of plastic waste on the planet, but now is the time to put stricter policies in place and not the time to wait to adopt more responsible practices.