Much of the plastic we produce on land ends up contaminating the sea. But when researchers went searching for a global picture of all the plastics stuck swirling around the gyres, they found that a massive amount—perhaps as much as 99%—was missing.
A tiny fish with a nightly fix for plastic may be one of the culprits.
As University of Western Australia Oceans Institute director Carlos Duarte explained in a lecture for the university's Inquiring Minds series, he and PhD student Julia Reiser anticipated they'd find plastics in excess of a million metric tons after sampling waters off the Australian coast and the world's five major gyres, or vortexes of ocean currents. Instead, they only found 10,000 to 30,000 metric tons.
"It's not that we weren't happy to find that little amount of plastic, but it's much less than we thought we would find," Duarte said. "This doesn't mean that plastic isn't being produced or released. It means that plastic is being lost at sea somewhere."
Duarte listed three possible ways in which the plastic might be hiding. The first could be that plastics are broken down by the sun into parts so spectacularly tiny that they weren't detected by the team's equipment. Another option could be bacteria beginning to feast on the particles. But Duarte and Reiser found that one size of plastic, bits to two to three centimeters long, was notably absent from their samples.
Curiously, that kind of plastic fits the fish food profile for the lanternfish, a small glow-in-the-dark organism with huge eyes that rises from depths of 500 to 700 meters at night to eat, then returns below to avoid predators during the day. "The size of the prey they eat is exactly the size of the plastic we're missing," Duarte said.
The lanternfish is also one of the most populous animals in the sea. Representing some 660 million tons of fish, it's estimated that the species could make up the majority of the ocean's living biomass.
And their guts could be one of the final resting places for all our discarded iPhone cases. When researchers cut the lanternfish open, they found evidence of the missing pieces.