Where’s All The Plastic Going?

Bottlenose dolphin (Tursiops truncatus) swimming in oil slick, black plastic bag is along belly Curacao, Netherlands Antilles

The ocean should be a lot more plasticky than it actually is:

For a decade or more, scientists have assumed our seas carry millions of tons of plastic, much of which should be floating in open water, forming vast midocean “gyres” – islands of man-made mess such as the Great Pacific Garbage Patch. But according to a new study, something more worrying is happening to 99 percent of the ocean’s plastic: it’s disappearing.

The study outlines the findings of scientists who trawled the waters around five large ocean gyres in 2010 and 2011. The data they obtained put them far short of the expected amount of plastic in the ocean — rather than millions of tons, the global load of ocean plastic was calculated at 40,000 tons at most.

So what happened?

Though it’s possible that sunlight is eroding it into nothingness, or that tiny pieces are washing back ashore, researchers are skeptical. What’s probably happening, scientists theorize, is that tiny fish are eating it. The most likely plastic-snackers are lanternfish and other small “mesopelagic” species, meaning those that live in the middle swath of the ocean, swimming to the surface at night to feed. These are far and away the most populous fishes in the sea. …

We don’t have a good sense of what swallowing plastic does to these fish, or even whether they’re able to excrete or throw up their plastic meals. That’s worrisome, since the toxic chemicals in plastic might permeate their tissue – bad for mesopelagic fish, but also potentially bad for humans. Pellets in the 0.5-5-millimeter range are also commonly found in the bellies of the predators who eat these smaller fish, according to the study. Those include tunamackerel and other sushi-menu faves.

For the larger chunks of plastic, drones could help:

[G]etting to the scale needed to map the world’s ocean garbage will require a gigantic remote-controlled swarm of nautical drones. Ultimately the idea is to deploy thousands of swarming, meter-long sailboats equipped with sensors and dragging nets behind them to scoop up the garbage.

Protei’s shape-shifting robotic hull is the project’s breakthrough technology, and the design is open source for anyone to use. The hull bends and curves like a snake in order to control the boat’s trajectory through the water. Touted as unsinkable, self-righting, and hurricane-ready, the drone uses wind power, and the latest prototype can tow a payload of under five pounds, the group claims. The vessel would use a custom plastic sensor to locate the trash; the sensor is able to measure “slices” of pollution at various depths.

Recent Dish on plasticky sedimentary rocks here.

(Photo: A bottlenose dolphin (Tursiops truncatus) swims in oil slick alongside a black plastic bag off the shore of Curacao, Netherlands Antilles. By Wild Horizons/UIG via Getty Images)