A first of Its kind map reveals the extent of ocean plastic. There’s less than expected on the surface and scientists are trying to find where in the ocean it’s gone. Something doesn’t quite add up. Of the nearly 300 million tonnes of plastic now produced annually by the world’s 192 coastal countries, an estimated 8.8 million tonnes ends up in the world’s oceans. Most comes from Asian countries where rivers are disposal systems. About one billion microplastic pieces reach the Pacific each day from southern California cities. But 99% is missing disappearing into the marine ecology.
There are millions of pieces of plastic debris floating in five large subtropical gyres in the world’s oceans. But plastic production has quadrupled since the 1980s, and wind, waves, and sun break all that plastic into tiny bits the size of rice grains. So there should have been a lot more plastic floating on the surface than the scientists found. Observations show that large loads of plastic fragments, with sizes from microns to some millimeters, are unaccounted for in the surface loads. It is not known what this plastic is doing. The plastic is somewhere—in the ocean life, in the depths, or broken down into fine particles undetectable by nets.
What effect those plastic fragments will have on the deep ocean—the largest and least explored ecosystem on Earth—is anyone’s guess. The accumulation of plastic in the deep ocean could be modifying this enigmatic ecosystem before we can really know it.
But where exactly is the unaccounted-for plastic? In what amounts? And how did it get there?
No beach or body of water on earth is free of discarded plastic. Water from the British Columbia coast was found to contain 9,180 pieces of plastic per cubic meter in some locations – each piece about the size of a coffee ground. Concentrations were usually higher closer to urban centers. Microplastics are ingested by small copepods, the first step in the migration of these wastes up the food chain to us.
Plastic, Plastic Everywhere
One reason so many questions remain unanswered is that the science of marine debris is so young. Plastic was invented in the mid-1800s and has been mass-produced since the end of World War II. In contrast, ocean garbage has been studied for slightly more than a decade. People always thought that the solution to pollution was dilution, meaning that we could turn our head, and once it is washed away, it was out of sight and out of mind.
The North Pacific Garbage Patch, a loose collection of drifting debris that accumulates in the northern Pacific, first drew notice when it was discovered in 1997 by adventurer Charles Moore as he sailed back to California after competing in a yachting competition. A turning point came in 2004, when Richard Thompson, a British marine biologist at Plymouth University, concluded that most marine debris was plastic.
Research on marine debris is also complicated by the need to include a multidiscipline group of experts, ranging from oceanographers to solid-waste-management engineers. We are at the very early stages of understanding the accounting. If we think ten or a hundred times more plastic is entering the ocean than we can account for, then where is it? We still haven’t answered that question. And if we don’t know where it is or how it is impacting organisms, we can’t tell the person on the street how big the problem is.
New Maps Document Floating Plastic Trash
Tens of thousands of tons of plastic garbage float on the surface waters in the world’s oceans, mapped giant accumulation zones of trash in all five subtropical ocean gyres. Ocean currents act as “conveyor belts,” researchers say, carrying debris into massive convergence zones that are estimated to contain millions of plastic items per square kilometer in their inner cores.
To assess the level of plastic pollution, a two-ship expedition spent nine months circumnavigating the world. They also used data gathered by four other ships that had traveled to the polar regions, the South Pacific, and the North Atlantic to complete the map.
3,070 water samples were analyzed. One of the most striking observations was the conspicuous presence of plastic in the surface samples, even thousands of kilometers from the continents. The plastic garbage patch in the South Atlantic Gyre was one of the most striking.
Some of the tiniest bits of plastic are being consumed by small fish, which live in the murky mesopelagic zone, 600 feet to 3,300 feet (180 to 1,000 meters) below the surface. Little is known about these mesopelagic fish other than that they’re abundant. They hide in the darkness of the ocean to avoid predators and swim to the surface at night to feed. One of the most common mesopelagic fish is the lantern fish, which lives in the central ocean gyres and is the main link in the tropical zone between plankton and marine vertebrates. Because lantern fish serve as a primary food source for commercially harvested fish, including tuna and swordfish, any plastic they eat ends up in the food chain.
There are signs enough to suggest that plankton-eaters, the small fishes, are important conduits for plastic pollution and associated contaminants. If this assumption is confirmed, the impacts of a man-sustained plastic pollution could extend over the ocean predators on a large scale.