Millions Of tons. That’s how much plastic should be floating in the world’s oceans, given our ubiquitous use of the stuff. But a new study finds that 99% of this plastic is missing.
Plastic junk is floating widely on the world’s oceans, but there’s less of it than expected, a study says. Such ocean pollution has drawn attention in recent years because of its potential harm to fish and other wildlife. The new work drew on results from an around the world cruise by a research ship that towed a mesh net at 141 sites, as well as other studies. Researchers estimated the total amount of floating plastic debris in Open Ocean at 7,000 to 35,000 tons.
Exactly what is happening to this ocean debris is a mystery, though the researchers hypothesize that the trash could be breaking down into tiny, undetectable pieces. Alternatively, the garbage may be traveling deep into the ocean’s interior.
“The deep ocean is a great unknown,” study co-author Andrés Cózar, an ecologist at the University of Cadiz in Spain, said in an email. “Sadly, the accumulation of plastic in the deep ocean would be modifying this mysterious ecosystem, the largest of the world before we can know it.”
One disturbing possibility: Fishes are eating it.
If that’s the case, “there is potential for this plastic to enter the global ocean food web,” says Carlos Duarte, an oceanographer at the University of Western Australia, Crawley. “And we are part of this food web.”
To figure out how much refuse is floating in those garbage patches, four ships of the Malaspina expedition, a global research project studying the oceans, fished for plastic across all five major ocean gyres in 2010 and 2011. After months of trailing fine mesh nets around the world, the vessels came up light, by a lot. Instead of the millions of tons scientists had expected, the researchers calculated the global load of ocean plastic to be about only 40,000 tons at the most, the researchers report online today in the Proceedings of the National Academy of Sciences. “We can’t account for 99% of the plastic that we have in the ocean,” says Duarte, the team’s leader.
Kara Lavender Law, who studies plastic pollution at the Sea Education Association in Woods Hole, Massachusetts, said the study provides the first global estimate she knows of for floating plastic debris. The estimate appears to be in the ballpark, given the results of prior regional studies, said Law, who didn’t participate in the new work.
“We are putting, certainly by any estimate, a large amount of a synthetic material into a natural environment,” Law said. “We’re fundamentally changing the composition of the ocean.”
The impact on fish and birds is hard to gauge because scientists don’t understand things like how much plastic animals encounter and how they might be harmed if they swallow it, she said.