The vast majority of debris in the ocean — about 75 percent of it — is made of plastic. It can consist of anything from plastic bottles to packaging materials, but whatever form it takes, it doesn't go away easily.
While plastic may break down into smaller and smaller pieces, some as small as grains of sand, these pieces are never truly biodegradable. The plastic bits, some small enough that they're called microplastics, threaten marine life like fish and birds, explains Richard Thompson, a professor of marine biology at Plymouth University in the U.K.
"The smaller the piece of debris, the more accessible it is — and the wider the range of creatures that could potentially eat it," says Thompson, who talked with NPR's Melissa Block about his research on the effects of these tiny particles.
Thompson says limiting the damage plastics can cause to sea life doesn't mean giving up plastic entirely. "It's not about banning plastics," Thompson says. "It's about thinking about the ways that we deal with plastics at the end of their lifetime to make sure that we capture the resource."
By recycling items like plastic bottles, he says, and then ultimately recycling those products again, what might have become harmful debris can be turned instead to better use — and kept out of the ocean.
You can hear Block's full conversation with Thompson at the audio link above.