All of those hastily discarded plastic water bottles start to add up.
Thousands of miles off the coast of California, millions of tons of plastic make up the so-called "Great Pacific Garbage Patch"—and as it breaks down, it becomes more enticing to the creatures living in the open ocean.
"Most of the animals out there are really small, which is why we're more concerned about having millions of tiny pieces of plastic than having a couple big pieces," says Miriam Goldstein, of the Scripps Institution of Oceanography at the University of California San Diego.
Goldstein's latest report, published Tuesday, estimates that particles of "microplastic"—pieces of plastic smaller than 5 mm in diameter—have increased by more than 100 times since the early 1970s. Last year, her team found that nearly 10 percent of fish in the area had eaten plastic.
"We know fish, mammals, and birds often mistake pieces of plastic for food," says Dianna Parker, of NOAA's Marine Debris Program. "We've heard of albatross that live in the northwestern Hawaiian islands found dead with their stomachs full of plastics."
The garbage patch spans hundreds of thousands of square miles—it's either the size of Texas, or twice the size of the United States, depending on who you ask—but it's not exactly the "giant floating island of trash" some have made it out to be.
"It's not really easy to see. The ocean looks like the ocean anywhere else, although you will see larger pieces of trash floating by," Goldstein says. "But if you put a net in the water, you'll grab hundreds of thousands of tiny pieces of plastic."
But there are plenty of larger pieces as well: fishing nets, buoys, plastic bottles—Goldstein even found a stuffed toy dog.
The patch formed due to oceanic gyres—rotating systems of ocean currents that have a whirlpool-like effect on debris. In the center, there is very little current, leaving all the plastic stuck in one giant spot. Similar garbage patches have formed in the Atlantic Ocean and in the Southern Hemisphere, although the Pacific Ocean patch is believed to be the largest and most-studied.
Experts disagree on where most of the plastic comes from—some have estimated that 80 percent of it comes from land sources, others say more of it is from shipping junk—but they agree there's little the public can currently do about it. While plastic breaks down into smaller pieces, it never fully decomposes, so what's left behind in the ocean is there indefinitely.
"From our perspective, the solution is preventing this type of debris from entering the ocean in the first place," NOAA's Parker says. "Cleaning it up would be a tremendous challenge. It wouldn't be cost effective to skim the surface of the ocean—to our knowledge, nobody has really even tried to clean it."
Goldstein's study found that it might be having an impact on a type of insect that lives on the open ocean. Sea-skaters, which glide along the surface of the ocean, may have adapted to lay eggs on the piles of trash. In areas with more microplastics, the team found many more sea-skater eggs. What the proliferation of these insects mean is a wildcard, Goldstein says.
"These guys are predators, they eat plankton and are eaten by fish and seabirds … generally, food is hard to come by out on the open ocean," she says. "With more of them living on the sea surface, it could really change the way energy is moving through the ecosystem."
Jason Koebler is a science and technology reporter for U.S. News & World Report. You can follow him on Twitter or reach him at firstname.lastname@example.org.