Plastic Pollution is Infecting 89 Percent of Coral Reefs

A piece of plastic floats over a coral reef
Kathryn Berry

Coral reefs are meant to be riots of color, but those that Joleah Lamb studied in the Indo-Pacific were colorful for all the wrong reasons. Their branches and crevices were frequently festooned with plastic junk. “We came across chairs, chip wrappers, Q-tips, garbage bags, water bottles, old nappies,” she says. “Everything you see on the beach is probably lying on the reef. And it seems like it’s getting worse.”

Whenever Lamb or her colleagues from Cornell University found a piece of plastic, they would lift it up to study the health of the coral underneath. And almost every time, that coral would be riddled with disease. “It’s just a disaster under there,” she says.

Over four years, the team analyzed more than 124,000 corals, spanning 159 reefs in four countries: Myanmar, Thailand, Indonesia, and Australia. They found that under normal circumstances, just 4 percent of corals are afflicted by some kind of disease. But infections strike down 89 percent of corals that come into contact with plastic.

“I didn’t think we would be the ones to write this study,” says Lamb, because other scientists have already done so much research on plastic pollution. They’ve estimated that 5 trillion tiny pieces of plastic float in the seas. They’ve shown that some gets swallowed by seabirds because it smells like food. They’ve documented plastic waste on the shores of the world’s remotest islands.

But to Lamb’s surprise, no one had really estimated the extent of plastic junk on coral reefs, or studied how that junk relates to disease. Indeed, when people think about the many ills befalling reefs—rising temperatures, acidifying waters, overfishing, nutrient pollution, ravenous starfish—plastic rarely gets a mention.

Worse still, plastic-induced ailments disproportionately affect the corals that provide important habitats for fish—the ones that create intricate branches and layers. That same architectural complexity becomes easily filled and entwined with plastic, so these corals are eight times more likely to be diseased than simpler ones with rounded shapes.

In fairness, not all reefs are strewn with plastic. Lamb never saw much of it in the Great Barrier Reef, for example. But “in Indonesia, we were seeing 26 pieces of plastic in an area the size of a Manhattan two-bedroom apartment,” she says. The Asia-Pacific region is home to eight of the world’s top 10 plastic-polluting countries, and more than half of the world’s coral reefs. According to estimates from Lamb’s team, those reefs are currently covered with around 11 billion pieces of plastic—and that’s likely a gross underestimate because it doesn’t account for contributions from China, the world’s top plastic polluter.


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SOURCE: The Atlantic, Ed Yong