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Billions of pieces of plastic spread disease in coral reefs

Sep 30, 2021

It’s no secret that the world’s coral reefs are in bad shape.

Climate change has led to widespread coral bleaching. Overfishing has disrupted the ecosystems that keep reefs healthy.

Toxic runoffs from human industry are destroying the so-called “rainforests of the sea.” A new study has highlighted the distressing scope of yet another threat to coral reefs: plastics. That's according to Ed Yong, reporting for the Atlantic.

The study was published in the journal Science. Researchers analyzed more than 124,000 corals from 159 reefs. The reefs were in Myanmar and Thailand. They were also in Indonesia and Australia. Almost everywhere they looked, they saw bits of plastic.

“We came across chairs, chip wrappers, Q-tips, garbage bags, water bottles, old nappies,” said Joleah Lamb. She is a marine disease ecologist at Cornell University. She is also the lead author of the study. “Everything you see on the beach is probably lying on the reef.”

The team estimates that at least 11 billion plastic items are trapped in coral reefs in the Asia-Pacific. And they believe that number will increase by 40 percent by 2025. This could spell disaster for the world’s reefs. The team found that the likelihood of the corals developing a disease jumps from four to 89 percent when corals come into contact with plastics.

Further investigations are needed to determine precisely how and why plastics make coral open to different diseases. But generally speaking, it seems that plastic debris slices open the skin of the corals. This exposes them to pathogens.

“Plastic debris can cause physical injury and abrasion to coral tissues. It does so by facilitating invasion of pathogens or by exhausting resources for immune system function during wound-healing processes,” the authors of the study write.

Drew Harvell is a professor of marine ecology. He works at Cornell. He is co-author of the study. He tells Darryl Fears of the Washington Post that plastics also “shade the light coral needs and cut off water flow.”

It is vital to preserve the health of coral reefs for a number of reasons. For one, many marine creatures make their homes within the reefs. The reefs support “more species per unit area than any other marine environment.” That's according to the NOAA. Reefs also protect coastlines from waves and tropical storms. They support both local and international fishing industries. They also generate billions of dollars for the worldwide tourism industry every year.

Throughout the course of their research, scientists involved in the new study noticed that the plastics problem was not evenly distributed. Reefs near Indonesia had the highest amount of plastic trash, while reefs near Australia had the lowest. This could be because Australia boasts the best waste removal system. It suggests that there is a relatively easy fix to the issue.

“We can clean up the problem,” Harvell told Fears. “It’s so much easier than climate change.”

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