Normally, around 4 percent of corals are fighting a disease, said Lamb. But where she and her study co-authors found plastic, corals were likely to be sick 89 percent of the time.
They documented a 20-fold increase in ailments like black band disease, skeletal eroding band disease, and white syndromes. Each involves bacteria and other critters killing the tiny polyps that produce the hard skeletons that comprise coral reefs. Lamb didn’t know why the diseases were taking hold, but she had ideas.
“It could be that plastics are shading the corals, corals are stressed and there is this low oxygen, low-light habitat that these bacteria really love,” she said.
The knock-on effects of the sicknesses are significant. Around 275 million people depend on corals in the region for food, tourism income, coastal protection, and other benefits, the researchers wrote.
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Lamb hoped her work would inspire people to use paper bags at the grocery store, potato starch bags for trash, reusable bottles for water, and take other measures. “The individual can make a conscious effort to reduce the amount of plastic we consume,” she said.
Governments and corporations could also ban plastic bags and similar items or force people to buy them, she added. “If I have to buy something, I’m very likely not to have it,” she said.
At least there’s a silver lining to the depressing findings. If humankind can reduce the amount of plastic in the seas, the corals will rebound.
“Corals are extremely resilient,” said Lamb. “They are fighters. If you went and took all the plastic off, they would have a fighting chance. Even if they do die, that’s still a substrate for a baby coral to land on. That could proliferate for a whole new colony.”