Corals developing taste for plastics, scientists say

Scientists conducted their two-part study using corals collected from waters off the North Carolina coast.

Just like humans, corals are drawn to food that is bad for them, it would seem. The researchers tested corals they had collected off the North Carolina coast, by giving them a variety of options to eat, including bits of sand and plastic.

The corals largely ignored the bits of sand and went for the plastic.

“Corals in our experiments ate all types of plastics but preferred unfouled microplastics by a threefold difference over microplastics covered in bacteria,” says Austin Allen, a PhD student at Duke University’s Nicholas School of the Environment. “This suggests the plastic itself contains something that makes it tasty.”

The plastic can’t be mistaken for prey because coral don’t have eyes, so they have no way of seeing what they are about to eat. The researchers think some of the chemicals found on the plastic might be making it taste nice to the coral.

“When plastic comes from the factory, it has hundreds of chemical additives on it. Any one of these chemicals or a combination of them could be acting as a stimulant that makes plastic appealing to corals,” says Alexander C. Seymour, a geographic information systems analyst at Duke’s Marine Robotics and Remote Sensing Center, who co-led the study with Allen.

The next step will be to identify which of the additives are making it so tasty, and see if other marine animals feel the same way about it.

While corals might like the taste of plastic, it does not mean it is good for them to consume it. Plastic is almost completely indigestible, so it causes blockages, create a false sense of being full, or reduce the energy reserves in animals that eat it. “About 8% of the plastic that coral polyps in our study ingested was still stuck in their guts after 24 hours,” says Allen.

By understanding why coral is drawn to plastic pollution, the authors hope they can combat some of these problems.

“Ultimately, the hope is that if we can manufacture plastic so it unintentionally tastes good to these animals, we might also be able to manufacture it so it intentionally tastes bad,” Seymour says. “That could significantly help reduce the threat these microplastics pose.”

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