Coral species prefers microplastics to real food

June 27 (UPI) -- At least one coral species has a taste for microplastic pollution. According to a new study, the coral species Astrangia poculata prefers the tiny plastic bits to its normal diet.

As a number of studies have shown, microplastics are increasingly common in the ocean, and are showing up in a wide variety of ecosystems, including the deep sea, and in the intestines of a variety of marine organisms.

"Plastics keep interrupting the conversation, and it's hard to ignore," Randi Rotjan, Boston University coral biologist, told National Geographic. "You pick your ecosystem, you pick your organism, and you are most likely going to find microplastics."

To better understand the effects of microplastics on corals, researchers collected Astrangia poculata coral from just off the coast of Rhode Island, not far from Providence. Scientists suspected corals living near an urban center would be more likely to be polluted by microplastic debris.

When scientists dissected the coral in the lab, they found each individual coral, or polyp, contained more than 100 pieces of microplastic bits. Researchers also placed some of the collected corals in a tank of seawater and showered them with both microplastics and shrimp eggs, a favorite food. After a few days in the tank, scientists cut the corals open and found twice as much microplastic debris as shrimp eggs.

In a followup study, scientists placed microplastic beads in the ocean and allowed a biofilm to grow on them. Researchers infused the biofilm with E. coli bacteria and fed them to coral. Though the coral spit the beads out after two days, the coral died from the infection a few days later.

The findings, published this week in the Proceedings of the Royal Society B, suggest microplastic pollution could be introducing bacterial infections to vulnerable coral.

"Can we conclude that corals in the wild are being threatened by plastics in the same way they're being threatened by warming temperatures and bleaching and acidification? We just don't know the answers to those questions yet," Kara Lavender Law, an oceanographer at the Sea Education Association in Woods Hole who wasn't involved in the study, told WBUR.

"There's a good reason for us to be concerned, even if we don't know exactly what's happening," Law said.