Researchers have discovered that corals living on Australia’s Great Barrier Reef will eat microplastic. And that’s not a good thing.
On its face, the idea that a marine animal can eat plastic gives the impression that the plastic goes away. With some 269,000 tons of it floating in the ocean – and most of it still unaccounted for – that would be great news. Except there’s this: Just because animals are eating plastic, that doesn’t mean they’re digesting it.
Much like the albatrosses living on the Midway Atoll, the coral are consuming the plastic particles in the ocean until they’re stuffed to capacity. Unlike the albatrosses, the coral don’t have a choice.
“Corals are non-selective feeders and our results show that they can consume microplastics when the plastics are present in seawater,” Dr. Mia Hoogenboom, a Chief Investigator with the ARC Center of Excellence for Coral Reef Studies at James Cook University and a co-author of “Microplastic ingestion by scleractinian corals,” published this month in the journal Marine Biology.
In an experiment, Hoogenboom and her colleagues put corals collected from the GBR into plastic-contaminated water. After two nights, they found that the coral had eaten all the plastic particles. Upon dissecting the corals, the researchers found plastic deep inside the coral polyp and wrapped in their digestive tissue. This could potentially interfere with their normal feeding.
Plastic does not biodegrade. Instead, over time and under the influence of light and heat, it steadily breaks down into smaller particles until it becomes microplastic – pieces that are indistinguishable from the plankton that forms the foundation of the marine food chain.
“Corals get energy from photosynthesis by symbiotic algae living within their tissues, but they also feed on a variety of other food including zooplankton, sediment and other microscopic organisms that live in seawater,” Nora Hall, a James Cook University Masters graduate and the lead author of the study, said in a media release.
“We found that the corals ate plastic at rates only slightly lower than their normal rate of feeding on marine plankton,” she added.
The researchers also tested the contents of the waters adjacent to the coral reefs of the GBR and found concentrations of microplastics, including polystyrene and polyethylene.
Late last year, the 5 Gyres Institute published the first-ever global estimate on microplastic pollution. After six years of traversing the globe and gathering data, they reported that there are 5.25 trillion particles of plastic currently floating in the ocean.