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Corals Eat Plastic

Researchers have reported that corals commonly found on the Great Barrier Reef will eat microplastic pollution.

Microplastics are tiny fragments of plastic in the environment, and are a widespread contaminant in marine ecosystems, particularly inshore coral reefs. Despite the proliferation of microplastics, their impact on marine ecosystems is poorly understood.

“Corals are non-selective feeders, and our results show that they can consume micro­­plastics when the plastics are present in seawater,” says Dr Mia Hoogenboom of the ARC Centre of Excellence for Coral Reef Studies at James Cook University. “If microplastic pollution increases on the Great Barrier Reef, corals could be negatively affected as their tiny stomach cavities become full of indigestible plastic,” Hoogenboom warns.

The researchers put corals collected from the Great Barrier Reef into plastic-contaminated water. After two nights they found that the corals had eaten plastic particles.

“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,” says lead author of the Marine Biology paper, Nora Hall. “We found that the corals ate plastic at rates only slightly lower than their normal rate of feeding on marine plankton,” she says.

The plastic was found deep inside the coral polyp wrapped in digestive tissue, raising concerns that it might impede the coral’s ability to digest its normal food.

The team also sampled the waters adjacent to inshore coral reefs on the Great Barrier Reef. “During this testing we found micro­plastics, including polystyrene and poly­ethylene, although only in small amounts,” says co-author Kathryn Berry, a PhD student at James Cook University and the Australian Institute of Marine Science.

The researchers say the next step is to determine the impact plastic has on coral physiology and health, as well as its impact on other marine organisms. “We are also investigating whether fish on coral reefs eat plastics, and whether plastic consumption influences fish growth and survival,” Hoogenboom says.