The health of corals like those found on the Great Barrier Reef is under threat from tiny pieces of plastic in the ocean.

Researchers in Australia put corals collected from the Great Barrier Reef into water that contained microplastics — tiny fragments of plastic debris that are seen throughout marine ecosystems.

After two nights the corals had eaten plastic particles, according to a report by the ARC Centre of Excellence for Coral Reef Studies at James Cook University.

It seems that the corals mistake the plastics for the tiny creatures they normally feed on.

"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," explained study lead author Nora Hall, a James Cook University Masters graduate.

"We found that the corals ate plastic at rates only slightly lower than their normal rate of feeding on marine plankton."

The researchers expressed concern that ingestion of high concentrations of microplastics might impede the corals' ability to digest their normal food, as the plastic was found deep inside the coral polyp wrapped in digestive tissue.

As part of their study, the team sampled the waters adjacent to inshore coral reefs on the Great Barrier Reef. This revealed the presence of microplastics similar to those used in marine paints and fishing floats, including polystyrene and polyethylene, although only in small amounts.

The next step will be to determine the impact of microplastic pollution on coral physiology and health, as well as its impact on other marine life.