Scientists in Australia have developed an ultra-thin “sun shield” that could float on the water surface in the Great Barrier Reef to protect its coral from further bleaching.

Created from a biodegradable film that is 50,000 times thinner than a human hair, the shield has reduced sunlight by up to 30 per cent without damaging the coral.

The shield is sprayed onto the water as a solution and forms a white floating film, which keeps the water cooler and darker.

Scientists believe it could potentially help to prevent further bleaching in the Great Barrier Reef, the world’s largest marine reserve, which has come under threat from warmer water temperatures and increasing ocean acidity.

“The ‘sun shield’ is... completely biodegradable, containing the same ingredient corals use to make their hard skeletons – calcium carbonate,” said Anna Marsden, from the Great Barrier Reef Foundation.

“It’s designed to sit on the surface of the water above the corals, rather than directly on the corals, to provide an effective barrier against the sun.”