Ultra-thin sun shield could protect Great Barrier Reef

An ultra-fine biodegradable film some 50,000 times thinner than a human hair could be enlisted to protect the Great Barrier Reef from environmental degradation, researchers said today.

The World Heritage-listed site, which attracts millions of tourists each year, is reeling from significant bouts of coral bleaching due to warming sea temperatures linked to climate change.

Scientists from the Australian Institute of Marine Biology have been buoyed by test results of a floating "sun shield" made of calcium carbonate that has been shown to protect the reef from the effects of bleaching.

"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," Great Barrier Reef Foundation managing director Anna Marsden said.

The trials, headed by the scientist who developed the country's polymer bank notes, on seven different coral types found that the protective layer decreased bleaching of most species, cutting off sunlight by up to 30 percent.

"It (the project) created an opportunity to test the idea that by reducing the amount of sunlight from reaching the corals in the first place, we can prevent them from becoming stressed which leads to bleaching," Marsden said.

With its heavy use of coal-fired power and relatively small population, Australia is considered one of the world's worst per capita greenhouse gas polluters, with advocates urging Canberra to do more to protect the environment.

The reef is also under threat from the predatory coral-eating crown-of-thorns starfish as well as farming run off.

Marsden said it was impractical to suggest that the "sun shield" -- made from the same material found in coral skeletons -- could cover the entire 348,000 square-kilometre (216,000 square-mile) reef.

"But it could be deployed on a smaller, local level to protect high value or high-risk areas of reef," she added.

"The concept needs more work and testing before it gets to that stage, but it's an exciting development at a time when we need to explore all possible options to ensure we have a Great Barrier Reef for future generations."