Super Thin Shield for Stressed Reefs
Researchers have invented a biodegradable sunscreen which they hope could protect the world's largest barrier reef from the impact of climate change.
The spray is only one molecule thick and about 50,000 times thinner than a human hair and sits on the surface of water above corals to provide a barrier against the sun’s UV and visible light.
Tests at the Australian Insititute of Marine Science have found that the screen reduced bleaching in most species of coral by blocking up to 30 per cent of sunlight.
Andrew Negri, of the Institute, said: 'It is white so it reflects and scatters all the light which hits the ocean surface.
The spray is made up of calcium carbonate, the same ingredient corals use to make their hard skeletons, and a natural lipid.
Dr Negri said both materials could naturally be found in sediments along the coral reef.
'In the laboratory it actually stays on the surface for several weeks but in the ocean, it could be broken up by wave action and moved around by the currents,' he said.
'Some of it will sink to the bottom of the sea floor like sediment and some of it will just remain floating on the surface and...will eventually be degraded...quite rapidly.'
It is hoped that the spray, developed by the same team which came up with polymer banknotes, could be used to protect areas of the reef that are particularly at threat from bleaching. Coral starts to bleach when water temperatures exceed 29ºC. The Great Barrier Reef suffered back-to-back bleaching events last year and the year before and is now seriously under threat as coral cover needs years to recover.
Great Barrier Reef Foundation managing director Anna Marsden said: 'The idea being that you could in the future, knowing there is going to be hot days ahead...spray this film on top of key reefs that are high value or highly productive or key tourism sites and this will act as a bit of a shield...almost like an umbrella, to protect these reefs underneath and the animals underneath.
'This is parallel of course to the bigger challenges...we have to mitigate against climate change, we have to do that plus we can look at other things we can do to try and protect some of the reefs in the short term.'