Great Barrier Reef suffers unprecedented second year's bleaching
10 March 2017 Last updated at 20:41 GMT
Scientists in Australia say the Great Barrier Reef has been hit by widespread bleaching of its corals for the second successive year.
Experts from the Great Barrier Reef Marine Park Authority said their first aerial survey of 2017 showed large areas of the reef had become distressed by high water temperatures.
Coral can recover from bleaching, but this is the first time it has happened again within twelve months, increasing concerns over the reef's long term health.