Great Barrier Reef bleached from top to bottom
THE Great Barrier Reef has been hammered by record undersea temperatures, with all three sections from Gladstone to Torres Strait now bleached and at risk of dying.
About 60 per cent of the reef is affected, according to aerial survey results released by Professor Terry Hughes from the ARC Centre of Excellence for Coral Reef Studies at James Cook University.
It follows major bleaching events in 2016 which killed 30 per cent of corals and in 2017, which killed another 20 per cent.
This time the northern, middle and southern sections are simultaneously affected, for the first time on record.
Although inshore reefs have been hardest hit, in a stroke of luck for beleaguered tour operators the major tourist drawcards off Cairns, Port Douglas and the Whitsundays have been spared.
Coral bleaches, or turns white, when it expels the colourful photosynthetic algae it needs to survive after prolonged periods of above-average water temperatures.
Undersea temperatures on the GBR in February were the highest ever recorded.
University of Queensland School of Biological Sciences head, Selina Ward, who is also the academic director at the Heron Island research station, said it would take months before it was known how much of the reef would recover.
"In 2016 it was a different scenario - many corals died straight away,'' Dr Ward said.
"Something that scares most of us is, like in 2017, this is not an El Nino year.
"We have to assume now that temperatures are (routinely) as high as in El Nino years.''
During El Ninos eastern Australia is thrown into drought and long stretches of sunny, hot days puts coral at high risk.
Dr Ward said although there had been recovery in some areas after the 2016 and 2017 events, there had been a shift in coral types after fast-growing species were wiped out.
"While it is concerning the southern section has been affected this time it is not everywhere - Lady Elliot Island looks good and Heron Island was lucky to have 11 days straight of rainy, cloudy weather,'' she said.
"The southern section should recover, although we can't now for sure yet.
"Corals can recover in as little as six weeks.''
Cairns-based Deborah Dickson-Smith, from Diveplanit Travel said the bleaching surveys once again highlighted the importance of tackling climate change.
"Prime tourist sites offshore from Port Douglas, Cairns and the Whitsundays have mercifully avoided severe bleaching, with the Great Barrier Reef Marine Park Authority saying corals in these areas should recover,'' she said.
"This is good news as we look to the other side of this pandemic.
"But we know that our Reef is under serious threat from climate change and we need our leaders to put in place strong climate and energy policies to protect its future and that of our businesses."
Australian Marine Conservation Society GBR campaigner, David Cazzulino, said: "This is climate change impacting our Reef from the north to the south.
"It shows the urgent need for reef-safe climate policies to protect our reef and the communities that love and rely on it.
"Tourism operators reveal the beauty of our iconic Great Barrier Reef to the world. We need to support them in the short and long term by demanding government policy that gets industries through this pandemic and sustains the Reef and their livelihoods long term.
"The only way to do that is take action to cut our emissions.
"Only bold action on climate change will give our reef the best chance for the future.''
Originally published as Great Barrier Reef bleached from top to bottom