91% of corals studied have bleached along the Great Barrier Reef, Australia says

SYDNEY – More than 90% of coral reefs surveyed along Australia’s Great Barrier Reef have been bleached in recent months due to catastrophically warm ocean temperatures, according to a new report from the main government agency monitoring the health of the structure.

The Great Barrier Reef Marine Park Authority released its “Reef Snapshot” report on Tuesday after carrying out aerial surveys of the structure following reports that it was suffering from massive bleaching earlier this year. Researchers monitored 719 reefs along Australia’s east coast, saying 654 of them showed signs of at least some bleaching. Many of them have been classified as severely or extremely bleached.

“The waters of the Great Barrier Reef warmed in early December 2021, exceeding historic summer highs that typically occur during the hottest summer months,” the agency said in a statement this week. “This prolonged heat exposure has resulted in massive coral bleaching across the Great Barrier Reef; the fourth to occur in seven years. Unusually, this was the first mass bleaching event to occur under La Niña conditions.

The marine park authority said on Tuesday that scientists had observed severe bleaching along some surveyed sites, including “completely white colonies” and coral death in areas hit hardest by warm oceans.

The marine park authority first said in March that the iconic structure was suffering another devastating mass bleaching event, the fourth since 2016, due to abnormally warm ocean temperatures. This is the first time, however, that massive bleaching has occurred in a La Niña year, when the ocean is supposed to be cooler than usual.

Bleaching most often occurs when corals are effectively cooked by hotter water than usual, causing the delicate polyps to turn sickly white. They can recover if temperatures stabilize, but if the warm water persists for too long, huge swaths of the reef can die.

This is the fourth time the Great Barrier Reef has experienced massive bleaching since 2016, and the first in a colder La Niña year.

Great Barrier Reef Marine Park Authority

The report was released quietly on Tuesday evening, a week after the Sydney Morning Herald reported the document had been delayed until after the Australian federal election. The Great Barrier Reef Marine Park Authority argued at the time that the decision had nothing to do with politics, although scientists and conservationists criticized the agency for not releasing the results sooner.

The agency’s chief scientist, David Wachenfeld, said there was hope the bleaching would not cause widespread coral death.

“Early indications are that the mortality will not be very high, so hopefully we will see most of the bleached corals recovering, and we will end up with an event a bit more like 2020 where yes, there has been massive bleaching but there was low mortality,” Wachenfeld told the Australian Broadcasting Corporation.

This photo taken on March 7, 2022 shows a diver swimming among corals in the Great Barrier Reef, off the Australian state of Queensland.
This photo taken on March 7, 2022 shows a diver swimming among corals in the Great Barrier Reef, off the Australian state of Queensland.

GLENN NICHOLLS via Getty Images

But reef advocates have stressed that any mass bleaching event is devastating news.

“It was a La Niña year, normally characterized by more cloud cover and rain,” Lissa Schindler, campaign manager for the Australian Marine Conservation Society, told The Guardian. “It should have been a welcome reprieve for our reef to help it recover… This is not normal and we should not accept that this is the way things are.”

Australian Prime Minister Scott Morrison has come under heavy criticism for failing to tackle climate change, instead throwing his support behind the coal and mining industries. The country has pledged to spend more than $2 billion to protect the structure, but supporters say that figure doesn’t address the root cause of its demise: our rapidly warming world.

Scientists had hoped the season would give corals hit by frequent bleaching time to recover, but said the latest event was a “darksign for the future of the reef. Instead, some have warned that the next strong El Niño summer – when the waters are warmer than usual – will be “horrendous” for the reef.


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