Alert has been issued for the Great Barrier Reef as corals begin to bleach

By Australian Geographic February 20, 2020
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THE ALARM HAS been sounded after significant bleaching to northern parts of the Great Barrier Reef, with a possible mass bleaching to occur in the coming weeks.

The chief scientist at the Great Barrier Reef Marine Park Authority David Wachenfeld said surveys had discovered bleaching at three reefs just off Cape York.

According to David, because the Great Barrier Reef Marine Park is now at 2–3°C above normal temperatures, the threat of a mass coral bleaching or die-off is mounting.  

When ocean temperatures become too warm, corals expel the algae that they rely on for their energy needs in a stress response that leads to coral bleaching and, ultimately, coral death.

In the past, cyclones, heavy rain and other similar weather events have subdued the threat of a mass coral bleaching, however David said that meteorologists are not predicting any such weather event. 

Unprecedented back-to-back coral bleaching episodes in 2016 and ’17, triggered by record-breaking warm sea temperatures due to global heating, severely damaged two-thirds of the reef. Recovery since then has been slow and patchy.

Climate scientist Lesley Hughes from Macquarie University in Sydney explained that the closer together the bleaching events occur, the less time the coral has to recover.

“The bleaching event has killed a lot of coral so clearly there is simply less coral there now and less coral to reproduce and to replenish.

“The coral that did survive is likely to have a reduced capacity to reproduce and may be subject to disease and other stresses. If we get another bleaching event the ability to recover will be reduced even further.”

If this level of bleaching continues, a breakdown of the Great Barrier Reef coral reef system may take place. “It could become dominated by algae,” said Lesley. This would significantly affect the availability of habitat for species that rely on the coral reefs – there would be something there, but people may not wish to snorkel in it.

Terry Hughes, the director of the ARC Centre of Excellence for Coral Reef Studies, said we can no longer “ignore the elephant in the room”.

“The Australian government still supports expanding production of fossil fuels, even as the IPCC points to the urgent need to reduce global emissions to zero as soon as possible.

“We can’t ignore the elephant in the room and pretend we can climate-proof the reef with fans, floating sunscreen or by planting small patches of corals. The only way to reduce future temperature rises is to stop emitting greenhouse gasses.”