Coral Bleaching Has Damaged Over One-Third Of Corals In Parts Of Great Barrier Reef

Experts from the ARC Centre of Excellence for Coral Reef Studies conducted comprehensive aerial and underwater surveys, which reveal that mass bleaching has damaged almost 35 percent of corals on the northern and central Great Barrier Reef.

Apart from climate change, the damage to the corals tends to vary even while moving from north to south along the reef.

Coral bleaching happens in abnormal environmental conditions, such as sea temperatures that rise due to climate change. They make corals lose their photosynthetic algae, making them turn white, or "bleached."

"We found on average, that 35 percent of the corals are now dead or dying on 84 reefs that we surveyed along the northern and central sections of the Great Barrier Reef, between Townsville and Papua New Guinea," said Terry Hughes of the ARC Centre of Excellence for Coral Reef Studies and James Cook University (JCU), who participated in the research. "Some reefs are in much better shape, especially from Cairns southwards, where the average mortality is estimated at only 5 percent.

"This year is the third time in 18 years that the Great Barrier Reef has experienced mass bleaching due to global warming, and the current event is much more extreme than we've measured before," he added. "These three events have all occurred while global temperatures have risen by just one degree Celsius above the pre-industrial period. We're rapidly running out of time to reduce greenhouse gas emissions."

By recolonizing these algae or with reduced temperatures, they may recover. Otherwise, they might die.

"Fortunately, on reefs south of Cairns, our underwater surveys are also revealing that more than 95 percent of the corals have survived, and we expect these more mildly bleached corals to regain their normal color over the next few months," said  Mia Hoogenboom, also from JCU.

The team hopes that by revisiting the reefs that have been studied in order to find out the final measure of loss caused by bleaching, the team believes that it is possible to make them recover. However, it is expected to take a long time.