Great Barrier Reef Severely Damaged By Coral Bleaching

Coral in Australia’s Great Barrier Reef has suffered a dramatic 89% decline from climate change-triggering bleaching events that took place in 2016 and 2017.  

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In a study published by Nature, scientists from James Cook University indicate that the future of the world-renowned reef is under threat as evidenced by the devastating effect of the climatic events on the ability of the corals to replenish.

“We’ve told the story of coral dying, we’ve told the story of some being winners and losers. Now we’ve got the next phase where species have a chance to recover,” Terry Hughes, the lead scientist in the study, stated.

Bleaching occurs when warmer temperatures cause the corals to expel photosynthetic algae which result in the organisms losing their color and nutrients, EcoWatch reported.

Hughes, who is director of the ARC Centre of Excellence for Coral Reef Studies at James Cook University said: “Fever babies means recovery will be slower, and the shift in species means the reefs will not recover to the same configuration as before. The question is, will that recovery be interrupted by another mass coral bleaching event due to escalating global warming?”

Coral reefs comprise less than 1% of the Earth’s marine environment but are home to an estimated 25% of ocean life.

Reefs are nurseries for many species of fish and a habitat for birds, sharks, dolphins and porpoises. The population of a particular branching coral, Acropora, which supports numerous marine species has plummeted by 93%.

“We never thought we would see disturbance on a scale to affect recruitment to this extent,” Andrew Baird, co-author of the study, added.

To analyze the extent of the devastation to the 2,300-kilometer reef, located off the coast of Queensland, the group of scientists tallied the volume of corals which survived the 2017 bleaching event as well as the number of new corals which sprung up the following year.

“Dead corals don’t make babies,” Hughes said.

The finding shows that the types of new coral being produced are different and the overall number of corals are extremely low compared to historical counts.

The growth of new corals had slowed to 2% in the gravely affected areas of the world’s largest reef system but has since doubled to 4%.

“We’ve always anticipated that climate change would shift the mix of coral,” Hughes said, but noting that “what’s surprised us is how quickly that is now happening. It’s not happening in the future. It’s something that we’re now measuring.”

The scientists have expressed doubt regarding the reef’s ability to fully recover if another bleaching event takes place within a decade. The rate at which the oceans are warming, the group explains, suggests that the Great Barrier Reef will require a lengthy uneventful recovery period or eventually cease to exist.

“It’s highly unlikely that we could escape a fifth or sixth (bleaching) event in the coming decade,” study co-author Morgan Pratchett said. “We used to think that the Great Barrier Reef was too big to fail — until now."