'Dead corals don’t make babies': New study raises serious concerns about the Great Barrier Reef

  • Global warming is severely compromising the ability of the Great Barrier Reef’s corals to recover.
  • There was nearly a 90% fall in new coral growth last year, according to a study published in Nature on Wednesday.
  • The Great Barrier Reef is the world’s largest living structure but scientists are now concerned it could fail.

In a disturbing new study, it has been revealed that global warming is having a major impact on new coral growth along the Great Barrier Reef.

The study — published in Nature on Wednesday and titled “Global warming impairs stock–recruitment dynamics of corals” — raises fresh concerns about the health of the world’s largest reef, which runs for 2,300km along the east coast of Australia.

“Dead corals don’t make babies,” said lead author Professor Terry Hughes, director of the ARC Centre of Excellence for Coral Reef Studies at James Cook University (JCU). “The number of new corals settling on the Great Barrier Reef declined by 89% following the unprecedented loss of adult corals from global warming in 2016 and 2017.”

Hughes and his team of scientists counted how many adult corals survived along the Great Barrier Reef following high temperatures, and assessed the number of new corals they produced to replenish the reef in 2018.

The decline in the number of adult corals over 2016 and 2017, when global warming led to higher temperatures and mass bleaching, meant there were fewer baby corals introduced to the reef in 2018 compared to previous years.

Photo: Airbnb/ supplied.

“The number of coral larvae that are produced each year, and where they travel to before settling on a reef, are vital components of the resilience of the Great Barrier Reef. Our study shows that reef resilience is now severely compromised by global warming,” said co-author Professor Andrew Baird.

“The biggest decline in replenishment, a 93% drop compared to previous years, occurred in the dominant branching and table coral, Acropora. As adults these corals provide most of the three-dimensional coral habitat that support thousands of other species,” he said.

It could take up to a decade for the reef to recover from the mass bleaching seen in 2016 and 2017. Hughes said surviving corals will grow and more of them will reach sexual maturity, assuming there isn’t another mass bleaching event.

In total, the Great Barrier Reef has seen four mass bleaching events over the last 21 years. They took place in 1998, 2002, and back-to-back in 2016 and 2017. But scientists are worried that the gap between pairs of coral bleaching events will continue to shrink as global warming intensifies.

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

Hughes said the only way to fix the problem is to address the root cause of global heating. That means reducing net greenhouse gas emissions to zero as quickly as possible.

The Great Barrier Reef supports 64,000 jobs and contributes $6.4 billion to the Australian economy, according to a Deloitte study into the economic, social and icon value of the reef.

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