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Tropical North Queensland Great Barrier Reef. https://www.tropicalnorthqueensland.org.au/great-barrier-reef-2/

Australia: Climate Change Disrupts Recovery of Great Barrier Reef

TOWNSVILLE, Queensland, Australia, April 13, 2019 (ENS) – The damage caused to the Great Barrier Reef by the warming climate has compromised the capacity of its corals to recover, finds new research published earlier this month in the journal “Nature.”

The unique study measured how many adult corals survived along the length of the world’s largest reef system following extreme heat stress, and how many new corals they produced to replenish the Great Barrier Reef in 2018.

corals

The color morphs of the coral Acropora millepora, each showing a different response during the mass coral bleaching event in 2017 offshore of Orpheus Island, Queensland, Australia.  (Photo by Gergely Torda / ARC Centre of Excellence for Coral Reef Studies)

The loss of adults resulted in a crash in coral replenishment compared to levels measured in the years before mass coral bleaching.

“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. “The number of new corals settling on the Great Barrier Reef declined by 89 percent following the unprecedented loss of adult corals from global warming in 2016 and 2017.”

To date, the Great Barrier Reef has experienced four mass bleaching events due to global warming, in 1998, 2002, and back-to-back in 2016 and 2017. Scientists predict that the gap between pairs of coral bleaching events will continue to shrink as global warming intensifies.

“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 percent 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.

“The mix of baby coral species has shifted, and that in turn will affect the future mix of adults, as a slower than normal recovery unfolds over the next decade or longer,” said Baird.

“The decline in coral recruitment matches the extent of mortality of the adult broodstock in different parts of the Reef,” said Hughes. “Areas that lost the most corals had the greatest declines in replenishment.”

“We expect coral recruitment will gradually recover over the next five to 10 years, as surviving corals grow and more of them reach sexual maturity, assuming of course that we don’t see another mass bleaching event in the coming decade,” he said.

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