Keystone-SDA
Parts of Australia’s Great Barrier Reef have suffered the highest coral mortality ever recorded, and scientists fear the rest of the ecosystem could suffer the same fate, according to a study published Tuesday.
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November 19, 2024 – 08:00
(Keystone-ATS) This study by the Australian Institute of Marine Sciences carried out on 12 reefs reveals mortality of up to 72%, due to massive bleaching this summer and two cyclones.
In one area of the northern Great Barrier Reef, around a third of hard corals have died, marking the “largest annual decline” since the government began monitoring the phenomenon 39 years ago.
The Great Barrier Reef, which stretches 2,300 km along the coast of the state of Queensland (northeast Australia), is considered the largest living structure in the world. It is home to extremely rich biodiversity, with more than 600 species of coral and 1,625 species of fish.
But several episodes of mass bleaching have transformed once thriving, multi-colored coral beds into pale, sickly expanses.
The phenomenon of coral dieback, which results in discoloration, is caused by an increase in water temperature which results in the expulsion of the symbiotic algae giving it its bright color. If high temperatures persist, the coral turns white and dies.
Limit to resilience
Five episodes of mass bleaching have been recorded in the Great Barrier Reef in eight years.
The study published Tuesday also indicates that a fast-growing coral, acropora, is the one that suffered the highest mortality rate.
The head of oceans at the NGO WWF-Australia, Richard Leck, said the latest data confirms his “worst fears”.
“The Great Barrier Reef can bounce back, but there are limits to its resilience,” he said. “She can’t be hit repeatedly like that. We are rapidly approaching a tipping point.”
Mr. Leck stressed that the area studied is “relatively small” and said he feared “similar levels of mortality” across the Great Barrier Reef.
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