Bleached and dead coral near Lizard Island, on the Great Barrier Reef, on April 5, 2024. DAVID GRAY / AFP Parts of the Great Barrier Reef in Australia have suffered the highest coral mortality ever recorded, and scientists fear that the rest of the ecosystem will suffer the same fate, according to a study by the Australian Institute of Marine Science published Tuesday, November 19. Carried out on twelve reefs, it reveals mortality of up to 72% due to massive bleaching this summer and two cyclones. In one area north of the Great Reef, about a third of hard corals have died, marking the “largest annual decline” since the government began monitoring the phenomenon thirty-nine years ago. The Great Barrier Reef, which stretches 2,300 kilometers 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. Five episodes of massive bleaching in eight years The phenomenon of dieback is caused by an increase in water temperature, which leads to the expulsion of the symbiotic algae which give the coral its bright color. If high temperatures persist, it turns white and dies. Five episodes of mass bleaching have been recorded in the Great Barrier Reef in eight years. The study published Tuesday specifies that a fast-growing coral, Acropora, is the one which 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 specified that the area which was the subject of the study is “relatively small” and said he feared “similar levels of mortality” for the entire Great Barrier. Le Monde with AFP Reuse this content
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