Parts of Australia's Great Barrier Reef have suffered the highest coral die-off on record, and scientists fear the rest of the ecosystem will suffer the same fate, according to an Australian Institute of Marine Science study released 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 the hard corals have died, which constitutes the “largest annual decline” since the government began monitoring this 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 mass bleaching in eight years
The dieback phenomenon is caused by an increase in water temperature, which causes the expulsion of the symbiotic algae that 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, theAcroporais 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 resiliencehe 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.
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