1,000 Of 1,600 Individual Corals Tracked At World Heritage Ningaloo Reef Dead As Result Of Latest Marine Heatwave

Almost two out of three corals across popular tourism spots at the world heritage-listed Ningaloo reef died after an unprecedented marine heatwave hit the Western Australia region, scientists have said. The areas in Ningaloo’s northern lagoon had undergone a “profound ecological simplification” with coral species that were keystones to the habitat among those killed. The marine heatwave swept across the Western Australian coastline last summer and autumn, turning corals white from heat stress from Ningaloo to Ashmore reef 1,500km to the north-east.

When corals sit in unusually warm water for too long they separate from the algae that give them much of their colour and nutrients, leaving behind a translucent flesh revealing the white skeleton behind. About 90% of the extra heat on the planet has been taken up by the ocean. The heating is caused when greenhouse gases are released from burning fossil fuels and cutting down forests.

Coral scientist Zoe Richards, an associate professor at Curtin University, had in March surveyed 1,600 individual corals at eight sites spanning 40km when the bleaching event was peaking. “The bleaching was so confronting because it was so expansive,” she said. Other scientists who visited Ningaloo during the mass coral bleaching spoke of their shock at the extent of the heat and the suffering of the corals.

When Richards, who carried out the work in partnership with the Minderoo Exmouth Research Laboratory, returned with Curtin University researcher David Juszkiewicz at the end of October, about 1,000 of the 1,600 corals she had recorded had died. She said: “You go in hoping the corals you saw that were partially bleached might have recovered. Unfortunately the scale tipped to mortality. Most of the data is showing that any coral that bleached in March went on to die.”

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https://www.theguardian.com/environment/2025/nov/19/two-out-of-three-corals-in-world-heritage-listed-ningaloo-reef-are-dead