In Western Australia, Up To 90% Of Corals Bleached Or Dead Across 900-Mile Stretch Of Reefs

The “longest, largest and most intense” marine heatwave ever recorded in Western Australia has killed coral throughout an area that stretches 1,500km, according to state and federal scientists. More than 100 scientists and marine managers will gather in Perth on Tuesday for a special meeting to discuss the devastating event that bleached and killed corals on remote reefs earlier this year.

The marine heatwave that hit reefs from the World Heritage-listed Ningaloo to the remote Ashmore Reef left many scientists shocked. A group of scientists from state and federal government departments, agencies and universities, who monitor coral bleaching in Western Australia, will issue a detailed update on Tuesday.

The heatwave, which started to build off the north-western WA coast in August 2024, caused heat stress in corals across the state’s northern reefs that lasted until May this year in “the most severe coral bleaching on record for Western Australian coral reefs,” the update said.

Dr James Gilmour, a senior research scientist at the Australian Institute of Marine Science that coordinates the monitoring group, said on some coral reefs that were inspected, more than 90% of corals had either bleached or died. “When you have more than about 75% of corals that have bleached or died, it can be very hard to find any healthy corals,” he said. The update from the WA Coral Bleaching Group said the amount of bleaching and coral death on reefs ranged from medium (11%- 30%) to extreme (greater than 90%) across systems up to 1,500km apart.

EDIT

https://www.theguardian.com/australia-news/2025/aug/12/was-longest-and-most-intense-marine-heatwave-killed-coral-across-1500km-stretch