The 2024/25 marine heatwave that brought heat stress to coral reefs off the Western Australian coast was the longest, largest and most intense on record for the state, resulting in the most widespread coral bleaching event ever recorded for WA, scientists and managers say.

While the full impact of the coral bleaching will take months to be known, experts from multiple organisations and agencies which make up the WA Coral Bleaching Group have so far reported bleaching and mortality ranging from medium (11%-30%) to extreme (>90%) levels across systems up to 1500km apart as a result of the marine heatwave. A newsletter summarising the event has been released today by the Group, available here.