Until now, many of Western Australia’s most pristine coral reefs have avoided the worst bleaching brought by marine heatwaves. But their luck has now run out. The state’s longest lasting, largest and most intense underwater heatwave has hammered them.
The unusual heat began late last year off the northwest coast, before spreading south, eventually affecting seas along more than 1,500km of coastline. Surface temperatures hit up to 4°C above average in places.
For coral, sustained heat stress is measured using degree heating weeks (DHW). At 4 DHW, coral bleaching is likely. At 8 DHW, many corals are at risk of bleaching and dying.
