Marine heatwave causes unprecedented regional mass bleaching of thermally resistant corals in northwestern Australia

A marine heatwave during the 2015/16 El Niño event caused unprecedented regional mass bleaching of thermally resistant corals in northwestern Australia, particularly affecting the Kimberley region where 4.5-9.3 degree heating weeks (DHW) led to 56.6-80.6% bleaching. This demonstrates that even heat-tolerant corals from naturally extreme environments are vulnerable to heatwaves. Coral health surveys were conducted across four bioregions, revealing significant bleaching in the Kimberley while Rottnest Island experienced minor impacts and Ningaloo Reef and Bremer Bay remained unaffected. The findings suggest that Western Australian reefs are now at risk during both El Niño and La Niña years, marking a shift from previous patterns where only strong La Niña events caused major bleaching.

Le Nohaïc, M., Ross, C. L., Cornwall, C. E., Comeau, S., Lowe, R., McCulloch, M. T., & Schoepf, V. (2017). Marine heatwave causes unprecedented regional mass bleaching of thermally resistant corals in northwestern Australia. Scientific Reports, 7(1). https://doi.org/10.1038/s41598-017-14794-y