Scientists have started monitoring remote reefs off the coast of Queensland to see if they have survived back-to-back bleaching events.
The 25-day health check is being undertaken by the Australian Institute of Marine Science with federal funding through the Great Barrier Reef Foundation (GBRF).
It will provide a baseline assessment of reef conditions and recovery in sections of the reef that have not been surveyed since late 2016.
"We don't currently know the extent of coral loss attributable to the latest bleaching in 2017 or of any other disturbances that have occurred in that time," GBRF managing director Anna Marsden said.
Scientists will survey more than 20 reefs off Cape York between Cooktown to north of Cape Grenville.
They will be assessing signs of recovery in young coral, and identifying whether surviving corals had developed an increased tolerance to warmer waters.
They will also be collecting data on crown of thorns starfish.
Australian Associated Press