The colour of massive corals is not linked to the thermal sensitivity of photoendosymbiosis on Norfolk Island’s subtropical coral reefs

Context Approximately half of scleractinian corals rely on endosymbiotic Symbiodiniaceae, making them vulnerable to bleaching during thermal stress. Accurately interpreting bleaching responses is essential for monitoring reef health, yet visual assessments of coral colour often overlook symbiotic status or physiological health. Aims This study aimed to determine whether coral colour is a reliable indicator of symbiosis or bleaching response in massive coral genera Platygyra and Paragoniastrea in