Coral bleaching (mass mortality)

Coral bleaching happens when corals lose the colorful algae living in their tissues because the water gets too warm. This process leaves the coral bone-white and starving. I saw this happen clearly in the northern parts of Komodo during the 2016 heatwave. It affects entire reef systems rather than just single colonies. High sea temperatures above 30°C for several weeks usually trigger these events. While a bleached coral is not dead immediately, it will die if the stress lasts too long.

Watch your buoyancy near stressed reefs. Divers often accidentally kick weakened structures because they are trying to find macro life in the rubble. Avoid touching any white patches you see. Even a light brush can kill a colony that is already struggling to survive.