This past summer, the corals on the Great Barrier Reef were exposed to the greatest heat stress ever recorded. In March, scientists declared the reef was experiencing its fifth mass bleaching event, part of a global mass coral bleaching event.

Corals can recover from bleaching, but scientists doing surveys on a reef near Lizard Island found nearly all the corals had died. To find out what that means for the reef more broadly, and for marine life, we speak to Professor Jane Williamson from Macquarie University.

Image: ARC Centre of Excellence for Coral Reef Studies.