Abstract
Quantitatively assessing mortality post coral bleaching at scale is inherently difficult, yet can be achieved with georeferenced imagery from aerial drones. Here, we assess the coral bleaching mortality rate from the 2024 global bleaching event at the iconic Lizard Island, Australia. Using drone-derived orthomosaics of the northern and southern sides of the island collected during and after the bleaching event, we measured the area of bleached coral and the area of live coral remaining after bleaching. Across twenty 10 × 10 m quadrats, mean bleaching mortality was 92.2 ± 6.8%, with bleaching affecting 96.92 ± 2.03% SD of living coral cover (mean, SD) of quadrat areas. This is one of the highest rates of bleaching mortality ever recorded, despite corals at Lizard Island being exposed to lower levels of cumulative heat stress than others in many parts of the Great Barrier Reef during this bleaching event.