A new research published in the journal Coral Reefs (Springer Nature) has revealed one of the highest coral mortality rates ever recorded worldwide: 92% of the bleached corals on Lizard Island, part of the Australian Great Barrier Reef, died after the fourth global bleaching event declared by NOAA in April 2024.
The study was led by Dr. Vincent Raoult (Griffith University) and Professor Jane Williamson (Macquarie University), with the participation of James Cook University, CSIRO, and the geospatial data platform GeoNadir.
Aerial Technology and Alarming Diagnostics
Researchers used high-resolution drone images to map 20 sections of 10 × 10 meters on the north and south reefs of Lizard Island. Observations were made in March, during the peak of bleaching, and repeated in June to quantify mortality.
Results:
- 96% of the live corals were affected by bleaching
- 92% of those corals died a few months later
- The island experienced extremely high mortality, despite having recorded lower thermal stress than other reef regions
“These data reflect the extreme vulnerability of corals even to moderate thermal increases,” stated Dr. Raoult. “It is a clear sign that coral ecosystems are losing their resilience to climate change”.
Coral Resilience in Check
According to Professor Williamson, the study highlights the rapid degradation of coral resilience to the increasing events of extreme heat, which are becoming more frequent and intense.
The use of drones allowed scaling measurements with high precision, providing a broad yet detailed view of the bleaching impact.
Endangered Ecosystems and Political Urgency
The Great Barrier Reef —declared a World Heritage Site by UNESCO— is one of the most biodiverse marine ecosystems on the planet. However, it has been facing a systematic decline for decades, driven by:
- Ocean warming
- Water acidification
- Extreme weather events
- Contamination and anthropogenic pressure
The authors emphasize that this new data should accelerate international climate action, not only to reduce greenhouse gas emissions, but also to strengthen the active protection of coastal ecosystems worldwide.
