New analysis of the Great Barrier Reef’s Lizard Island reveals a devastating coral mortality rate of 92 percent following the unprecedented 2024 global bleaching event, marking one of the most severe mass coral deaths ever recorded worldwide. This groundbreaking study, conducted by an interdisciplinary team from Griffith University, Macquarie University, James Cook University, CSIRO, and GeoNadir, draws attention to the escalating fragility of coral reef ecosystems under the mounting pressures of climate change.
The scientific team meticulously surveyed 20 distinct reef sections, each spanning 100 square meters, strategically distributed across both the northern and southern regions of Lizard Island. The assessments employed cutting-edge drone technology to capture high-resolution imagery during the bleaching peak in March 2024, with follow-up surveys in June confirming extensive coral mortality. These remote sensing techniques, validated through in-water observations, allowed for precise quantification of coral health over spatial scales rarely achieved in ecological monitoring.
Thermal stress analysis indicated that Lizard Island experienced approximately six degree Celsius-weeks of accumulated heat stress—a relatively moderate heat signature compared to other sectors of the Great Barrier Reef. Nevertheless, the resulting coral mortality rates surpassed all historical benchmarks documented at this site, suggesting a nonlinear and compounding impact of thermal events exacerbated by prior disturbances. This anomaly underscores the complex interplay between episodic heat stress and the reef’s cumulative ecological resilience.
The extent of coral bleaching was staggering, with 96 percent of living corals exhibiting visible bleaching signs during the event. Subsequent mortality culminated in an average reef-wide death rate of 92 percent, with localized mortality peaking beyond 99 percent in the most severely impacted zones. This mass die-off obliterates the foundation of the reef ecosystem, threatening the survival of countless associated marine species that depend on coral structures for habitat and food resources.
Disturbances preceding the recent bleaching event have left the Lizard Island reef system in a vulnerable state. The last decade has seen multiple stressors including compounded bleaching episodes in 2016 and 2017, destructive cyclonic activity, and outbreaks of the Crown-of-Thorns starfish—a notorious coral predator. These sequential stressors have eroded the reef’s capacity for natural recovery, amplifying its susceptibility to acute heatwave-induced bleaching.
Lead researcher Dr. Vincent Raoult emphasized that despite Lizard Island encountering less extreme heat stress relative to other parts of the Great Barrier Reef, the mortality rates observed were unprecedented. This discrepancy highlights the potential for sub-lethal disturbances and long-term ecosystem degradation to compound vulnerability, attenuating the reef’s ability to buffer and rebound from climate-induced stress.
Professor Jane Williamson, senior author from Macquarie University, highlighted the critical role of drone-derived imagery in delivering high-resolution, repeatable assessments across expansive and difficult-to-access reef areas. This technology not only provides a scalable approach to coral monitoring but also enhances precision, allowing researchers to discriminate between bleaching intensity, coral mortality, and post-event recovery trajectories with exceptional clarity.
The implications of such high mortality rates are profound. Coral reefs function as biodiversity hotspots, carbon sinks, and coastal buffers. The loss of more than 90 percent of coral cover at Lizard Island threatens to cascade through marine food webs, reduce fisheries productivity, and impair ecosystem services vital to millions of people. The long-term consequences for reef resilience remain uncertain, particularly given the accelerated frequency of heat stress events projected under climate change scenarios.
The research team plans to continue monitoring the affected reef sites through 2026 under an Australian Museum Lizard Island Critical Grant, aiming to track potential coral recovery or shifts in reef community composition. Understanding whether coral populations can regenerate or adapt post-disturbance is crucial to informing conservation strategies and management policies aiming to mitigate climate change impacts on coral reefs.
This study represents a clarion call to the global scientific and policy communities, underscoring the urgent need to intensify mitigation efforts to reduce greenhouse gas emissions and enhance reef resilience. Without immediate action, coral reef ecosystems may continue to face diminishing chances for survival in a warming ocean, jeopardizing biodiversity and human livelihoods supported by these fragile marine habitats.
In conclusion, the unprecedented coral mortality evidenced at Lizard Island following the 2024 global bleaching event provides a stark illustration of the escalating threats facing coral reefs worldwide. By leveraging advanced drone technology and multidisciplinary collaboration, the research unveils both the scale of ecosystem collapse and the inherent complexities driving reef degradation under climate change. The path forward demands integrated scientific, conservation, and policy responses to safeguard the remnants of these irreplaceable underwater worlds.
Subject of Research: Coral bleaching and mass mortality following the 2024 global bleaching event at Lizard Island, Great Barrier Reef
Article Title: Coral bleaching and mass mortality at Lizard Island revealed by drone imagery
News Publication Date: Not explicitly stated in the content
Web References:
https://link.springer.com/article/10.1007/s00338-025-02695-w
http://dx.doi.org/10.1007/s00338-025-02695-w
References: Not detailed in the provided content
Image Credits: Karen Joyce
Keywords: Coral bleaching, coral mortality, Great Barrier Reef, Lizard Island, climate change, drone imagery, thermal stress, reef resilience, marine ecosystems, global bleaching event
