In a shocking report, the Australian Institute of Marine Science (AIMS) has revealed that parts of the Great Barrier Reef have undergone the most significant annual coral cover loss since records began nearly four decades ago. The northern and southern sections of the reef have both experienced widespread coral bleaching, attributed largely to climbing ocean temperatures linked to climate change, even as tropical cyclones and crown-of-thorns starfish outbreaks have contributed to the crisis.
The AIMS assessment spanned 124 coral reefs between August 2024 and May 2025, marking a stark warning that the habitat might reach a tipping point where recovery may not be feasible after catastrophic events. The Great Barrier Reef, renowned as one of the world’s largest living structures, stretches over 2,300 kilometers (1,429 miles) and supports an extraordinary diversity of marine life. However, repeated bleaching events are transforming large expanses of once-vibrant coral into stark white skeletons.
In a similar occurrence, Ningaloo, the country's second-largest reef located on the western coast, has also faced severe bleaching, with both major reefs turning white simultaneously for the first time. Coral plays an essential role in marine ecosystems, providing habitat for roughly 25% of all marine species. The bleaching phenomenon occurs when corals undergo stress from elevated water temperatures, causing them to expel their colorful symbiotic algae and turn white.
While coral can recover from heat-induced stress, it requires a sufficient recovery time, ideally spanning several years. The report indicates unprecedented levels of heat stress in 2024 and early 2025, marking the sixth major bleaching event since 2016. According to AIMS, the most impacted species are the Acropora, known for their rapid growth but also their vulnerability, especially since they are a preferred food source for the voracious crown-of-thorns starfish.
Efforts to control the culling of these starfish have seen some success, with over 50,000 of them eliminated by injecting them with vinegar or ox bile. However, experts like Richard Leck from the WWF emphasize that the reef remains under severe strain and caution against complacency. He notes that some reefs globally may be irreversibly damaged, suggesting without immediate climate action, the Great Barrier Reef could face a similar fate. Although designated as a UNESCO World Heritage site over 40 years ago, warnings proliferate that this natural wonder is "in danger" from rising sea temperatures and pollution.
