What’s Happening?
The Australian Institute of Marine Science (AIMS) has confirmed a sharp decline in coral cover across all three regions of the Great Barrier Reef, from Cape York to Gladstone. The 2025 Long-Term Monitoring Program (LTMP) summary shows that the widespread coral bleaching event in 2024, driven by extreme heat stress, has had lasting impacts. Cyclones and outbreaks of crown-of-thorns starfish have added further pressure.
This is the largest annual drop in coral cover recorded in two of the three reef regions since AIMS began monitoring nearly four decades ago.
Why It Matters
The Great Barrier Reef is one of Queensland’s most important natural assets. It supports marine biodiversity, drives tourism, and underpins thousands of jobs and industries. This scale of coral loss raises concerns not only about the health of the reef itself but about the long-term sustainability of coastal communities that rely on it.
Corals play a central role in marine ecosystems. A drop in coral cover can trigger wider changes in reef health and the marine life it supports.
Local Impact
The southern region, stretching from Proserpine to Gladstone, recorded the most severe loss. Coral cover fell by almost a third, from 38.9 percent to 26.9 percent. This is the largest single-year drop ever seen in the south since the LTMP began.
It also marks the first time the southern reef has recorded substantial bleaching effects. The 2024 event left a lasting footprint, pushing coral levels near long-term averages after years of recovery and record highs.
By the Numbers
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Northern region (Cape York to Cooktown): Coral cover dropped by 25 percent, from 39.8 percent to 30 percent
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Central region (Cooktown to Proserpine): Coral cover declined by 13.9 percent, from 33.2 percent to 28.6 percent
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Southern region (Proserpine to Gladstone): Coral cover dropped by nearly 31 percent, from 38.9 percent to 26.9 percent
Zoom In
Researchers surveyed 124 reefs between August 2024 and May 2025. Most reefs (77) now have hard coral cover between 10 percent and 30 percent. Another 33 reefs have coral cover between 30 percent and 50 percent. Only two reefs recorded cover above 75 percent, and two fell below 10 percent.
Acropora corals, known for fast growth but high sensitivity to heat, cyclones, and predators like crown-of-thorns starfish, were among the most affected. These species were already identified as vulnerable and proved to be the hardest hit in 2024.
Zoom Out
The damage to Queensland’s reef is part of a wider national pattern. Professor Selina Stead, CEO of AIMS, confirmed that this was the fifth mass bleaching on the Great Barrier Reef since 2016, and the most widespread. For the first time, Western Australian reefs also recorded the worst heat stress on record.
“It’s the first time we’ve seen a single bleaching event affect almost all the coral reefs in Australia,” Professor Stead said.
The bleaching observed in 2024 and 2025 was the second time in a decade that the Great Barrier Reef faced mass bleaching two years in a row. Professor Stead warned that climate-driven events are becoming more frequent and more intense, adding pressure to already stressed reef systems.
“These results provide strong evidence that ocean warming, caused by climate change, continues to drive substantial and rapid impacts to Reef coral communities,” she said.
What to Look For Next?
Support for reef-dependent communities and tourism operators may be needed, especially in regions hit hardest by the bleaching. AIMS will continue reef surveys and research throughout the coming year to track changes and inform future action.
