The Great Barrier Reef is alive and under serious pressure. After sharp coral losses following the 2024 marine heatwave, AIMS found early recovery or relative stability in regional coral cover in 2025–26. That recovery varied between reefs. Repeated marine heatwaves can kill corals faster than surviving colonies and new recruits can rebuild reef communities.
What the latest surveys found
The Australian Institute of Marine Science (AIMS) surveyed 121 reefs from August 2025 to June 2026. Coral cover increased at 28% of surveyed reefs, was stable at 56% and declined at 16%. Regional averages show that the north gained cover after the previous year’s drop. AIMS described the central and southern changes as within the uncertainty of the estimates. All three regional estimates remained below their 2023–24 levels. AIMS 2025–26 annual report · AIMS 2024–25 results
| AIMS monitoring region | 2023–24 | 2024–25 | 2025–26 |
|---|---|---|---|
| Northern | 39.8% | 30.0% | 35.1% |
| Central | 33.2% | 28.6% | 31.6% |
| Southern | 38.9% | 26.9% | 26.4% |
The Reef Authority’s November 2026 update reported above-average sea surface temperatures across all Marine Park regions. October surveys recorded low bleaching at some of the reefs visited, with no surveys in the Far Northern region that month. The update is a more recent snapshot of observed conditions. The annual AIMS report provides the comparable regional estimates above. Reef Authority monthly updates
How to read the numbers
Live hard coral cover estimates the share of surveyed reef surface covered by living hard coral. It can rise quickly when fast-growing branching or plate corals return. Coral diversity, the age of colonies and the three-dimensional habitat available to fish can take longer to recover. A regional estimate averages across reefs and can conceal losses at a particular snorkel site. AIMS monitoring methodology and coral composition
Bleaching prevalence measures how much coral looks bleached during a survey. A bleached colony can survive if conditions improve. Aerial surveys can reveal the footprint of bleaching in shallow water, while follow-up in-water surveys can show mortality and subsequent growth. For a worked example, read the 2024 aerial survey report and the coral bleaching guide.
What a percentage change means. The northern estimate moved from 30.0% to 35.1%, an increase of 5.1 percentage points, or about 17% relative to its starting value. The choice of unit makes a large difference to how a headline reads. The survey also has limits in time and space. Most northern sites in the 2025–26 programme were surveyed before Cyclone Narelle, so the annual results only partly capture the storm’s effects. AIMS annual estimates and cyclone survey coverage
What is damaging the Reef
Marine heatwaves and ocean warming. Heat stress is the main driver of mass bleaching. Higher baseline temperatures increase the chance of sustained heat, and ocean acidification can make it harder to build and maintain carbonate skeletons.
Cyclones and flood plumes. Waves can break corals and strip reef surfaces. Floodwater can expose inshore reefs to low salinity, sediment and nutrients. The severity varies with storm tracks, catchments and reef position.
Crown-of-thorns outbreaks. High numbers of this native predator can remove live coral, including colonies that survived an earlier disturbance.
Pressures near the coast. Poor water quality, habitat disturbance and some direct uses can compound damage. The Reef Authority’s 2024 Outlook Report identifies climate change as the greatest threat and also considers coastal development, land-based runoff and direct human use. Reef Authority Outlook Report · AIMS annual monitoring
Can it recover?
Recovery can start when surviving corals regain energy and grow, or when larvae from local and connected reefs settle and establish. The 2025–26 field season illustrates how relief from heat stress can give parts of the Reef a recovery window. A single better year tells us that recovery remains possible. Its durability depends on how often severe disturbances recur and whether enough colonies survive to replenish reefs. AIMS 2025–26 report · Reef Authority Outlook Report
How adult losses can slow the next generation. After the 2016 and 2017 mass bleaching events, researchers found 89% fewer new coral recruits in 2018 than in historical surveys. The study linked that drop to the loss of breeding adults and also found a shift in the mix of young corals. Repeated bleaching can therefore change which corals return as well as how quickly cover rebuilds. Hughes and colleagues’ coral recruitment study
Is it still worth visiting?
Yes. Individual reefs can still offer rich coral habitat and abundant marine life. Ask your operator which reef sites it expects to visit, when the crew last surveyed them and how it selects alternatives in changing conditions. Check the date on reef health updates and use regional data for context. Great Barrier Reef snorkelling guide · Reef Authority updates