08/09/2026
Reef health update | September 2026 🪸
September is Biodiversity Month, highlighting the incredible diversity of life across the Great Barrier Reef, including more than 2,900 coral reefs, 1,625 fish species and 450+ species of hard coral. As spring arrives, humpback whales are heading south, dwarf minke whales are leaving northern Reef waters and fish spawning activity is increasing.
Sea surface temperatures remained close to long-term averages across the Marine Park during August.
El Niño is firmly established and expected to strengthen, with forecasts suggesting it could peak in late spring or early summer. While El Niño can bring warmer and drier conditions, local weather systems mean conditions will vary across the Reef.
The Reef Authority and Queensland Parks and Wildlife Service are monitoring H5 bird flu following two detections in southern Queensland. There are currently no detected cases in the Great Barrier Reef Marine Park.
Temperature
Sea surface temperatures remained close to average through August. Temperatures in the Northern region were around 0.1–0.3°C above average, while temperatures across the rest of the Marine Park were close to or slightly above long-term averages.
The Bureau of Meteorology forecasts temperatures to remain around these levels through September and October.
Rainfall
Rainfall during August was slightly above average across the Northern and Far Northern catchments, while the Central and Southern catchments received slightly below-average rainfall.
The Northern and Far Northern catchments are likely to receive more rainfall than usual in September. Higher rainfall can increase the amount of water, sediment and nutrients flowing from catchments into the Marine Park.
Reef health
Between 1 and 31 August, 449 Reef Health Impact Surveys were completed across 42 reefs in the Marine Park.
In the Northern region, 29 reefs were surveyed. Seven recorded low levels of coral bleaching, while 28 recorded low to moderate coral damage.
In the Central region, 10 reefs were surveyed. One recorded medium levels of coral bleaching and three recorded low levels of coral damage.
In the Southern region, three reefs were surveyed, with no coral bleaching or coral damage recorded.
No surveys were conducted in the Far Northern region during August.
Coral disease was recorded on 21 of the 42 reefs surveyed during the month.
Additional Eye on the Reef monitoring reported coral bleaching on 18 of 36 reefs surveyed across the Marine Park.
Crown-of-thorns starfish control
As of 30 August 2026, the Crown-of-thorns Starfish Control Program and Reef Joint Field Management Program response teams surveyed and, where required culled starfish on 47 reefs.
Of these reefs:
• Crown-of-thorns starfish are at sustainable levels on 9 reefs (19%).
• Active culling is underway on 28 reefs (60%) to suppress outbreaks and protect coral.
• Crown-of-thorns starfish have been detected on another 10 reefs (21%), which will be prioritised for management as operationally feasible.
The program uses a science-based prioritisation process to focus effort on reefs with high ecological and economic value, with the aim of maximizing coral protection.
Our response and ongoing work
The Reef Authority and Queensland Parks and Wildlife Service are working with government agencies through the Reef Joint Field Management Program to prepare for and respond to H5 bird flu. If you see multiple sick or dead birds or other animals, do not touch them. Report sightings to the Emergency Animal Disease Hotline on 1800 675 888 and clean footwear, clothing, vehicles and boats when moving between sites.
The Reef Authority continues to work with Traditional Owners, researchers, Tourism Reef Protection Initiative operators, rangers and other partners to monitor Reef condition and support informed management. Long-term monitoring, including 40 years of AIMS data, helps identify changes, assess management actions and target efforts where they are needed most.
Reef management remains focused on supporting Reef resilience, including protecting high-value reefs, controlling crown-of-thorns starfish, maintaining zoning compliance and promoting responsible use of the Marine Park.