Reef health update | 22 January 2026

Heavy rainfall over the past few weeks has led to flood plumes flowing into the Marine Park in the Northern, Central and Southern regions. These plumes are being closely monitored, with water quality checks underway through the Marine Monitoring Program.

Temperature

Sea surface temperatures have eased in some areas this week. The Far Northern region cooled by about 0.4°C, the Northern region stayed steady and the Central and Southern regions warmed slightly by 0.2–0.3°C. Temperatures across all regions are now close to the long-term average for this time of year

With cooler temperatures in the Far Northern region, heat stress has eased and reefs here have returned to a bleaching watch status.

Rainfall

Between 12 and 18 January, very heavy rainfall continued in the Mackay–Whitsunday and Fitzroy catchments following the tropical low linked to ex-tropical cyclone Koji. Some rainfall stations recorded more than 300 mm, with parts of the Mackay–Whitsunday region receiving over 500 mm.

Reef health

From 12 – 18 January, 124 Reef Health Impact Surveys were completed across 19 reefs in the Northern, Central and Southern regions. Low to medium levels of coral bleaching were recorded on nine reefs. At one reef in the Northern region, a small number of coral colonies were fully bleached, with very low levels of recent coral mortality observed.

Additional Eye on the Reef reports also noted coral bleaching on 11 reefs across all three regions. Some low to medium bleaching has been seen at offshore reefs in the Southern region, likely linked to short periods of heat stress earlier in January.

Flood plumes from the Wet Tropics and Mackay–Whitsunday catchments have moved into parts of the Marine Park. These plumes, which carry fresh water and sediment, may have contributed to bleaching and coral stress on some inshore reefs. Flood plumes from the Fitzroy catchment may develop in coming weeks and are being monitored.

Crown-of-thorns starfish control

Crown-of-thorns starfish (COTS) continue to affect reefs across the Marine Park. The most severe outbreaks remain in the Southern region (Swain Reefs) and in the Northern region between Cairns and Lizard Island. Since December, surveillance and control activities have been carried out on 128 reefs. Around one-third of these reefs now have COTS at levels that allow coral to recover, while active control is underway on about half of the reefs to reduce impacts.

Our response and ongoing work

Climate change remains the greatest threat to the Great Barrier Reef and addressing it requires urgent global action alongside strong local and regional management to build Reef resilience.

As Reef managers, the Reef Authority continues to work closely with the Reef Joint Field Management Program, the COTS Control Program, researchers, tourism operators and other partners to ensure decisions are based on the latest available data.

Every day, field officers are monitoring conditions, undertaking conservation actions on reefs and islands, and ensuring people are following the rules designed to protect the Reef.

Our work focuses on strengthening the Reef’s long-term resilience through:

managing crown-of-thorns starfish

enforcing compliance with the Reef’s zoning plan

supporting responsible tourism and recreation

collecting, analysing and sharing up-to-date Reef health information.

To inform our management, the Marine Monitoring Program and partners are currently in the field monitoring water quality and flood plumes across Cape York, the Wet Tropics, Burdekin, Fitzroy and Mackay–Whitsunday catchments.

We are also adapting management approaches to respond to a changing climate and other pressures, including supporting reef rehabilitation efforts and targeted regional actions to maintain ecosystem function.