Reef health update - 12 March 2026

Sea surface temperatures eased slightly across the Marine Park over the past week.

A tropical low crossed the Marine Park on 5–6 March. The system, together with a monsoon trough, brought heavy rainfall to the Cape York, Wet Tropics and Mackay–Whitsunday catchments. While this has helped keep temperatures down across the Reef, it also increases the likelihood of freshwater runoff entering the Marine Park.

Another tropical low (34U) is forecast to develop in the Coral Sea off the East Coast of North Queensland. Forecasts continue to be monitored for any potential impacts to the Reef.

Temperature

Over the past week sea surface temperatures dropped from around 30°C to 29.1°C in the Far Northern region following recent weather systems. Sea surface temperatures in other regions also declined slightly, by around 0.1–0.4°C.

Despite this, sea surface temperatures remain above the long-term average. The Far Northern, Central and Southern regions are currently around 0.7–0.9°C above average, while the Northern region remains around 1.3°C above average.

As a result, heat stress continues to build across parts of the Marine Park. Some reefs in the Far Northern and Northern regions are experiencing conditions that may lead to bleaching in heat-sensitive corals.

Rainfall

From 2–8 March, heavy rainfall fell across the Cape York, Wet Tropics and Mackay–Whitsunday catchments. Weekly totals reached 300–400mm in some areas, with several locations receiving more than 200mm in a single day. Overall, rainfall for March so far is above to well above average in these regions.

Heavy rainfall can increase the risk of freshwater runoff entering the Marine Park.

Reef health

Over the past week, 73 Reef Health Impact Surveys were completed across nine reefs in the Northern and Central regions.

Monitoring shows that coral bleaching impacts remain varied across the reefs surveyed.

Surveys on reefs in the Northern region recorded coral bleaching ranging from low levels (1–10%) to very high levels (61–90%). One reef in the Central region recorded medium bleaching levels (11–30%).

Two reefs in the Northern region recorded small areas of fully bleached coral (less than 5%) and low levels of recent coral mortality (less than 3%).

Coral damage was recorded on five reefs and coral disease was observed on four reefs.

Additional observations from the Eye on the Reef monitoring programs also reported coral bleaching on eight of the 13 reefs surveyed.

In the coming weeks, Reef Authority and Queensland Parks and Wildlife Service teams will carry out additional surveys in areas that have experienced high heat exposure to better understand impacts on reef health.

Crown-of-thorns starfish control

The Crown-of-thorns Starfish Control Program continues to manage ongoing outbreaks across the Marine Park, with updates shared in the first weekly Reef Health Update of each month.

Our response and ongoing work

Marine Monitoring Program teams and partners were also in the field sampling flood waters from the Annan and Endeavour rivers, with further sampling planned for the Normanby River in the coming week.

The Reef Authority’s management decisions are informed by data collected by our teams on the water, including the Reef Joint Field Management Program and Crown-of-thorns Starfish Control Program as well as the collaborative efforts of researchers, tourism operators, contractors and partners.

Management actions remain focused on supporting Reef resilience, including enforcing compliance with zoning rules and encouraging responsible use of the Marine Park.

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