Summer snapshot finds uneven pressures on Great Barrier Reef

The Great Barrier Reef weathered a mixed summer, with coral bleaching, cyclones and flooding affecting parts of the Marine Park while many reefs remain in good condition, according to a snapshot published today. The Reef snapshot: Summer 2025-26 reported prolonged heat exposure, cyclones and flood plumes across sections of the Marine Park, particularly in the Northern and Far Northern regions.

Reef Authority Chief Scientist Dr Roger Beeden said the season delivered a series of compounding pressures but that conditions varied widely along the 2,300km ecosystem. “The Great Barrier Reef is a vast and highly diverse ecosystem – with more than 3000 individual reefs stretching across an area the size of Japan – and conditions can differ dramatically from reef to reef,” he said.

The snapshot identifies a regional coral bleaching event in the Northern region, with localised low levels of bleaching in the Far Northern, Central and Southern regions. The bleaching in the Northern region became apparent in March 2026 after prolonged heat exposure over summer.

Dr Beeden noted that bleaching does not necessarily lead to coral mortality, adding, “That capacity to bounce back is one of the defining strengths of the Great Barrier Reef.” Severe Tropical Cyclone Narelle crossed the Far Northern region in March as a category 5 system, generating sustained high wave action for more than 24 hours.

Preliminary observations identified wave damage to coral reefs surveyed between Cairns and Lizard Island. Earlier in the season, Tropical Cyclone Koji crossed the Marine Park’s Central region in January, bringing heavy rainfall and river flood plumes. Crown-of-thorns starfish outbreaks persist across the Marine Park, with the most severe activity in the Northern and Southern regions.

The Reef Authority’s control program continues targeted surveillance and systematic culling to protect coral cover on high-value reefs. In response to the summer’s impacts, scientists, tourism operators, Traditional Owners and Reef managers are surveying affected sites, protecting high-value reefs and supporting recovery.

The Reef Authority and partners are focusing assessments on reefs and islands between Cooktown and Lockhart River, where damage from Severe Tropical Cyclone Narelle and prolonged heat exposure is expected to be highest.

To speed recovery at reefs impacted by Narelle, the Reef Authority issued a temporary management authorisation to about 875 tourism operators and Traditional Owners, allowing permit holders to “flip and re-attach” damaged coral for a month after the March 20 cyclone where quick action—such as turning over coral colonies and reattaching freshly broken fragments—can improve coral survival.

The Reef snapshot is a joint initiative of the Great Barrier Reef Marine Park Authority, the Australian Institute of Marine Science and CSIRO. Focusing solely on coral, it provides a point-in-time summary of environmental conditions and major disturbances from December 2025 to mid-March 2026.

The full extent of cumulative impacts, including results from a scientific voyage to far northern reefs, will be compiled into detailed reports to be released later in 2026.