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Reef Health Updates

Reef Health Updates

Written by: Great Barrier Reef Marine Park Authority
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As the lead managers of the Great Barrier Reef, the Reef Authority keeps an eye on the Reef year-round — with efforts stepped up over summer, a typically high-risk period from extreme weather.

The Reef Authority releases updates on the health of Reef which includes; sea surface temperatures, rainfall and floods, cyclones, crown-of-thorns starfish outbreaks, and coral disease.

These updates are based on forecasts, water temperature heat mapping, in-water surveys, citizen science and aerial surveys.

GBRMPA 2026
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Episodes
  • Reef health update | 7 May 2026
    May 7 2026

    Reef health update | 07 May 2026

    Sea surface temperatures continued to ease across the Marine Park this week.

    Queensland’s wet season has also come to an end, ranking as the 9th wettest on record since 1900, with most Marine Park catchments receiving above-average rainfall.

    Climate conditions remain neutral, however, sea surface temperatures in the Pacific Ocean (between the Tropic of Cancer and the Tropic of Capricorn) are warming. Current Bureau of Meteorology outlooks indicate a possible El Niño developing by late winter, which could bring drier conditions to Northern Queensland in the months ahead.

    Temperature

    Sea surface temperatures declined slightly, dropping by 0.3–0.6°C across the Marine Park.

    Over the coming month, temperatures are expected to sit close to average, although some offshore reefs in the Far Northern and Northern regions may remain slightly above average (up to 0.8°C).

    Rainfall

    With the start of the dry season, rainfall was below average across most catchments, with totals generally below 25mm. The Wet Tropics was the exception, receiving up to 150mm.

    Looking ahead, forecasts suggest a low chance of above-average rainfall across the Marine Park during May.

    Reef health

    Over the past week, 49 Reef Health Impact Surveys were conducted across six reefs.

    In the Northern region, five reefs were surveyed, with low to moderate coral bleaching recorded and low to moderate coral damage observed across all sites.

    In the Central region, one reef was surveyed with no bleaching and low coral damage.

    Coral disease was recorded on three reefs during this period.

    Additional Eye on the Reef monitoring reported coral bleaching on 11 of 14 reefs surveyed across the Marine Park.

    Crown-of-thorns starfish control

    As of 30 April 2026, the Crown-of-Thorns Starfish Control Program and Reef Joint Field Management Program response teams have surveyed and, where needed, culled starfish on 204 reefs this financial year.

    Of these reefs:

    • Crown-of-thorns starfish are at sustainable levels on 91 reefs (45%)
    • Active culling is underway on 67 reefs (33%) to suppress outbreaks
    • 47 reefs (25%) have COTS present and will be targeted based on priority and operational conditions

    The program uses a science-based prioritisation process to focus effort on reefs with high ecological and economic value, with the aim of maximising coral protection.

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    2 mins
  • Reef health update | 30 April 2026
    Apr 30 2026

    Reef health update | 30 April 2026

    Sea surface temperatures continue to ease across the Marine Park, and with the changing of seasons we are seeing the last of the turtle hatchlings and seabird nesting, as humpback and Minke whales begin arriving in the Reef’s breeding grounds.

    Queensland’s wet season is also coming to an end, with rainfall over the summer months among the highest levels recorded since 1900.

    Temperature

    Sea surface temperatures declined slightly, dropping by 0.3–0.5°C across the Marine Park, temperatures remain 0.4–0.5°C above the long-term April average.

    Rainfall

    Weekly rainfall totals were below average across most Marine Park catchments, with less than 50mm recorded.

    Reef health

    Over the past week, 43 Reef Health Impact Surveys were conducted across six reefs.

    In the Northern region, four reefs were surveyed. Two recorded low coral bleaching, and three showed low to moderate coral damage. Higher bleaching levels in the Northern region are likely linked to prolonged heat exposure over summer combined with earlier flood plume impacts. Coral damage in the Far Northern and Northern regions is likely the result of storm impacts from Ex-Tropical Cyclone Narelle.

    In the Central region, one reef was surveyed with no coral bleaching or damage recorded.

    In the Southern region, one reef was surveyed with no coral bleaching or damage recorded.

    No coral disease was observed over the past week.

    Additional Eye on the Reef observations from across the Marine Park reported coral bleaching on 16 of 20 reefs surveyed.

    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.

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    2 mins
  • Reef health update | 23 April 2026
    Apr 23 2026

    Reef health update | 23 April 2026

    Ex-Tropical Cyclone Maila crossed Cape York Peninsula as a tropical low on 15 April, bringing moderate rainfall of up to 50mm to coastal Cape York and Wet Tropics catchments.

    Sea surface temperatures continue to ease, and with the changing of seasons we are now seeing the first humpback whales arriving in the Marine Park, as they migrate from Antarctic waters to their traditional breeding grounds.

    A recent Reef Authority and Queensland Parks and Wildlife Service voyage in the Far Northern region completed 75 surveys across five reefs, providing early insights into cyclone impacts. Reefs closest to Ex-Tropical Cyclone Narelle’s path showed moderate to severe structural damage, while more sheltered reefs to the south of the cyclone’s path recorded low to minimal impacts. Damage was generally higher on reef areas exposed to incoming waves. The team also observed island vegetation damage, localised erosion, and coral colonies washed up on beaches or cays, along with low levels of coral bleaching on two reefs.

    Some planned sites could not be accessed due to weather conditions associated with Ex-Tropical Cyclone Maila; however, Crown-of-thorns starfish control teams are scheduled to return to these areas and are expected to access these sites and undertake surveys to improve our understanding of Reef health impacts.

    Temperature

    Sea surface temperatures declined slightly this week by around 0.1°C across the Marine Park. Temperatures remain 0.5–0.7°C above the long-term April average.

    Rainfall

    Weekly rainfall totals were average across most of the Marine Park catchments over the past week. Weekly totals reached up to 150mm in Cape York and the Wet Tropics, and up to 100mm in the Mackay–Whitsunday region.

    Reef health

    Over the past week, 225 Reef Health Impact Surveys were conducted across 22 reefs.

    In the Far Northern region, five reefs were surveyed. Two recorded low bleaching, and all showed low to severe coral damage.

    In the Northern region, five reefs were surveyed, with bleaching ranging from low to very high (up to 90%). Three reefs also recorded low to severe coral damage. Higher bleaching levels in the Northern region are likely linked to prolonged heat exposure over summer combined with earlier flood plume impacts. Coral damage in the Far Northern and Northern regions is likely the result of storm impacts from Ex-Tropical Cyclone Narelle.

    In the Central region, 11 reefs were surveyed. Eight showed low to moderate bleaching, and four recorded low coral damage.

    In the Southern region, one reef was surveyed, showing moderate bleaching and low coral damage.

    Coral disease was recorded on six reefs across the Marine Park.

    Additional Eye on the Reef observations from across the Marine Park reported coral bleaching on 12 of 17 reefs surveyed.

    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.

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    2 mins
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