Reef health update | 9 April 2026

Sea surface temperatures continued to cool this week, dropping by 0.2–0.4°C across most of the Marine Park.

Tropical Cyclone Maila (37U) has now formed in the Solomon Sea and has rapidly intensified into a Category 5 system. Current Bureau of Meteorology forecasts show the system tracking into the Coral Sea, with a likely coastal crossing near Cape York Peninsula this weekend or early next week. Maila is expected to bring localised heavy rainfall, increasing the risk of flood plumes in the Marine Park and possible damage to coral and seagrass habitats from strong waves.

Encouragingly, coral bleaching alert levels have eased. The USA’s National Oceanic and Atmospheric Administration (NOAA), which monitors ocean temperatures globally, has downgraded the Northern, Central, and Southern regions to no stress conditions, following further drops in sea surface temperatures - reflecting heat stress easing across the Marine Park.

Temperature

Despite recent decreases in sea surface temperatures, they remain around 0.6–0.7°C above the long-term April average. The Far Northern and Northern regions are still experiencing the effects of accumulated marine heatwave exposure from earlier in summer, which may cause bleaching in some coral species.

Rainfall

Weekly rainfall across most catchments was average or below average, with totals generally under 100mm except for the Wet Tropics region receiving up to 150mm.

Rainfall in March was higher than usual across most Marine Park catchments, with the Cape York, Fitzroy and Burnett–Mary catchments having some of the highest March rainfalls recorded.

Reef health

Over the past week, 19 Reef Health Impact Surveys were completed across five reefs in the Marine Park.

In the Northern region, four reefs were surveyed with high (31–60%) to very high (61–90%) coral bleaching recorded on three reefs. These bleaching patterns in the Northern region are likely linked to heat stress accumulated over the summer combined with earlier flood plume impacts. All four reefs surveyed in the Northern region also showed severe coral damage, likely caused by storm impacts associated with Ex-Tropical Cyclone Narelle.

Limited surveys in the Far Northern region mean the full extent of coral bleaching is still emerging, but higher levels are expected given its prolonged exposure to above-average sea surface temperatures.

In the Central region, one reef was surveyed and no bleaching was recorded.

Additional Eye on the Reef observations from across the Marine Park reported bleaching on 11 of 19 reefs. No coral disease was recorded during the period.

Crown-of-thorns starfish control

As of 31 March 2026, the Crown-of-Thorns Starfish Control Program and Reef Joint Field Management Program response teams have surveyed and, where needed, culled starfish on 187 reefs this financial year.

Of these reefs:

Crown-of-thorns starfish are at sustainable levels on 80 reefs (43%).

Active culling is underway on 60 reefs (32%) to suppress outbreaks.

Starfish have been detected on 47 reefs (25%), and these reefs will be targeted for culling based on priority and actioned when 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 maximising coral protection.