Sea surface temperatures continue to ease across the Marine Park this week, dropping by around 0.1–0.2°C.

Heavy rainfall from ex-Tropical Cyclone Narelle caused a major flood in the Far Northern region, with the Pascoe River reaching 19.3 metres - the highest level recorded in more than 50 years and likely a one-in-200-year event. The flood plume may affect nearby ecosystems like seagrass meadows and inshore reefs by lowering salinity and increasing exposure to sediments, nutrients, and pesticides.

The Bureau of Meteorology forecasts a tropical low (37U) may form near the Solomon Islands by Thursday, with a moderate to high chance of developing into a cyclone over the weekend. At this stage, it is expected to stay away from the Queensland coast over the next week.

Temperature

Despite recent decreases in sea surface temperatures, they remain around 0.7°C above the long-term monthly 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 corals species.

Rainfall

Weekly rainfall totals were mostly average or below average across the Marine Park catchment areas during the past week, with up to 100mm of rain recorded over the reporting period.

Reef health

Over the past week, 43 Reef Health Impact Surveys were conducted across seven reefs in the Marine Park. In the Northern region, five reefs were surveyed with coral bleaching ranging from low (1–10%) to very high (61–90%). In the Central region, two reefs were surveyed and no coral bleaching was observed.

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.

Additional Eye on the Reef observations from across the Marine Park reported bleaching on 9 out of 24 reefs.

High levels of bleaching in the Northern region may be linked to prolonged heat exposure and impacts from flood plumes. Surveys also recorded moderate to extreme coral damage on three Northern reefs, likely from storm impacts related to Ex-Tropical Cyclone Narelle. One Central reef showed low damage from storms activity, and one reef had moderate coral disease.

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.