Tropical cyclone Kirrily crossed the Great Barrier Reef Marine Park (Marine Park) as a category three system on Thursday 25 January 2024, making landfall as a category two.

Any potential impacts – from waves and flood plumes – to exposed reefs in the Marine Park will be assessed in the coming weeks as model outputs, observations and survey data becomes available.

Temperature
Increased cloud cover and rainfall in the northern region have cooled sea surface temperatures to near average.

In the central and southern regions, sea surface temperatures were ~1°C above average, with parts of the inner central region and southern region reaching ~1.5°C.

As sea surface temperatures exceed monthly averages, thermal stress is accumulating across the Marine Park, which may affect thermally sensitive coral species in shallow reef habitats.

Rainfall
The active monsoon trough, combined with the tropical low system, brought variable rainfall — from 15mm to 400 mm — to catchments connected to the Great Barrier Reef.

Rainfall from the active monsoon and ex-tropical cyclone Kirrily may cause reduced salinity of inshore areas, particularly between Cooktown and Bowen.

Any impacts from the rainfall entering the Reef will be monitored through surveys conducted as part of the Marine Monitoring Program.

Reef health
Of the 170 surveys conducted in the Marine Park between 24-31 January 2024, most recorded none to minor impacts of coral bleaching, disease, and damage.

Within in the Marine Park, the highest known outbreak density of crown-of-thorns starfish continues at some reefs in the outer southern region.

A severe, isolated outbreak remains on a couple of reefs offshore Townsville and the Whitsundays in the central region.

Reef management
The Reef Authority continues to monitor conditions on the Reef – planning, preparing, and responding accordingly to any events over the high-risk summer period.

If you are out in the Marine Park, you can report what you see through the Eye on the Reef app, and make sure you know your zones to help do your bit in protecting this World Heritage-listed natural wonder.

Sick, injured, dead, or orphaned animals can be reported to 1300 ANIMAL (1300 264 625). #Reefhealth