Ningaloo—Coral bleaching
29. Hon Dr Brad Pettitt to the Minister for the Environment:
In February, world heritage listed Ningaloo Marine Park suffered severe coral bleaching after sea temperatures rose to two to three degrees Celsius above the long-term average in the Gascoyne.
In March, the Department of Biodiversity, Conservation and Attractions (DBCA) confirmed they have been carrying out marine heatwave monitoring.
(1) What percentage of Ningaloo coral has been identified by DBCA as—
(a) having been bleached; and
(b) dead?
(2) What modelling has DBCA conducted in the past two years in relation to coral bleaching at Ningaloo?
(3) What does DBCA's long-term modelling of coral bleaching at Ningaloo predict if global temperatures rise above 1.5 degrees?
(4) How much greater does DBCA anticipate sea temperatures at Ningaloo to rise compared to global averages?
Hon Samantha Rowe replied:
I thank the honourable member for some notice of the question. I answer on behalf of the minister.
(1) (a) While bleaching severity is patchy, observations indicate that the most severe impacts are currently within the lagoon, to the north of Point Cloates and within the Exmouth Gulf. While minimal bleaching was observed at some locations, others had up to 60% to 80% of corals bleached or showing signs of heat stress.
(b) Corals can persist in a bleached but live state for many months and have the ability to recover if appropriate conditions occur. The coral mortality caused by the current event will not be known until the second half of 2025 at the earliest.
(2)–(3) DBCA has not conducted independent modelling of bleaching risk at Ningaloo. Modelling undertaken by other agencies indicates that by 2041, Ningaloo is predicted to experience significant bleaching twice every decade and annually by 2049, under current conditions.
(4) Information on regional seawater temperature predictions is not available at a detailed enough scale to predict how much sea temperatures might rise in relation to global averages.
