On Western Australia’s Ningaloo Reef, the shift from stark white to sickly brown paints a dire picture.<\/p>\n
“It’s a really dramatic change from all the colour and the vibrancy that a healthy coral shows,” marine scientist Zoe Richards said.<\/p>\n
“We’ve shifted to this dull phase where it’s algae dominating the corals.”<\/p>\n
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Of the 1,600 corals counted earlier in the year, only 600 are still alive. (Supplied: Minderoo Foundation)<\/p>\n
The most recent survey by researchers from Curtin University shows that more than 60 per cent of corals at eight sites in the reef’s northern lagoon have died.<\/p>\n
Of the 1,600 corals counted in March<\/a>, only 600 were still alive come late October.<\/p>\n The researchers returned to eight sites spanning 40 kilometres, identified during the marine heatwave. (Supplied: Minderoo Foundation)<\/p>\n The survey area stretched 40 kilometres from the Osprey and Tantabiddi sanctuary zones, an area that includes Turquoise Bay and several of the reef’s most popular tourist spots.<\/p>\n The findings mark a new phase for the World Heritage site, which was gripped by its worst-ever bleaching event<\/a> earlier this year.<\/p>\n Scientists warn ocean temperatures off WA are already warmer than average, with the summer months set to be “incredibly critical” for the remaining corals to hang on.<\/p>\n Coral bleaching vs mortality<\/p>\n When the ocean get too hot, corals expel the zooxanthellae algae that lives in their tissue.<\/p>\n ‘Hope spot’ to ‘skeletons’: Ningaloo’s ‘catastrophic’ event<\/a><\/p>\n In Western Australia, the damage to coral reefs including the World Heritage-listed Ningaloo has eclipsed any previous bleaching events.\u00a0<\/p>\n These microorganisms give corals their bright pastel colours and disease resistance.<\/p>\n Their absence creates the bleaching effect many Australians have become all too familiar with.<\/p>\n Unlike its east coast cousin, the Great Barrier Reef, the 270-kilometre Ningaloo Reef largely escaped the impact of climate change-induced ocean warming.<\/p>\n Coral taxonomist Zoe Richards says the change has \u00a0been “dramatic”. (Supplied: Minderoo Foundation)<\/p>\n But a record heatwave since December 2024<\/a> has flipped that fact in the extreme.<\/p>\n “The corals that were bleached earlier in the year have unfortunately succumbed to the heatwave and they have died,” Dr Richards said.<\/p>\n “Now, they are literally turned to rock with algae growing on top of them, it’s very sad.”Left ‘speechless’<\/p>\n PhD candidate David Juszkiewicz said it was not until researchers explored the reef at depth that they realised the extent of the decay.<\/p>\n “It’s when you scuba-dive and go down, you realise that there’s a lot of death underneath,” he said.<\/p>\n PhD student David Juszkiewicz says he is “really concerned” about the summer to come. (Supplied: Minderoo Foundation)<\/p>\n Mr Juszkiewicz compared the scene to walking through a forest after a bush fire.<\/p>\n “All the understorey vegetation, everything is burnt-out and charred,” he said.<\/p>\n “We’re speechless. There [are] no words that can explain what we saw.”<\/p>\n Some species were thought to be totally extinct from the sites surveyed. (Supplied: David Juszkiewicz)<\/p>\n Dr Richards said the ripple effect of the coral death was yet to be understood.<\/p>\n The eight lagoon sample sites with a large number of coral deaths were located between Tantabiddi and Osprey. (Google Earth: Data SIO, NOAA, US NAVY, NGA, GEBCO, Image Landsat, Copernicus)<\/p>\n “We’ve lost a lot of the diversity on the reef, the complexity,” she said.<\/p>\n “The coral is providing habitat for fish, for crustaceans, for shells, for worms \u2026 it’s quite likely they have all died.”<\/p>\n Dr Richards said the death of the corals was “just the beginning”.<\/p>\n “This summer and all the summers to come over the next decade are incredibly critical for these reefs to recover,” she said.<\/p>\n There was some hope, however, with corals in the nearby Exmouth Gulf<\/a> showing signs of resilience.<\/p>\n Towards the reef’s southern tip, deep corals at Coral Bay appeared to escape the brunt of the marine heat.<\/p>\n Much of the bay’s inner section was damaged by an anoxic event<\/a> in 2022.\u00a0<\/p>\n Crucial window ahead<\/p>\n The creep of rising water temperatures was first detected off WA’s coast about a year ago.<\/p>\n Principal research scientist at the Department of Biodiversity, Conservation and Attractions, Tom Holmes, said the summer months were expected to be less severe.<\/p>\n DBCA’s Exmouth Gulf marine coordinator Sallyann Gudge surveying sites of coral mortality this week. (Supplied: DBCA)<\/p>\n The department’s marine science team is in Exmouth, conducting surveys of its own.<\/p>\n “At the same time, in November of 2024, we were already seeing significant build-up of heat stress in the Kimberley, north-west atolls, and even down into the northern Pilbara,” Mr Holmes said.<\/p>\n “We’re looking probably slightly above average coming into [this] summer, but in the range of 0.4 to 0.8 degrees.<\/p>\n “It probably wouldn’t move into the bleaching threshold categories \u2026 [although] these are still predictions at this point in time and things can change.”<\/p>\n A record heatwave last summer bleached many of the reef’s famous corals. Few have survived. (Supplied: Brooke Pyke)<\/p>\n Pockets of hot water holding on from last year’s event remained a concern, particularly in the state’s south.<\/p>\n “A lot of residual heat was actually retained down in the south-west of WA and that really hasn’t cooled coming into this new summer,” Mr Holmes said.<\/p>\n “So, we’re already looking down at the south-west and seeing some significant heating already starting to occur there.”<\/p>\n Rallying for action<\/p>\n Exmouth glass-bottom boat tour operator Craig Kitson said the rotting corals had left him feeling “absolutely helpless”.<\/p>\n “The best way I can describe it is if you went out in your backyard and you saw your backyard dying and you didn’t know why and there’s no fix for it,” he said.<\/p>\n Exmouth tour operator Craig Kitson met with Environment Minister Murray Watt in Canberra last week. (Supplied: Australian Conservation Foundation)<\/p>\n Last week, Mr Kitson joined a delegation of regional Australians invited to Canberra by the Australian Conservation Foundation to lobby for stronger environmental protection<\/a> reforms.<\/p>\n<\/p>\n
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