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The first thing you notice as you enter the sparkling waters of a healthy coral reef is the sheer cacophony of the thing.
Healthy reefs crackle and pop with marine life. The chattering of fish and snapping of shrimp and other crustaceans sound to the naked ear like the “tick-tick-tick” of popping candy.
But vast tracts of Australia’s reefs have fallen silent, on the east and west coasts of Australia, their coral structures a ghostly dull white or smothered by sludge-coloured algae.
Ningaloo Reef, off Western Australia’s north-west coast, has largely escaped the increasingly frequent coral bleaching that has blighted the Great Barrier Reef.
The crystalline waters of Ningaloo Reef, pictured in healthier times.Credit: Anouska Freedman for ACF
This year, wide-scale bleaching of Ningaloo’s corals, across more than 100 kilometres, shows that no longer holds true.
During winter, this World Heritage-listed region plays host to migrating humpback whales and whale sharks, while dugongs, sharks, dolphins, manta rays and more than 500 species of fish call it home year-round.
Its tropical and temperate waters are considered by UNESCO to hold “outstanding universal value”. And it is here that some parts of the reef suffered up to 90 per cent bleaching, killing up to 50 per cent of corals, after a record-breaking marine heatwave.
“We had days, coming out in the first couple of weeks, where we were just sitting on the boat crying,” marine biologist Caitlin Fox says, aboard a glass-bottom boat at Ningaloo.
Marine biologist Caitlin Fox said she and others had wept when they saw the extent of bleaching.Credit: Bianca Hall
“It was just gut-wrenching. We just couldn’t really believe what we were looking at. It was extremely emotional.”
CSIRO marine ecologist Dr Damian Thomson, who leads the Ningaloo Outlook project, said scientists conducting annual surveys of the northern section of the reef in May found up to 90 per cent of coral had been bleached down to 20 metres’ depth, and the lowest cover of live coral since the agency began monitoring the region in 2007.
He estimated up to 50 per cent of the examined coral was dead in May, but said more would be dead now.
A green turtle swimming above turf algae-covered coral in the World Heritage-listed Ningaloo Reef.Credit: Anouska Freedman for ACF
“Seeing the bleaching that severe, to that depth, is so stark,” he said. “You realise your children are probably never going to see Ningaloo the way you saw it.”
“If corals are bleached only for a short period of time, they can recover, but that is very rare these days, because of the extensive and intense nature of most of the bleaching events.”
“When the water is hot for too long, and when the corals bleach heavily, as we’ve seen at Ningaloo, they rarely recover. So we would expect the total mortality from the heating event this summer to be more severe than the 50 per cent we observed in May; we expect there would be more coral that would have died since May.”
Last year, a marine heatwave enveloped Australia and stretched for 40 million square kilometres across the south-west Pacific, bringing intense heat, extreme rainfall and sea-level rises across our region.
On average, the average temperature was almost half a degree warmer than the 1991-2020 average across the region. In some parts of the Indian Ocean, sea surface temperatures of four degrees above average were recorded.
The World Meteorological Organisation confirmed 2024 was the hottest year on record in the south-west Pacific, while sea surface temperatures were the highest on record and ocean heat content was at near-record levels in 2024.
As corals suffer prolonged hot water temperatures, they expel the symbiotic algae living within their tissues as a stress response, a process that can turn coral white or – in some cases – bright fluorescent colours.
If water temperatures don’t fall, and corals don’t again take in symbiotic algae called zooxanthellae, they will die and become covered in sludgey “turf algae”.
Vast stretches of Ningaloo’s coral reefs visited by this masthead show the distinctive signs of turf algae.
Australian author Tim Winton, who has surfed and visited Ningaloo for decades, visited the remote Scott Reef in November, about 270 kilometres off the Kimberley coast, before the heatwave reached WA’s coastline.
“It was somewhere between 34 and 35 degrees in the water,” he says, shaking his head at the memory.
Author Tim Winton at Ningaloo in 2022.Credit: Violeta J Brosig, Blue Media Exmouth
“It’s not just unprecedented, which it clearly is, but it’s catastrophic. It’s just deeply distressing to see it unfolding … from the moment we got to Scott Reef, from the moment I got in the water, I was just totally overwhelmed by the water temperature, and I just knew that we were in so much trouble.”
Australian Conservation Foundation chief executive Kelly O’Shanassy, who toured Ningaloo with members of her team last week, described Ningaloo’s bleaching as “climate damage” resulting from governments failing to take action on climate change.
“It’s a result of burning coal and gas warming the planet,” she says. “The ocean is absorbing most of that warmth, and we are seeing the destruction of important places ecologically, and places that we love.”
“We’re seeing climate damage. We’re seeing the failure of governments to take action. In fact, we’re seeing governments approving – near these very waters – gas facilities that will operate for another 40 to 50 years.”
Australian Conservation Foundation chief executive Kelly O’Shanassy at Ningaloo Reef. Credit: Ari Balle-Bowness for ACF
ACF is calling on the federal government to include the impacts of climate change in national nature laws, arguing it is absurd to fail to consider climate harm in approving projects such as Woodside’s north-west shelf expansion.
“We call it climate consideration,” O’Shanassy says on board a boat gliding over Ningaloo Reef.
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“Some call it a climate trigger, but it’s about looking at the full emissions of a project and then assessing what type of damage those emissions might have on Australian ecosystems, and then [the minister] making a decision about whether that damage is acceptable or not.”
Environment Minister Murray Watt said it was clear climate change was affecting reefs worldwide, including the Ningaloo Reef.
“It underlines the need for Australia and the world to take urgent action, including reaching net zero emissions,” he said.
“That’s what the Albanese government is doing by setting ambitious 2030 emissions targets and driving up investment in renewables.
″Following the consideration of rigorous scientific and other advice, a proposed decision to approve the North West Shelf development has been made, subject to strict conditions, particularly relating to the impact of air emissions levels.
“In addition, this project is subject to the government’s strengthened mechanism, which requires it to reduce its emissions by around 5 per cent per year, and to be net zero by 2050.”
Australian Marine Conservation Society chief executive Paul Gamblin described the marine heatwave along the west coast of Australia, which settled on its reefs for months, as an “underwater bushfire”.
“It’s a reckoning, isn’t it?” Gamblin said.
“For anyone who thought that Australia’s marine environment might not be affected by climate change, this is the year that will be recorded when Australia did face that reckoning … there’s nowhere, really, that we can hope to escape those impacts at this stage.”
Craig Kitson, Owner of Ningaloo Glass Bottom Boats, has lived and dived in Ningaloo for 25 years, says this means tourists think they’re looking at healthy corals when instead they’re watching a phenomenon known as a “beautiful death” or “spectacular death”.
Tour operator Craig Kitson says it’s difficult for tourists to grasp the scale of the damage.Credit: Bianca Hall
As they bleach, some corals take on beautiful and fluorescent colours as they bleach before they expel the algae living within their structures.
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“What we find on tour is that a lot of people don’t actually know what they’re looking at,” Kitson says.
“It’s a really hard thing to explain to people because there’s still coral structure there [despite the bleaching] … people were blown away by the colours through the glass because coral does this last show before it dies a beautiful death. And they were all saying, ‘wow, that’s the most amazing coral I’ve ever seen’.
“But it’s screaming out.”
The author travelled to Exmouth and Ningaloo Reef courtesy of the Australian Conservation Foundation.
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