‘Entire reef' under threat by pest on Cook Islands
These makeshift tools are their best weapons in the war against crown-of-thorns starfish, a coral-munching species eating through tropical reefs already weakened by climate change.
The Cook Islands, a South Pacific nation of about 17,000 people, is in the grips of a years-long outbreak, says marine biologist Teina Rongo.
'It can completely kill off the entire reef, right around the island,' said Rongo, who organises volunteers protecting the reefs fringing the isle of Rarotonga.
'I think there seems to be a Pacific-wide outbreak at the moment, because we're hearing other countries are facing similar challenges.'
A single crown-of-thorns adult can eat more than 10 square metres (110 square feet) of reef each year, squeezing its stomach through its mouth to coat coral in digestive juices.
They pose a major threat to Australia's Great Barrier Reef, where scientists have developed robots that hunt down the prickly invertebrates and inject them with poison.
'At the moment, you basically kill them by injection,' said researcher Sven Uthicke, from the Australian Institute of Marine Science.
'It could be vinegar, it could be lime juice or ox bile.
'Others are building chemical attraction traps. It's all very promising – but it's in the development stage.'
Rongo finds it quickest to pry the feasting starfish loose using a wooden stick cut from the dense timber of the Pacific Ironwood tree.
'Basically, we use a stick with a hook at the end,' he said.
'We've made some modifications over time because we were getting pricked by these starfish. 'It's painful.'
Named for their hundreds of venomous spikes, crown-of-thorns starfish have as many as 21 fleshy arms and can grow larger than a car tyre.
They are typically found in such low numbers that they are not considered a problem, but sporadically populations explode in a feeding frenzy that rapidly strips the life from reefs.
They spawn in 'plague proportions', according to the Australian Institute of Marine Science, and are a major driver of coral loss.
From the Red Sea to the Pacific Ocean, crown-of-thorns outbreaks appear to be becoming both more frequent and more severe.
'Some argue that the crown-of-thorns has become chronic in the last few decades,' said Rongo, talking about the reefs of the South Pacific.
Scientists suspect these outbreaks are triggered by a mix of factors, including nutrients leached into the sea from agriculture and fluctuations in natural predators.
But the damage they can cause is getting worse as reefs are weakened by climate change-fuelled coral bleaching and ocean acidification.
'This is why it's important for us to help the reef,' says Rongo.
Scuba divers scour the Cook Islands' reefs for hard-to-spot starfish wedged into dimly lit crevices.
Once peeled off the coral, the starfish are pierced with a thick rope so they can be dragged back up to a waiting boat.
The day's haul is dumped into a plastic chest before the starfish are lugged ashore to be counted, measured and mulched for garden fertiliser.
They are known as 'taramea' in Cook Islands Maori, which loosely translates to 'spiky thing'.
The volunteer divers working with Rongo and his environmental group Korero O Te Orau – or Knowledge of the Land, Sky and Sea – remove thousands of starfish every year.
Rongo is spurred by the devastation from the nation's last major infestation in the 1990s.
'I was part of that eradication effort.
'We were too late when we did decide to do something about it. It went on and ended up killing the reef.'
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Australia's other great coral reef is choking. And nobody's watching
Nicole Ryan could see the damage from the boat. Floating above the usually vibrant waters of Rowley Shoals, 300 kilometres west of Broome, the coral beneath was unnaturally pale - a visible warning before she even entered the water. Once she dived in, the scale of the destruction became heartbreakingly clear. Much had already died. The coral that still had colour was likely living on borrowed time. "I'm just laughing because I'm trying not to cry," said Ms Ryan, an ecologist with the Australian Institute of Marine Science (AIMS), who coordinates a group of researchers and agencies monitoring bleaching of Western Australia's reefs. "It's an awful thing to see because that place is just beautiful - it's this beacon of pristine coral reef." The prolonged marine heatwave behind the devastation lasted, off and on, for nine months - triggering a mass bleaching event across the state. From the rarely visited Rowley Shoals to the World Heritage-listed Ningaloo reef, almost no area has been spared. "It's actually warmer than what is normal for the warmest time of the year," Ms Ryan said. "I think this is quite the largest footprint of heat stress and bleaching that we've ever seen." She described it as the worst coral die-off she'd seen. "A lot of the structure was still there, so it's pretty eerie. It's just there's no life to it." The same marine heatwave that struck WA in 2024 affected nearly 40 million square kilometres of ocean globally. It began off the state's coast in August and persisted until May the following year. The intensity wasn't just unusual - it was historic. It triggered a mass coral bleaching event that has devastated one of the world's most pristine fringing reefs and affected all of WA's unique coral colonies. "What's been more telling is just the accumulation and the resulting heat stress that we've seen," Ms Ryan said. "It's actually warmer than what is normal for the warmest time of the year." Many of WA's coral systems - including those that had previously escaped bleaching - are now struggling thanks to unprecedented thermal stress. "For many of these reefs, which is actually quite a frightening thing to witness, it's the worst of it we've seen for reefs that have typically escaped bleaching in the past," she said. Along Ningaloo reef, where normal water temperatures can nudge 30 degrees in hotter months, almost no area was left untouched. Aerial surveys conducted through much of 2025 revealed bleaching across its full 260-kilometre span - from the southern sections near Coral Bay to the northern reaches around Exmouth. "I think this is quite the largest footprint of heat stress and bleaching that we've ever seen," Ms Ryan said. Coral bleaching is a sadly familiar phenomenon to most Australians but has, until now, been associated with the Great Barrier Reef off Queensland's coast. The world's largest living structure experienced its fifth mass bleaching event in eight years during the 2023-24 summer and, in late July, narrowly missed being placed on the global list of in-danger World Heritage sites. Even tourists aboard glass-bottom boat tours have been able to spot the pale, ghostlike patches below - a visual marker of coral under stress. Coral appears "bleached" under stress because it expels the algae that give it colour - and a food source - leaving it white. When ocean temperatures rise, what's left behind is the white skeleton - vulnerable and starving. Mass coral bleaching is a recent phenomenon thanks to climate change. No records of large-scale bleaching exist before the 1980s and scientists say the ocean temperature is rising thanks to a heating climate. While corals exist happily in relatively warm seas, any rises between 1 and 2 degrees Celsius above the normal summer maximum for more than a few weeks at a time can cause heat stress. Longtime Coral Bay marine guide and snorkelling operator Frazer McGregor knew something was wrong when videos of manta rays appeared on social media - filmed not in Ningaloo's usual turquoise waters, but more than 1000 kilometres south off Perth. With a span of up to five metres "wing" tip to tip, these gentle gymnasts of the ocean are at home in the tropics and sub-tropics but had likely been pushed into cooler waters by rising sea temperatures. "They are super inquisitive and you can see them looking at you," he said as he skippered his winter tourist-laden boat through shallow turquoise waters in search of whales, dolphins, turtles and sharks. "You can almost get a feeling that their brains work over time to work out what we are." But climate change and heat are not the only threats to Ningaloo, which attracts hundreds of thousands of tourists each year to fish, swim with whale sharks, and dive and snorkel in startlingly clear waters alongside 200 species of coral and 500 different types of fish. Mr McGregor says, lately, it's become harder to find the large marine animals - and to have meaningful encounters with them. Boating traffic, people - and their desire to get the perfect Instagram picture - were all taking a toll. "It is more difficult to get and have good interactions with big animals and that's because they're staying away because of more people, more boats," he said. "Don't get me wrong: I am part of that problem as well as everybody else because I'm taking however many people out every day." But successful conservation efforts to help bring humpback whales from the brink of extinction showed regulation could have a big impact, he said. "If we do ease up the pressure, we can help things recover," Mr McGregor said. Right now, some key fish populations are in decline. "That's a combination of recreational fishing and climate change," he said. "It stands to reason that more fishing pressure's gonna take more fish out, and we've seen decreases in certain species of fish." But in the 25 years since Mr McGregor stopped at remote Coral Bay on a trip around Australia and decided to stay, much of the unique wonder of the reef remains relatively unscathed. "It's such a resilient and healthy reef that you may not notice those changes yet, and it may be that they become a catastrophic change when and if they happen," he said. "But, in general, I'm still taking people to places and showing them things that are the same as they were when I got here." Tourists willing and able to cross WA's vast deserts or the Indian Ocean to reach Ningaloo can still marvel as dugongs graze the sea grass, rising for breath every five minutes or so above the surface. They can see humpback whale spouts dotting the horizon and dolphins playing, swim with manta rays, and glide over loggerhead turtles taking lazy paddles across the sea floor. But those invested in the reef's future agree monitoring change is not enough. As politicians squabble over the net zero emissions policy far away in Canberra, finding solutions is one of the main priorities for philanthropic bodies like the Minderoo Foundation, WA mining billionaire Andrew "Twiggy" Forrest's charity. Minderoo opened a state-of-the-art lab in Exmouth at the gateway to Ningaloo in 2021 to support research on the reef given its remote location. The lab has had recent, initial success in breeding heat-resistant coral at Ningaloo on the back of similar work on the Great Barrier Reef. "What we were able to do is ... apply the lessons that we had developed on the Great Barrier Reef, bring them over to Ningaloo with a few tweaks, and we were able to increase the heat tolerance of baby corals by over two times," lab research lead Kate Quigley said. Corals were key to the reef's health because they were ecosystem builders. "Without corals, we don't get many other different organisms that we are interested in saving and preserving and using," Dr Quigley said. "If we can figure out how to make corals more resilient to future temperatures, that will help the rest of the ecosystem." But locally-focused solutions needed to be coupled with action on climate change. "As exciting as this work is, especially around the breeding of heat-tolerant corals, it must come in conjunction with strong emissions control," she said. "We need to start bringing down emissions for these kind of conservation actions to work in the long term. "This is not a get-out-of-jail-free card." Nicole Ryan could see the damage from the boat. Floating above the usually vibrant waters of Rowley Shoals, 300 kilometres west of Broome, the coral beneath was unnaturally pale - a visible warning before she even entered the water. Once she dived in, the scale of the destruction became heartbreakingly clear. Much had already died. The coral that still had colour was likely living on borrowed time. "I'm just laughing because I'm trying not to cry," said Ms Ryan, an ecologist with the Australian Institute of Marine Science (AIMS), who coordinates a group of researchers and agencies monitoring bleaching of Western Australia's reefs. "It's an awful thing to see because that place is just beautiful - it's this beacon of pristine coral reef." The prolonged marine heatwave behind the devastation lasted, off and on, for nine months - triggering a mass bleaching event across the state. From the rarely visited Rowley Shoals to the World Heritage-listed Ningaloo reef, almost no area has been spared. "It's actually warmer than what is normal for the warmest time of the year," Ms Ryan said. "I think this is quite the largest footprint of heat stress and bleaching that we've ever seen." She described it as the worst coral die-off she'd seen. "A lot of the structure was still there, so it's pretty eerie. It's just there's no life to it." The same marine heatwave that struck WA in 2024 affected nearly 40 million square kilometres of ocean globally. It began off the state's coast in August and persisted until May the following year. The intensity wasn't just unusual - it was historic. It triggered a mass coral bleaching event that has devastated one of the world's most pristine fringing reefs and affected all of WA's unique coral colonies. "What's been more telling is just the accumulation and the resulting heat stress that we've seen," Ms Ryan said. "It's actually warmer than what is normal for the warmest time of the year." Many of WA's coral systems - including those that had previously escaped bleaching - are now struggling thanks to unprecedented thermal stress. "For many of these reefs, which is actually quite a frightening thing to witness, it's the worst of it we've seen for reefs that have typically escaped bleaching in the past," she said. Along Ningaloo reef, where normal water temperatures can nudge 30 degrees in hotter months, almost no area was left untouched. Aerial surveys conducted through much of 2025 revealed bleaching across its full 260-kilometre span - from the southern sections near Coral Bay to the northern reaches around Exmouth. "I think this is quite the largest footprint of heat stress and bleaching that we've ever seen," Ms Ryan said. Coral bleaching is a sadly familiar phenomenon to most Australians but has, until now, been associated with the Great Barrier Reef off Queensland's coast. The world's largest living structure experienced its fifth mass bleaching event in eight years during the 2023-24 summer and, in late July, narrowly missed being placed on the global list of in-danger World Heritage sites. Even tourists aboard glass-bottom boat tours have been able to spot the pale, ghostlike patches below - a visual marker of coral under stress. Coral appears "bleached" under stress because it expels the algae that give it colour - and a food source - leaving it white. When ocean temperatures rise, what's left behind is the white skeleton - vulnerable and starving. Mass coral bleaching is a recent phenomenon thanks to climate change. No records of large-scale bleaching exist before the 1980s and scientists say the ocean temperature is rising thanks to a heating climate. While corals exist happily in relatively warm seas, any rises between 1 and 2 degrees Celsius above the normal summer maximum for more than a few weeks at a time can cause heat stress. Longtime Coral Bay marine guide and snorkelling operator Frazer McGregor knew something was wrong when videos of manta rays appeared on social media - filmed not in Ningaloo's usual turquoise waters, but more than 1000 kilometres south off Perth. With a span of up to five metres "wing" tip to tip, these gentle gymnasts of the ocean are at home in the tropics and sub-tropics but had likely been pushed into cooler waters by rising sea temperatures. "They are super inquisitive and you can see them looking at you," he said as he skippered his winter tourist-laden boat through shallow turquoise waters in search of whales, dolphins, turtles and sharks. "You can almost get a feeling that their brains work over time to work out what we are." But climate change and heat are not the only threats to Ningaloo, which attracts hundreds of thousands of tourists each year to fish, swim with whale sharks, and dive and snorkel in startlingly clear waters alongside 200 species of coral and 500 different types of fish. Mr McGregor says, lately, it's become harder to find the large marine animals - and to have meaningful encounters with them. Boating traffic, people - and their desire to get the perfect Instagram picture - were all taking a toll. "It is more difficult to get and have good interactions with big animals and that's because they're staying away because of more people, more boats," he said. "Don't get me wrong: I am part of that problem as well as everybody else because I'm taking however many people out every day." But successful conservation efforts to help bring humpback whales from the brink of extinction showed regulation could have a big impact, he said. "If we do ease up the pressure, we can help things recover," Mr McGregor said. Right now, some key fish populations are in decline. "That's a combination of recreational fishing and climate change," he said. "It stands to reason that more fishing pressure's gonna take more fish out, and we've seen decreases in certain species of fish." But in the 25 years since Mr McGregor stopped at remote Coral Bay on a trip around Australia and decided to stay, much of the unique wonder of the reef remains relatively unscathed. "It's such a resilient and healthy reef that you may not notice those changes yet, and it may be that they become a catastrophic change when and if they happen," he said. "But, in general, I'm still taking people to places and showing them things that are the same as they were when I got here." Tourists willing and able to cross WA's vast deserts or the Indian Ocean to reach Ningaloo can still marvel as dugongs graze the sea grass, rising for breath every five minutes or so above the surface. They can see humpback whale spouts dotting the horizon and dolphins playing, swim with manta rays, and glide over loggerhead turtles taking lazy paddles across the sea floor. But those invested in the reef's future agree monitoring change is not enough. As politicians squabble over the net zero emissions policy far away in Canberra, finding solutions is one of the main priorities for philanthropic bodies like the Minderoo Foundation, WA mining billionaire Andrew "Twiggy" Forrest's charity. Minderoo opened a state-of-the-art lab in Exmouth at the gateway to Ningaloo in 2021 to support research on the reef given its remote location. The lab has had recent, initial success in breeding heat-resistant coral at Ningaloo on the back of similar work on the Great Barrier Reef. "What we were able to do is ... apply the lessons that we had developed on the Great Barrier Reef, bring them over to Ningaloo with a few tweaks, and we were able to increase the heat tolerance of baby corals by over two times," lab research lead Kate Quigley said. Corals were key to the reef's health because they were ecosystem builders. "Without corals, we don't get many other different organisms that we are interested in saving and preserving and using," Dr Quigley said. "If we can figure out how to make corals more resilient to future temperatures, that will help the rest of the ecosystem." But locally-focused solutions needed to be coupled with action on climate change. "As exciting as this work is, especially around the breeding of heat-tolerant corals, it must come in conjunction with strong emissions control," she said. "We need to start bringing down emissions for these kind of conservation actions to work in the long term. "This is not a get-out-of-jail-free card." Nicole Ryan could see the damage from the boat. Floating above the usually vibrant waters of Rowley Shoals, 300 kilometres west of Broome, the coral beneath was unnaturally pale - a visible warning before she even entered the water. Once she dived in, the scale of the destruction became heartbreakingly clear. Much had already died. The coral that still had colour was likely living on borrowed time. "I'm just laughing because I'm trying not to cry," said Ms Ryan, an ecologist with the Australian Institute of Marine Science (AIMS), who coordinates a group of researchers and agencies monitoring bleaching of Western Australia's reefs. "It's an awful thing to see because that place is just beautiful - it's this beacon of pristine coral reef." The prolonged marine heatwave behind the devastation lasted, off and on, for nine months - triggering a mass bleaching event across the state. From the rarely visited Rowley Shoals to the World Heritage-listed Ningaloo reef, almost no area has been spared. "It's actually warmer than what is normal for the warmest time of the year," Ms Ryan said. "I think this is quite the largest footprint of heat stress and bleaching that we've ever seen." She described it as the worst coral die-off she'd seen. "A lot of the structure was still there, so it's pretty eerie. It's just there's no life to it." The same marine heatwave that struck WA in 2024 affected nearly 40 million square kilometres of ocean globally. It began off the state's coast in August and persisted until May the following year. The intensity wasn't just unusual - it was historic. It triggered a mass coral bleaching event that has devastated one of the world's most pristine fringing reefs and affected all of WA's unique coral colonies. "What's been more telling is just the accumulation and the resulting heat stress that we've seen," Ms Ryan said. "It's actually warmer than what is normal for the warmest time of the year." Many of WA's coral systems - including those that had previously escaped bleaching - are now struggling thanks to unprecedented thermal stress. "For many of these reefs, which is actually quite a frightening thing to witness, it's the worst of it we've seen for reefs that have typically escaped bleaching in the past," she said. Along Ningaloo reef, where normal water temperatures can nudge 30 degrees in hotter months, almost no area was left untouched. Aerial surveys conducted through much of 2025 revealed bleaching across its full 260-kilometre span - from the southern sections near Coral Bay to the northern reaches around Exmouth. "I think this is quite the largest footprint of heat stress and bleaching that we've ever seen," Ms Ryan said. Coral bleaching is a sadly familiar phenomenon to most Australians but has, until now, been associated with the Great Barrier Reef off Queensland's coast. The world's largest living structure experienced its fifth mass bleaching event in eight years during the 2023-24 summer and, in late July, narrowly missed being placed on the global list of in-danger World Heritage sites. Even tourists aboard glass-bottom boat tours have been able to spot the pale, ghostlike patches below - a visual marker of coral under stress. Coral appears "bleached" under stress because it expels the algae that give it colour - and a food source - leaving it white. When ocean temperatures rise, what's left behind is the white skeleton - vulnerable and starving. Mass coral bleaching is a recent phenomenon thanks to climate change. No records of large-scale bleaching exist before the 1980s and scientists say the ocean temperature is rising thanks to a heating climate. While corals exist happily in relatively warm seas, any rises between 1 and 2 degrees Celsius above the normal summer maximum for more than a few weeks at a time can cause heat stress. Longtime Coral Bay marine guide and snorkelling operator Frazer McGregor knew something was wrong when videos of manta rays appeared on social media - filmed not in Ningaloo's usual turquoise waters, but more than 1000 kilometres south off Perth. With a span of up to five metres "wing" tip to tip, these gentle gymnasts of the ocean are at home in the tropics and sub-tropics but had likely been pushed into cooler waters by rising sea temperatures. "They are super inquisitive and you can see them looking at you," he said as he skippered his winter tourist-laden boat through shallow turquoise waters in search of whales, dolphins, turtles and sharks. "You can almost get a feeling that their brains work over time to work out what we are." But climate change and heat are not the only threats to Ningaloo, which attracts hundreds of thousands of tourists each year to fish, swim with whale sharks, and dive and snorkel in startlingly clear waters alongside 200 species of coral and 500 different types of fish. Mr McGregor says, lately, it's become harder to find the large marine animals - and to have meaningful encounters with them. Boating traffic, people - and their desire to get the perfect Instagram picture - were all taking a toll. "It is more difficult to get and have good interactions with big animals and that's because they're staying away because of more people, more boats," he said. "Don't get me wrong: I am part of that problem as well as everybody else because I'm taking however many people out every day." But successful conservation efforts to help bring humpback whales from the brink of extinction showed regulation could have a big impact, he said. "If we do ease up the pressure, we can help things recover," Mr McGregor said. Right now, some key fish populations are in decline. "That's a combination of recreational fishing and climate change," he said. "It stands to reason that more fishing pressure's gonna take more fish out, and we've seen decreases in certain species of fish." But in the 25 years since Mr McGregor stopped at remote Coral Bay on a trip around Australia and decided to stay, much of the unique wonder of the reef remains relatively unscathed. "It's such a resilient and healthy reef that you may not notice those changes yet, and it may be that they become a catastrophic change when and if they happen," he said. "But, in general, I'm still taking people to places and showing them things that are the same as they were when I got here." Tourists willing and able to cross WA's vast deserts or the Indian Ocean to reach Ningaloo can still marvel as dugongs graze the sea grass, rising for breath every five minutes or so above the surface. They can see humpback whale spouts dotting the horizon and dolphins playing, swim with manta rays, and glide over loggerhead turtles taking lazy paddles across the sea floor. But those invested in the reef's future agree monitoring change is not enough. As politicians squabble over the net zero emissions policy far away in Canberra, finding solutions is one of the main priorities for philanthropic bodies like the Minderoo Foundation, WA mining billionaire Andrew "Twiggy" Forrest's charity. Minderoo opened a state-of-the-art lab in Exmouth at the gateway to Ningaloo in 2021 to support research on the reef given its remote location. The lab has had recent, initial success in breeding heat-resistant coral at Ningaloo on the back of similar work on the Great Barrier Reef. "What we were able to do is ... apply the lessons that we had developed on the Great Barrier Reef, bring them over to Ningaloo with a few tweaks, and we were able to increase the heat tolerance of baby corals by over two times," lab research lead Kate Quigley said. Corals were key to the reef's health because they were ecosystem builders. "Without corals, we don't get many other different organisms that we are interested in saving and preserving and using," Dr Quigley said. "If we can figure out how to make corals more resilient to future temperatures, that will help the rest of the ecosystem." But locally-focused solutions needed to be coupled with action on climate change. "As exciting as this work is, especially around the breeding of heat-tolerant corals, it must come in conjunction with strong emissions control," she said. "We need to start bringing down emissions for these kind of conservation actions to work in the long term. "This is not a get-out-of-jail-free card." Nicole Ryan could see the damage from the boat. Floating above the usually vibrant waters of Rowley Shoals, 300 kilometres west of Broome, the coral beneath was unnaturally pale - a visible warning before she even entered the water. Once she dived in, the scale of the destruction became heartbreakingly clear. Much had already died. The coral that still had colour was likely living on borrowed time. "I'm just laughing because I'm trying not to cry," said Ms Ryan, an ecologist with the Australian Institute of Marine Science (AIMS), who coordinates a group of researchers and agencies monitoring bleaching of Western Australia's reefs. "It's an awful thing to see because that place is just beautiful - it's this beacon of pristine coral reef." The prolonged marine heatwave behind the devastation lasted, off and on, for nine months - triggering a mass bleaching event across the state. From the rarely visited Rowley Shoals to the World Heritage-listed Ningaloo reef, almost no area has been spared. "It's actually warmer than what is normal for the warmest time of the year," Ms Ryan said. "I think this is quite the largest footprint of heat stress and bleaching that we've ever seen." She described it as the worst coral die-off she'd seen. "A lot of the structure was still there, so it's pretty eerie. It's just there's no life to it." The same marine heatwave that struck WA in 2024 affected nearly 40 million square kilometres of ocean globally. It began off the state's coast in August and persisted until May the following year. The intensity wasn't just unusual - it was historic. It triggered a mass coral bleaching event that has devastated one of the world's most pristine fringing reefs and affected all of WA's unique coral colonies. "What's been more telling is just the accumulation and the resulting heat stress that we've seen," Ms Ryan said. "It's actually warmer than what is normal for the warmest time of the year." Many of WA's coral systems - including those that had previously escaped bleaching - are now struggling thanks to unprecedented thermal stress. "For many of these reefs, which is actually quite a frightening thing to witness, it's the worst of it we've seen for reefs that have typically escaped bleaching in the past," she said. Along Ningaloo reef, where normal water temperatures can nudge 30 degrees in hotter months, almost no area was left untouched. Aerial surveys conducted through much of 2025 revealed bleaching across its full 260-kilometre span - from the southern sections near Coral Bay to the northern reaches around Exmouth. "I think this is quite the largest footprint of heat stress and bleaching that we've ever seen," Ms Ryan said. Coral bleaching is a sadly familiar phenomenon to most Australians but has, until now, been associated with the Great Barrier Reef off Queensland's coast. The world's largest living structure experienced its fifth mass bleaching event in eight years during the 2023-24 summer and, in late July, narrowly missed being placed on the global list of in-danger World Heritage sites. Even tourists aboard glass-bottom boat tours have been able to spot the pale, ghostlike patches below - a visual marker of coral under stress. Coral appears "bleached" under stress because it expels the algae that give it colour - and a food source - leaving it white. When ocean temperatures rise, what's left behind is the white skeleton - vulnerable and starving. Mass coral bleaching is a recent phenomenon thanks to climate change. No records of large-scale bleaching exist before the 1980s and scientists say the ocean temperature is rising thanks to a heating climate. While corals exist happily in relatively warm seas, any rises between 1 and 2 degrees Celsius above the normal summer maximum for more than a few weeks at a time can cause heat stress. Longtime Coral Bay marine guide and snorkelling operator Frazer McGregor knew something was wrong when videos of manta rays appeared on social media - filmed not in Ningaloo's usual turquoise waters, but more than 1000 kilometres south off Perth. With a span of up to five metres "wing" tip to tip, these gentle gymnasts of the ocean are at home in the tropics and sub-tropics but had likely been pushed into cooler waters by rising sea temperatures. "They are super inquisitive and you can see them looking at you," he said as he skippered his winter tourist-laden boat through shallow turquoise waters in search of whales, dolphins, turtles and sharks. "You can almost get a feeling that their brains work over time to work out what we are." But climate change and heat are not the only threats to Ningaloo, which attracts hundreds of thousands of tourists each year to fish, swim with whale sharks, and dive and snorkel in startlingly clear waters alongside 200 species of coral and 500 different types of fish. Mr McGregor says, lately, it's become harder to find the large marine animals - and to have meaningful encounters with them. Boating traffic, people - and their desire to get the perfect Instagram picture - were all taking a toll. "It is more difficult to get and have good interactions with big animals and that's because they're staying away because of more people, more boats," he said. "Don't get me wrong: I am part of that problem as well as everybody else because I'm taking however many people out every day." But successful conservation efforts to help bring humpback whales from the brink of extinction showed regulation could have a big impact, he said. "If we do ease up the pressure, we can help things recover," Mr McGregor said. Right now, some key fish populations are in decline. "That's a combination of recreational fishing and climate change," he said. "It stands to reason that more fishing pressure's gonna take more fish out, and we've seen decreases in certain species of fish." But in the 25 years since Mr McGregor stopped at remote Coral Bay on a trip around Australia and decided to stay, much of the unique wonder of the reef remains relatively unscathed. "It's such a resilient and healthy reef that you may not notice those changes yet, and it may be that they become a catastrophic change when and if they happen," he said. "But, in general, I'm still taking people to places and showing them things that are the same as they were when I got here." Tourists willing and able to cross WA's vast deserts or the Indian Ocean to reach Ningaloo can still marvel as dugongs graze the sea grass, rising for breath every five minutes or so above the surface. They can see humpback whale spouts dotting the horizon and dolphins playing, swim with manta rays, and glide over loggerhead turtles taking lazy paddles across the sea floor. But those invested in the reef's future agree monitoring change is not enough. As politicians squabble over the net zero emissions policy far away in Canberra, finding solutions is one of the main priorities for philanthropic bodies like the Minderoo Foundation, WA mining billionaire Andrew "Twiggy" Forrest's charity. Minderoo opened a state-of-the-art lab in Exmouth at the gateway to Ningaloo in 2021 to support research on the reef given its remote location. The lab has had recent, initial success in breeding heat-resistant coral at Ningaloo on the back of similar work on the Great Barrier Reef. "What we were able to do is ... apply the lessons that we had developed on the Great Barrier Reef, bring them over to Ningaloo with a few tweaks, and we were able to increase the heat tolerance of baby corals by over two times," lab research lead Kate Quigley said. Corals were key to the reef's health because they were ecosystem builders. "Without corals, we don't get many other different organisms that we are interested in saving and preserving and using," Dr Quigley said. "If we can figure out how to make corals more resilient to future temperatures, that will help the rest of the ecosystem." But locally-focused solutions needed to be coupled with action on climate change. "As exciting as this work is, especially around the breeding of heat-tolerant corals, it must come in conjunction with strong emissions control," she said. "We need to start bringing down emissions for these kind of conservation actions to work in the long term. "This is not a get-out-of-jail-free card."
News.com.au
25-07-2025
- News.com.au
‘Entire reef' under threat by pest on Cook Islands
Divers clutch wooden spears as they plunge beneath the waves, hunting hordes of hungry starfish destroying the coral reefs around the Cook Islands. These makeshift tools are their best weapons in the war against crown-of-thorns starfish, a coral-munching species eating through tropical reefs already weakened by climate change. The Cook Islands, a South Pacific nation of about 17,000 people, is in the grips of a years-long outbreak, says marine biologist Teina Rongo. 'It can completely kill off the entire reef, right around the island,' said Rongo, who organises volunteers protecting the reefs fringing the isle of Rarotonga. 'I think there seems to be a Pacific-wide outbreak at the moment, because we're hearing other countries are facing similar challenges.' A single crown-of-thorns adult can eat more than 10 square metres (110 square feet) of reef each year, squeezing its stomach through its mouth to coat coral in digestive juices. They pose a major threat to Australia's Great Barrier Reef, where scientists have developed robots that hunt down the prickly invertebrates and inject them with poison. 'At the moment, you basically kill them by injection,' said researcher Sven Uthicke, from the Australian Institute of Marine Science. 'It could be vinegar, it could be lime juice or ox bile. 'Others are building chemical attraction traps. It's all very promising – but it's in the development stage.' Rongo finds it quickest to pry the feasting starfish loose using a wooden stick cut from the dense timber of the Pacific Ironwood tree. 'Basically, we use a stick with a hook at the end,' he said. 'We've made some modifications over time because we were getting pricked by these starfish. 'It's painful.' Named for their hundreds of venomous spikes, crown-of-thorns starfish have as many as 21 fleshy arms and can grow larger than a car tyre. They are typically found in such low numbers that they are not considered a problem, but sporadically populations explode in a feeding frenzy that rapidly strips the life from reefs. They spawn in 'plague proportions', according to the Australian Institute of Marine Science, and are a major driver of coral loss. From the Red Sea to the Pacific Ocean, crown-of-thorns outbreaks appear to be becoming both more frequent and more severe. 'Some argue that the crown-of-thorns has become chronic in the last few decades,' said Rongo, talking about the reefs of the South Pacific. Scientists suspect these outbreaks are triggered by a mix of factors, including nutrients leached into the sea from agriculture and fluctuations in natural predators. But the damage they can cause is getting worse as reefs are weakened by climate change-fuelled coral bleaching and ocean acidification. 'This is why it's important for us to help the reef,' says Rongo. Scuba divers scour the Cook Islands' reefs for hard-to-spot starfish wedged into dimly lit crevices. Once peeled off the coral, the starfish are pierced with a thick rope so they can be dragged back up to a waiting boat. The day's haul is dumped into a plastic chest before the starfish are lugged ashore to be counted, measured and mulched for garden fertiliser. They are known as 'taramea' in Cook Islands Maori, which loosely translates to 'spiky thing'. The volunteer divers working with Rongo and his environmental group Korero O Te Orau – or Knowledge of the Land, Sky and Sea – remove thousands of starfish every year. Rongo is spurred by the devastation from the nation's last major infestation in the 1990s. 'I was part of that eradication effort. 'We were too late when we did decide to do something about it. It went on and ended up killing the reef.'
News.com.au
24-07-2025
- News.com.au
Cook Islands wages war on 'plague' of hungry starfish
Divers clutch wooden spears as they plunge beneath the waves, hunting hordes of hungry starfish destroying the coral reefs around the Cook Islands. These makeshift tools are their best weapons in the war against crown-of-thorns starfish, a coral-munching species eating through tropical reefs already weakened by climate change. The Cook Islands, a South Pacific nation of about 17,000 people, is in the grips of a years-long outbreak, says marine biologist Teina Rongo. "It can completely kill off the entire reef, right around the island," said Rongo, who organises volunteers protecting the reefs fringing the isle of Rarotonga. "I think there seems to be a Pacific-wide outbreak at the moment, because we're hearing other countries are facing similar challenges." A single crown-of-thorns adult can eat more than 10 square metres (110 square feet) of reef each year, squeezing its stomach through its mouth to coat coral in digestive juices. They pose a major threat to Australia's Great Barrier Reef, where scientists have developed robots that hunt down the prickly invertebrates and inject them with poison. "At the moment, you basically kill them by injection," said researcher Sven Uthicke, from the Australian Institute of Marine Science. "It could be vinegar, it could be lime juice or ox bile. "Others are building chemical attraction traps. It's all very promising -- but it's in the development stage." Rongo finds it quickest to pry the feasting starfish loose using a wooden stick cut from the dense timber of the Pacific Ironwood tree. "Basically, we use a stick with a hook at the end," he said. "We've made some modifications over time because we were getting pricked by these starfish. It's painful." Named for their hundreds of venomous spikes, crown-of-thorns starfish have as many as 21 fleshy arms and can grow larger than a car tyre. They are typically found in such low numbers that they are not considered a problem. But sporadically populations explode in a feeding frenzy that rapidly strips the life from reefs. - 'Plague proportions ' - They spawn in "plague proportions", according to the Australian Institute of Marine Science, and are a major driver of coral loss. From the Red Sea to the Pacific Ocean, crown-of-thorns outbreaks appear to be becoming both more frequent and more severe. "Some argue that the crown-of-thorns has become chronic in the last few decades," said Rongo, talking about the reefs of the South Pacific. Scientists suspect these outbreaks are triggered by a mix of factors, including nutrients leached into the sea from agriculture and fluctuations in natural predators. But the damage they can cause is getting worse as reefs are weakened by climate change-fuelled coral bleaching and ocean acidification. "This is why it's important for us to help the reef," says Rongo. Scuba divers scour the Cook Islands' reefs for hard-to-spot starfish wedged into dimly lit crevices. Once peeled off the coral, the starfish are pierced with a thick rope so they can be dragged back up to a waiting boat. The day's haul is dumped into a plastic chest before the starfish are lugged ashore to be counted, measured and mulched for garden fertiliser. They are known as "taramea" in Cook Islands Maori, which loosely translates to "spiky thing". The volunteer divers working with Rongo and his environmental group Korero O Te Orau -- or Knowledge of the Land, Sky and Sea -- remove thousands of starfish every year. Rongo is spurred by the devastation from the nation's last major infestation in the 1990s. "I was part of that eradication effort.
