Ningaloo and Great Barrier Reef hit by ‘profoundly distressing’ simultaneous coral bleaching events

 Footage shows coral bleaching on Ningaloo reef as Great Barrier Reef hit at the same time – video

 Scientists say widespread damage to both world heritage-listed reefs is ‘heartbreaking’ as WA reef accumulates highest amount of heat stress on record

 Graham Readfearn

Great Barrier Reef

 Ningaloo
 

 

Australia’s two world heritage-listed reefs – Ningaloo on the west coast and the Great Barrier Reef on the east – have been hit simultaneously by coral bleaching that reef experts have called “heartbreaking” and “a profoundly distressing moment”.

Teams of scientists on both coasts have been monitoring and tracking the heat stress and bleaching extending across thousands of kilometres of marine habitat, which is likely to have been driven by global heating.

 

On the Great Barrier Reef, bleaching is being detected from around Townsville to the tip of Cape York, a distance of about 1,000km.

On Western Australia’s famous Ningaloo reef, waters have accumulated the highest amount of heat stress on record during an extended marine heatwave that has hit coral reefs all along the state’s vast coastline.

Paul Gamblin, the chief executive of the Australian Marine Conservation Society, said history would “record this profoundly distressing moment” when two world famous reefs both suffered widespread damage at the same time.

Corals begin to bleach at about 4DHW, and 8DHW can kill heat-sensitive corals. Scientists say levels up to 16DHWs have been detected on the Ningaloo coast. Photograph: David Juszkiewicz/Curtin University

Dr Zoe Richards, an associate professor and coral scientist at Curtin University, spent 10 days monitoring the health of Ningaloo reefs and the neighbouring Exmouth Gulf earlier this month.

She said in shallower areas known for their clear waters, which are popular with tourists, she had seen up to 90% of corals bleached and evidence of corals dying. Even slow-growing corals that were hundreds of years old were bleaching, she said.

Ningaloo last experienced widespread bleaching only three years ago.

 

The WA government, which is coordinating monitoring across reefs there, said bleaching had also been reported at Kimberley, Ashmore Reef, Rowley Shoals, Barrow Island, Dampier Archipelago, inshore Pilbara and Exmouth Gulf.

Richards said: “This isn’t isolated to Ningaloo – this is happening across the entire north-west shelf. There has never been this scale of impacts in WA. I am not aware of this ever happening before. Climate change has definitely caught up with the reefs in WA.”

Corals lose the algae that give them their colour and most of their nutrients if ocean waters get too warm. If bleaching is not severe, corals can recover, but studies show they are less able to reproduce and are more susceptible to disease.

Coral reef experts use a metric known as degree heating weeks (DHW) to show how much heat corals have accumulated. Generally, corals begin to bleach at about 4DHW, and 8DHW can kill heat-sensitive corals.

Dr Jessica Benthuysen, an oceanographer at the Australian Institute of Marine Science (Aims), first saw signs of heat accumulating in WA last August. By the end of December, she said, some areas had sea surface temperatures 4C hotter than normal.

Benthuysen said levels up to 16DHWs had been detected on the Ningaloo coast, which were the highest on record.

Bleaching at Lakeside Reef Front, Ningaloo. Paul Gamblin of the AMCS says scientists have warned of widespread damage from underwater heatwaves and cyclones to both reefs ‘for decades’. Photograph: Zoe Richards/Curtin University

Coral bleaching at Mesa Back Reef at Ningaloo in WA. Photograph: Chris Fulton/Australian Institute of Marine Science

The US government’s Coral Reef Watch says DHWs between 12 and 16 are enough to cause coral death across multiple species.

The federal government’s Great Barrier Reef Marine Park Authority has coordinated monitoring flights over northern reefs, finding low to high levels of bleaching on most reefs. Underwater checks found bleaching at 24 of 30 reefs surveyed.

Bleaching was worse farther north – there is no concern for reefs in the park’s southern section.

Last summer was the worst bleaching event on record for the reef and the fifth major outbreak in eight years, hitting all across the marine park.

Dr Neal Cantin, a coral reef biologist at Aims who was on the monitoring flights, said bleaching was generally worse closer to shore but there was “high to medium” bleaching on reefs from Cairns to the far north. He said in the far north, heat stress was between six and 13DHWs, which was “capable of causing mortality”.

Dr Roger Beeden, the chief scientist at the authority, said detailed analysis of the data from the flights was still being analysed, but he said the lack of recovery time for corals between major events was worrying.

“It’s the frequency as well as the severity that makes us most concerned,” he said.

Dr Emily Howells, a coral scientist from Southern Cross University who has been at the Australian Museum’s research station on Lizard island since February, said this was now the sixth summer in a row that bleaching had been seen there.

The island, in the north of the reef, was badly hit by bleaching last summer and scientists at Aims who visited in subsequent months said the area had lost one-third of its live corals due to the heat.

Howells said there was less coral mortality this year, “but that’s because a lot of the sensitive corals died last summer”.

“There just isn’t enough opportunity for these coral communities to bounce back. It’s heartbreaking,” she said.

“We’re making it more and more challenging for the corals. The solution is having stronger action on climate change. The longer we wait, the worse it will get.”

 

Northern parts of the Great Barrier Reef have also been heavily affected by flooding from torrential rains. James Cook University’s TropWATER group has recorded flood waters carrying sediments and nutrients in a plume across 700km of the coast and extending as far as 100km offshore.

Jane Waterhouse, a reef water quality expert at TropWATER, said major flood events appeared to be happening more often and flood plumes were reaching farther offshore.

“River discharge carries pollutants, sediments and nutrients,” she said. “You get muddy water that cuts the light that seagrass and corals need to grow, and that nutrient also allows algae to grow.”

Gamblin said the widespread damage from underwater heatwaves and cyclones to both reefs was “what our world-renowned scientists have been warning us about for decades”.

He said fossil fuel companies were “doubling down” to get more mega projects running, pointing to areas around Scott Reef in WA being targeted for expansion by Woodside.

He said: “More mega polluting projects up at places like Scott Reef will make a tragic situation worse. What will our children say to us?”

 

 

‘Catastrophic’: Great Barrier Reef hit by its most widespread coral bleaching, study finds

 

Rising water temperatures began to turn the corals of One Tree Island reef white in early 2024. Photograph: Sydney University

 

 More than 40% of individual corals monitored around One Tree Island reef bleached by heat stress and damaged by flesh-eating disease

 

More than 40% of individual corals monitored around a Great Barrier Reef island were killed last year in the most widespread coral bleaching outbreak to hit the reef system, a study has found.

Scientists tracked 462 colonies of corals at One Tree Island in the southern part of the Great Barrier Reef after heat stress began to turn the corals white in early 2024. Researchers said they encountered “catastrophic” scenes at the reef.

Only 92 coral colonies escaped bleaching entirely and by July, when the analysis for the study ended, 193 were dead and a further 113 were still showing signs of bleaching.

 

Prof Maria Byrne, a marine biologist at the University of Sydney and lead author of the study, has been researching and visiting the island for 35 years.

“Seeing those really massive colonies die was really devastating,” she said. “I have gone from being really sad to being really cranky. We have been trying to get the message across about climate change for ages.”

 

 

Shows mass coral bleaching on Great Barrier Reef amid global heat stress event 

 

In November the Australian Institute of Marine Science visited eight reefs in the same Capricorn-Bunker sector of the reef. They found the single largest annual decline in hard coral cover in that area since monitoring started in the mid-1980s, with coral cover dropping by 41%.

Similar falls in coral cover were also recorded by Aims scientists in parts of the northern section of the reef, where one government scientist has described seeing a “graveyard of corals”.

Corals at One Tree Island reef have suffered also from a flesh-eating disease known as black band. Photograph: Sydney University

Byrne and colleagues set up the study in early February last year. The team used temperature loggers, video and direct observations to track the welfare of 12 different types of coral.

The scientists wrote in the study: “As corals can recover from mild bleaching when water cools, there is a perception that while bleaching is bad, it is not necessarily catastrophic. What we observed at [One Tree Reef] was by contrast, catastrophic.”

One genus of coral – Goniopora, which is long-lived and forms large boulders covered by vibrant flower-like polyps – was observed bleached and then afflicted with a flesh-eating disease known as black band.

Byrne said it was the worst bleaching recorded at One Tree reef. The corals that were still white at the end of their study could recover, or could die, she said.

 

Dr Shawna Foo, a coral reef scientist at the University of Sydney and study co-author, has worked on the island for several years but said that after tracking the corals for five months “it was hard to recognise” many of the colonies, because they were either “covered with algae, dead or crumbling”

“It’s horrible to see this happen to somewhere I know really well but we were expecting this to happen because we have seen it in other parts of the reef, and other parts of the world,” she said.

March is usually the peak month for heat stress on the reef. The Great Barrier Reef Marine Park Authority said last week temperatures were currently up to 1.2C above average across most of the marine park.

 Great Barrier Reef suffering ‘most severe’ coral bleaching on record – video

 

The US government’s Coral Reef Watch program is projecting parts of the reef, north of Cooktown, will be subjected to heat stress and potentially more widespread bleaching by mid-February.

Richard Leck, the head of oceans at WWF-Australia, said: “We are yet to see the full data about last summer’s coral bleaching, but it’s clear there has been major mortality in areas from the north and this new research shows major mortality in the south.

“The reef is under more heat stress this summer, especially in the north, and there’s a risk we could see another back-to-back bleaching event. It’s a case of Russian roulette whether that occurs or not.

“We know the reef is under increasing pressure from climate change and its world heritage status is under increasing pressure.”

The Australian government has been asked by Unesco to report on the condition of the reef by early next month, and Leck said it was “vital an accurate representation of the reef’s health is given, and new and increased efforts to protect the reef are committed to”.

 

Climate-Related Death of Coral Around World Alarms Scientists

                                         

NYtimes 

SYDNEY, Australia — Kim Cobb, a marine scientist at the Georgia Institute of Technology, expected the coral to be damaged when she plunged into the deep blue waters off Kiritimati Island, a remote atoll near the center of the Pacific Ocean. Still, she was stunned by what she saw as she descended some 30 feet to the rim of a coral outcropping.

“The entire reef is covered with a red-brown fuzz,” Dr. Cobb said when she returned to the surface after her recent dive. “It is otherworldly. It is algae that has grown over dead coral. It was devastating.”

The damage off Kiritimati is part of a mass bleaching of coral reefs around the world, only the third on record and possibly the worst ever. Scientists believe that heat stress from multiple weather events including the latest, severe El Niño, compounded by climate change, has threatened more than a third of Earth’s coral reefs. Many may not recover.

Coral reefs are the crucial incubators of the ocean’s ecosystem, providing food and shelter to a quarter of all marine species, and they support fish stocks that feed more than one billion people. They are made up of millions of tiny animals, called polyps, that form symbiotic relationships with algae, which in turn capture sunlight and carbon dioxide to make sugars that feed the polyps.

An estimated 30 million small-scale fishermen and women depend on reefs for their livelihoods, more than one million in the Philippines alone. In Indonesia, fish supported by the reefs provide the primary source of protein.

“This is a huge, looming planetary crisis, and we are sticking our heads in the sand about it,” said Justin Marshall, the director of CoralWatch at Australia’s University of Queensland.

Bleaching occurs when high heat and bright sunshine cause the metabolism of the algae — which give coral reefs their brilliant colors and energy — to speed out of control, and they start creating toxins. The polyps recoil. If temperatures drop, the corals can recover, but denuded ones remain vulnerable to disease. When heat stress continues, they starve to death.

Damaged or dying reefs have been found from Réunion, off the coast of Madagascar, to East Flores, Indonesia, and from Guam and Hawaii in the Pacific to the Florida Keys in the Atlantic.

The largest bleaching, at Australia’s Great Barrier Reef, was confirmed last month. In a survey of 520 individual reefs that make up the Great Barrier Reef’s northern section, scientists from Australia’s National Coral Bleaching Task Force found only four with no signs of bleaching. Some 620 miles of reef, much of it previously in pristine condition, had suffered significant bleaching.

In follow-up surveys, scientists diving on the reef said half the coral they had seen had died. Terry Hughes, the director of the Center of Excellence for Coral Reef Studies at James Cook University in Queensland, who took part in the survey, warned that even more would succumb if the water did not cool soon.

     

                                   

“There is a good chance a large portion of the damaged coral will die,” he added.

Scientists say the global bleaching is the result of an unusual confluence of events, each of which raised water temperatures already elevated by climate change.

In the North Atlantic, a strong high-pressure cell blocked the normal southward flow of polar air in 2013, kicking off the first of three warmer-than-normal winters in a row as far south as the Caribbean.

A large underwater heat wave formed in the northeastern Pacific in early 2014, and has since stretched into a wide band along the west coast of North America, from Baja California to the Bering Sea. Nicknamed the Blob, it is up to four degrees Fahrenheit warmer than surrounding waters, and has been blamed for a host of odd phenomena, including the beaching of hungry sea lions in California and the sighting of tropical skipjack tuna off Alaska.

Then came 2015, with the most powerful El Niño climate cycle in a century. It blasted heat across the tropical and southern Pacific, bleaching reefs from Kiritimati to Indonesia, and across the Indian Ocean to Réunion and Tanzania on Africa’s east coast.

“We are currently experiencing the longest global coral bleaching event ever observed,” said C. Mark Eakin, the Coral Reef Watch coordinator at the National Oceanic and Atmospheric Administration in Maryland. “We are going to lose a lot of the world’s reefs during this event.”

Reefs that take centuries to form can be destroyed in weeks. Individual corals may survive a bleaching, but repeated bleachings can kill them.

Lurid reports of damaged reefs started coming in from worried scientists in the summer of 2014.

Lyza Johnston, a marine biologist in the Northern Mariana Islands, dived to the reefs off Maug, a group of small islands: “In every direction, nearly all of the corals were bright white.”

Misaki Takabayashi, a marine scientist at the University of Hawaii at Hilo, surfed the waves above the blue rice coral there: “I could see what looked like bleached white ghosts popping up off the ocean floor at me.”

Cory Walter, a senior biologist at the Mote Marine Laboratory in Florida, peered down from a boat over Wonderland Reef off the Lower Florida Keys: “It almost looks like it snowed on the reef.”

Predicting the duration of the bleaching or forecasting the next one is difficult. The Blob has cooled somewhat, and El Niño, while weakening, is expected to stretch into 2017.

Dr. Eakin, the coral-reef specialist at the National Oceanic and Atmospheric Administration, said he expected the bleaching to continue for nine more months. Scientists will not be able to measure the full extent of the damage until it is over.

         

                                       

What is clear is that these events are happening with increasing frequency — and ferocity. The previous bleachings, in 2010 and 1998, do not appear to have been as extensive or prolonged as the current one.

The 1998 bleaching, which Dr. Eakin said had been set off by a fierce El Niño, killed around 16 percent of the world’s coral. By 2010, oceans had warmed enough that it took only a moderate El Niño to start another round.

Then in 2013, Dr. Eakin said, “a lot of bleaching happened due to climate change, before the El Niño had even kicked in.”

Reefs that were bleached in 2014, like those in the Florida Keys and the Caribbean, had no time to regenerate before suffering further thermal stress from El Niño last year, leaving the coral vulnerable to disease and death.

The reefs in the Florida Keys “are about to go into a third year straight of bleaching, something that has never happened before,” said Meaghan Johnson, a marine scientist at the Nature Conservancy. “We are worried about disease and mortality rates.”

Ove Hoegh-Guldberg, the director of Australia’s Global Change Institute, noted that 2015 was the hottest year ever recorded, both on land and in the oceans — breaking a record set just the year before.

“Rising temperatures due to climate change have pushed corals beyond their tolerance levels,” he said, adding that back-to-back bleaching can be particularly deadly to the corals.

El Niño warms the equatorial waters around Kiritimati Island more than anywhere else in the world, making it a likely harbinger for the health of reefs worldwide. That is why Dr. Cobb, the Georgia Tech scientist who made the recent dive, has been making the trek at least once a year for the past 18 to the tiny atoll, part of the Line Islands archipelago.

Though the atoll sits just north of the Equator, trade winds suck water up from the depths of the ocean, usually keeping the water temperature surrounding the reefs a healthy, nearly constant 78 degrees.

But in 2015, the expected upwelling of deep, cold water did not happen, Dr. Cobb said, speaking by satellite phone after her dive. So water in the atoll was 10 degrees warmer than normal, and never cooled enough to allow coral to recover.

“The worst has happened,” she said. “This shows how climate change and temperature stresses are affecting these reefs over the long haul. This reef may not ever be the same.”