Death becomes a coral reef.
When healthy, most corals are subtle shades of brown or green. But, under stress, many increase production of more vibrant pigments; hot pinks, vivid blues, luminous yellows, unfurling across a reef like marine fireworks.
“To put it simply, they glow,” says John Edmondson, a marine biologist who has run reef tours out of Port Douglas, in far north Queensland, since the early 1990s.
He tells of commercial photographers returning from the Great Barrier Reef during these events, raving that they have captured stunning pictures that prove this natural wonder of the world is in rude health, despite rumours to the contrary.
Edmondson doesn’t dispute the beauty of the spectacle, but to his trained eye it also looks like death – because that’s what it is. Beneath his tour boat, beneath the humpback whales frolicking around it, one of the world’s most complex ecosystems is grappling with its imminent demise.
The Great Barrier Reef is by far the largest and most diverse reef system in the world. What is happening here is a scaled-up version of the problem being experienced in tropical seas everywhere; a giant spotlighted example of a crisis that threatens not just reefs but also the life they sustain, including a quarter of the world’s marine fish and 500 million people who rely on them for sustenance.
If there is glimmer of hope, it is that the Great Barrier Reef has attracted some of the best scientists in the world, and some of the most passionate marine advocates, united in their determination to boost coral resilience.
The process by which corals show their brightest colours as they die is called fluorescence. It’s not well understood, although some scientists believe heat-stressed corals generate more pigment to act as a block against the burning rays of the sun, just as diligent swimmers apply SPF50+ sunscreen before venturing out in the tropics.
The next phase – coral bleaching – is more straightforward.
In good conditions, corals enjoy a symbiotic relationship with tiny organisms called zooxanthellae; in return for being housed within a coral’s polyps, these microorganisms capture sunlight and convert it to nutrients which feed their host. However, if external temperatures become too warm, they begin to produce toxic levels of oxygen, prompting the corals to expel them in what is a potentially suicidal act.
Without the zooxanthellae, the coral’s living tissue becomes clear, exposing the hard white skeleton underneath.
“That’s the most dramatic stage,” Edmondson says. “It can seem almost beautiful too, everything pure white.”
Even at this point, there is hope. If external conditions improve quickly enough, most corals will welcome zooxanthellae back to begin photosynthesising again. But if temperatures remain elevated over several weeks – an average of 1 degree Celsius above average for eight weeks, is the general rule of thumb – the bleached corals are likely to starve to death.
There is no beauty in the graveyard left behind.
Mother Nature has no time for grief. A living coral reef might have provided a rich habitat for thousands of species of fish and other marine creatures. But, once dead, it is simply another part of the food chain. Decomposing coral polyps are an excellent fertiliser for turf algae and seaweed; within weeks, the reef will be blanketed in green and brown slime.
In 2016, Richard Vevers, founder and CEO of the Ocean Agency, captured pictures of this gut-wrenching process off Lizard Island, a further 200km north of Port Douglas, while documenting one of the worst mass bleaching events on record. The photographs quickly went viral.
“The soft corals were just decomposing – animals literally dripping off the rocks,” Vevers told the Guardian. “The most horrifying part was that we just absolutely stank of rotting animals [when we came up from the dive]. That’s when you really realise that reefs are made up of billions of animals.”
In other areas of the northern Reef, the temperatures rose so quickly, the corals had no time to bleach. They died as they were, in water that was cooking them.
At 2,300km long and roughly the size of Japan, the Great Barrier Reef is the largest living structure on the planet, dwarfing the next largest reef, off Belize in the Caribbean, by a scale of almost eight to one. Given its massive size, it is somewhat surprising that the Reef was spared the worst bleaching for most of last century, even as average temperatures climbed and bleaching elsewhere became more frequent and more severe.
But, in 1998, that run of luck ended abruptly. An extreme El Niño triggered a global bleaching event that smashed scientific records and challenged conventional wisdom. Roughly half of the corals on the Great Barrier Reef were damaged, mainly in the southern and central regions.
Reefs usually need 10-15 years to recover naturally from damage on that scale. The Great Barrier Reef got four. In 2002, it suffered an even more extreme bleaching event, with up to 70 per cent of corals dying in some areas. Ominously, 2002 was not even an El Niño year, but part of a La Niña phase, usually associated with milder conditions.
Then, in 2016 and 2017, the reef suffered the first back-to-back bleaching events on record anywhere in the world.
It began in February 2016 with a series of hot, still days, the sort that enthralled snorkellers touring the reef on Edmondson’s boats.
When the conditions hadn’t eased by March, Edmondson decided to visit SNO, one of Opal’s prettiest spots, with its extensive gardens of plate coral, and schools of fish enjoying a healthy current. It would be the last time he enjoyed the spectacle. Ultimately, about two thirds of the coral in the northern Great Barrier Reef would die in 2016-17.
Four-hundred kilometres to the south, Dr Line Bay pauses on the threshold of the nursery.
The room reverberates with muted gurgling as our eyes adjust to the dim light.
The babies here are lined up in orderly rows, the details of their arrival and specific needs recorded in bright markers for the staff who track their progress.
Some are plump and flushed with health. Others throw out tiny limbs, already exploring the world around them. But there are also plenty that seem stunted and wan, and some that are barely more than skeletons.
Bay is equally intrigued by those that are thriving as those failing. The infants here at the Australian Institute of Marine Science (AIMS) are corals, not humans, and their progress in a variety of settings imposed upon them in laboratory conditions may shed light on what can be done to boost the resilience of the Great Barrier Reef – and corals around the world – as the planet warms.
As leader of the Reef Recovery, Adaptation and Restoration team, Bay oversees experiments spread through AIMS’s National Sea Simulator, a world-leading research facility that sits on the coast about 50km from Townsville.
Every day, “SeaSim” pumps more than 800,000 litres of seawater from the nearby Coral Sea – hence the pervasive sound of gurgling – to help scientists carefully calibrate the conditions in tanks holding hundreds of corals from more than 20 species.
“We call it the smartest aquarium in the world,” Bay says. “We can simulate the Reef in almost real time from where these corals were collected, and then we can add other variables like temperature and CO2 mix, and even to match the daily and seasonal variations in light.
“We are asking the question: can we assist evolution and help corals become more heat-tolerant more quickly?”
She stops by a series of tanks in which corals have been growing for almost three years, some at present day temperatures, some at the projected mid-century conditions of +1C degree, and others in an end-of-century scenario set at +2C degrees. The tanks can also be adjusted to reflect lower pH levels, as warming seas retain more CO2 and become more acidic. The decline in the number of live corals, and the relative health of the survivors, between the tanks is unnerving.
Bay agrees: “It’s visually striking – and there’s no doubt in the scientific community that climate change is not good for corals. But… corals are individuals and you also get big variations. Some are not very happy at all, but there are some that are just fine.
“That’s one thing that gives me a lot of hope. Variation is fuel for natural adaptation. And if there’s potential for natural adaptation, there’s also potential to help nature a bit.”
Specifically, Bay’s team and colleagues are hoping to “help nature” through what is referred to at AIMS as “assisted evolution”.
“We are really looking at understanding heat tolerance in all its glory,” Bay explains, “How it’s affected by genetics, by the environment, how it’s inherited. With that knowledge, you can then take it one step further: we aim to breed [heat-tolerant] corals in the lab and, if that’s promising, move forward to very contained field trials and after that potentially to a larger scale.”
The scientists are aided in their research by the fact that corals boast an eye-popping array of reproductive predilections.
“Whatever mode you can think of, you’ll find a coral that can do that,” Bay explains. “Pretty much anything goes.”
Many corals are hermaphrodites and, for most of the year, will reproduce asexually through fragmentation, if at all. If broken off during wild weather, or by fish grazing for algae, coral fragments may grow into a clone of the parent, provided they are fortunate enough to land in hospitable conditions.
Alternatively, many GBR corals also spawn once a year, in a window of a few days after the full moon in October or November. During that period, wild corals release bundles of sperm and eggs into the ocean, where they may drift for kilometres before settling. SeaSim replicates natural conditions so closely that some of its lab corals spawn in sync with those in the wild, sparking several hours of frenzy for researchers who collect the spawn for use in their research.
Last year, Bay’s fitness tracker reported she covered 15km during spawning at SeaSim, as she hurried to collected bundles of sperm and eggs to be separated for experiments.
Bay’s own research focuses on cross-breeding more resilient corals from northern reefs in the Great Barrier Reef with populations of the same species in the cooler south. “Adaption to climate change could happen naturally, with those heat-tolerant individuals making their way down the reef,” she explains. “But our models are showing that is likely to happen too slowly to respond to the rapid changes we’re seeing now in the environment. So we’re testing whether we can speed up the process [in the lab].”
Media reporting has often swerved into hyperbole, with publishers knowing a story about “supercorals” is more likely to attract interest than one about hybridisation or assisted gene flow.
But Bay baulks at the “supercorals” tag. She points out that it is one thing to grow new breeds of coral in controlled conditions, but another thing entirely for them to survive transplantation, and the variables they will face in the wild, including predation, wild weather and disease.
“No single intervention is going to be a silver bullet,” she says. “It will be a package [of measures] as a whole.”
She is also adamant that none of the scientific efforts will be enough to save the Great Barrier Reef if the world does not meet its Paris Agreement commitments, and limit warming to between 1.5 and 2 degrees Celsius above pre-industrial levels.
“Reef restoration isn’t about eliminating the impact of climate change,” Bay says, pausing beside a gurgling tank of coral babies. “The best we can do is soften the blow… It would be wonderful if we never had to use any of this.”
The unprecedented back-to-back bleaching events that hit the Great Barrier Reef in 2016 and 2017 were no surprise to scientists, who had been warning of the growing threat to the World Heritage-listed marine park for years.
But they did prove to be a catalyst for action from other quarters.
In January 2018, then Prime Minister Malcolm Turnbull unveiled almost $60 million in funds to protect the reef, including $6 million to establish a new Reef Restoration and Adaptation Program (RRAP), to be led by AIMS.
Politically, it was a no-brainer. Apart from its status as a World Heritage Area, the Great Barrier Reef is enormously valuable to the Australian economy. Attracting 2 million visitors annually, it generates 64,000 jobs and contributes $6.4 billion to the economy, according to a report by Deloitte Access Economics, widely circulated in the wake of the 2017 bleaching event.
Another funding injection followed in April 2018, this time of a massive $500 million, including $100 million specifically for restoration and adaption science to be conducted through RRAP.
Drawing on the expertise of more than 100 scientists from Australian and international universities, and specialists from a range of industry organisations, the program quickly gained international attention for its ambitious scope.
“It is by far the largest and most multi-institutional, multidisciplinary approach to reef restoration that the world has ever seen,” says David Wachenfeld, chief scientist of the Great Barrier Reef Marine Park Authority (GBRMPA)
“It’s an amazing collaboration of [experts in] marine science, biology, ecology, engineering, mathematics, modelling ethics and governance. It’s about looking at what is possible and being as rigorous about that as possible.
“As a reef manager, I would always like to play it safe. But we can’t play it safe any more; climate change has taken that luxury away…”
AIMS’ former chief operating officer David Mead was named to lead the programme. An engineer rather than a scientist, Mead had nonetheless won the support of many at AIMS by designing their world-class research hub, SeaSim, while he was serving in his “day job” as COO.
His first step was to assign project teams to conduct scoping studies of 160 different reef interventions. Each was assessed for scalability, projected cost and potential risks.
“We specifically said at the outset that no idea was too dumb to talk about,” Mead says, before confessing he was initially sceptical about cloud-brightening, a method in which nanoparticles of salt are blasted into clouds to enhance their capacity to reflect sunlight back into space.
Mead now believes it is one of the most promising interventions, given it is relatively low-risk, with a short half-life. Critically, it also prevents damage to coral before it occurs. A guiding principle of RRAP is that “prevention is better than cure”; artificial restoration of reefs should always be a worst-case management tool.
Other preventative measures that have been proposed include organic surface films – forms of floating sunscreen to protect coral – and giant pumps to disperse cooler water on to heat-stressed reefs, although both have been found by RRAP to be limited to small-scale use only.
New techniques and tools to aid recovery of damaged reefs are also being sought, given both bleaching and extreme weather events like cyclones are forecast to become more frequent.
“As the condition [of a reef] gets worse, the recovery takes longer, and the combination of longer recovery times with more frequent events is not great,” Mead says.
He points to Florida Keys and parts of the Caribbean as examples where reefs have been battered by multiple variables, including disease, fishing practices, pollution and, of course, bleaching, and natural coral reproduction has “crashed”.
Without intervention, when could that happen on the Great Barrier Reef? “It’s hard to predict. It will depend a lot on the particular climate scenario and the level of natural adaptation. If we’re lucky, it could be 20 years. But it could be two years.”
Having eliminated more than 110 interventions, RRAP is due to submit a feasibility plan to government. The next phase will involve more scrutiny of the remaining 40+ options, eliminating those that prove to be unfeasible, developing the most promising, and progressively deploying them over the next five to ten years.
It is an approach that has more in common with Silicon Valley, where ambitious start-ups are encouraged to “fail fast” or “move fast and break things”, than with scientific traditions of linear investigation and rigorous peer review.
And not all scientists are happy about it. One of the most vocal critics is also one of the world’s leading coral authorities, Professor Terry Hughes, who says that science is being used cynically to distract from the fact that neither of Australia’s major political parties want to act decisively to cut emissions.
“The subliminal message is that we can save the world’s reefs because scientists are so bloody clever,” says Hughes, who is the longstanding director of the ARC Centre of Excellence for Coral Reef Studies, at James Cook University in Townsville.
“But, really, what they’re doing is buying time for coral reefs while the world gets its act together and buying time for the fossil fuel industry.”
It doesn’t take long for Hughes to knock some of the gloss off the potential solutions being explored at RRAP and elsewhere.
“Reef restoration is often touted as something new and novel, but it has been tried for 50 years, and nobody has ever restored the biodiversity of a single reef,” he says. “Restoring something the size of the Great Barrier Reef would be like trying to replant the Amazon using seedlings from a greenhouse – except under water, where you can’t use a wheelbarrow and you have to hold your breath as well.”
Dr Andrew Baird, a professorial research fellow and the chief investigator at the ARC Centre of Excellence, is equally scathing, drawing on his own experience in developing countries like Indonesia, where he says he has seen “hundreds of restoration schemes fail”.
“Some of the assisted evolution work promises potentially interesting science – but good science takes time,” Baird says.
“As for reef restoration, I think it is a complete waste of money and a distraction from action on climate change. It is essentially a smokescreen to allow the Federal Government to pretend it is doing something for the reef while continuing to support the coal industry. Any scientist involved is accepting pieces of silver to betray the reef.”
Out on Opal Reef, a school of jewel-hued fish dart and scatter as John Edmondson approaches them with a hammer.
His target is actually a lunchbox that sits, somewhat incongruously, on a bare section of reef flanked by healthier patches of coral. Earlier, while snorkelling, Edmondson has collected small pieces of broken corals – known as “fragments of opportunity” – that had fallen on sand or other places where they were otherwise likely to die. They are stashed in the lunchbox, awaiting the next phase of his endeavours.
He had also harvested some corals from an underwater nursery nearby. The construction is simple: a 2m x 4m aluminium screen, of the type commonly available at hardware stores for use on household windows and doors, weighed down with concrete blocks to keep it stable in several metres of water.
The nursery is part of the Coral Nurture Program, a collaboration between tourism operators like Edmondson and scientists at the Future Reefs Program at the University of Technology, Sydney (UTS). It evolved out the scientists’ need to access existing infrastructure on the Reef, including boats, in order to run their field research, and a desire among tourism operators to do more to take care of an environment they knew intimately.
“There’s a real hunger among tourism operators to do something proactively for the Reef,” says programme leader Associate Professor David Suggett, a marine biologist.
“They don’t see it in dollar signs; they are emotionally connected to it… But, up until 2018, they weren’t allowed to repair reefs, only to remove Crown of Thorns starfish and snails [which feed on corals].”
But one of the changes sparked by the back-to-back bleaching events in 2016 and 2017 was a preparedness by the Great Barrier Reef Marine Park Authority to issue permits for localised coral out-planting, and by the state and federal governments to fund further research projects to boost coral abundance.
The operators use a patented clip designed by Suggett and his team to make the process as quick and efficient as possible, without the mess of glues that have been used elsewhere. Looking a bit like a screw with a small metal arm extending from its shaft, the clip can be nailed into substrate on a reef, and a coral fragment secured snugly beneath its arm. Held fast against currents and wave action, the fragment is then able to attach to the reef itself within a matter of days, where it will potentially flourish and eventually reproduce naturally.
Over several months in early 2018, the team stocked 10 nursery frames at Opal Reef with more than 1,500 coral fragments, made up of 10 different coral species. By the end of the year, they were able to report a 100 per cent survival rate.
“The biggest ‘wow’ moment for me so far was when I first went back to Opal Reef and John had planted about 1,000 corals,” Suggett says. “It was a real transformation.”
Suggett is adamant coral outplanting from nurseries like this is not intended to “save the Reef”.
“But even if we solve climate change tomorrow, we’re going to be dealing with a lot of residual heat in oceans for 20 years or so,” he says. “The focus [of the Coral Nurture Program] for now is looking after high value reefs… But we’re never going to understand how reliable and scalable something is unless scientists are willing to work together as a collective, with other stakeholders like operators who really want to do something.”
Edmondson believes he is doing his part, as he takes his hammer and drives the clip into the substrate with three expert taps. As he is snorkelling today, rather than wearing an oxygen tank, speed is particularly crucial; within seconds he has inserted a fragment of coral beneath the clip and kicked upward to the surface.
Treading water, he does some quick maths.
“If I go out with someone who is well practised, and I hammer the nails in and they come around behind attaching the corals, we could do 200 in an hour as a buddy pair,” he says.
“And if we came out here with four buddy pairs, and we all did four dives in a day, each pair could plant 800 corals, making it 3,200 total in a day. If you could do four days in a row, that’s 12,800 corals in a week. That would make a significant difference to a site.”
He pauses for a minute, catching his breath. Around us, the ocean stretches out on all sides to meet the pale blue dome of the sky. In the distance, it’s possible to hear waves rolling in from the Pacific Ocean and crashing on the outer edge – the actual barrier – of this Reef.
But Edmondson is too busy to contemplate the vastness. He takes a deep gulp of oxygen and disappears again into the depths.
He is, quite literally, holding his breath as Terry Hughes has described, while trying to replant his little patch of the Great Barrier Reef. As the rest of us wait for our governments to act decisively on climate change, perhaps we should all be doing the same.
Images by Australian Institute of Marine Science; David Suggett; The Ocean Agency; Coral Reef Image Bank