Doing whatever it takes to rehabilitate the Great Barrier Reef

How about saving the Great Barrier Reef with a one-molecule-thick layer of natural calcium carbonate that floats on the sea surface and reduces the damaging heat of the sun on corals? Maybe the answer is cloud-brightening — spraying microscopic droplets of seawater into the atmosphere to form clouds and provide more shade for the heat-battered reef? Perhaps we need to populate endangered reefs with more heat-resistant corals by manipulating spawning routes? Or is the answer a probiotic or nutrient — something that changes coral’s microbe communities to help them survive and recover after a marine heatwave?

All of these ideas and many more, ranging from the conservative to the wildly imaginative, are under the microscope of dozens of scientists at the Reef Restoration and Adaptation Program based at the Australian Institute of Marine Science outside Townsville in far north Queensland.

After the effects on the reef of two disastrous back-to-back bleaching incidents in 2016 and last year were first understood, and images of whitened deserts of dead coral streamed across the world’s media, the Australian government turned to science. In 2016, the worst bleaching ­occurred in the northernmost section of the reef between Port Douglas and the Torres Strait. Aerial and underwater surveys revealed 93 per cent of individual reefs were affected. In March last year it happened again: a marine heatwave killed or damaged significant parts of the reef.

The RRAP scientists have ­zeroed in on how science can boost the reef’s resilience, and they need answers quickly — the next hot season is just months away.

The size of Italy or Japan, the Great Barrier Reef runs for 2300km, from the sea south of Bundaberg up to the Cape York Peninsula. The largest living ­structure on Earth, it has been treasured for generations by Australians — most of whom (up to 90 per cent according to some surveys) value it highly.

Besides its ecological value, the reef is a multi-billion-dollar economic asset, with a value-added contribution to the Australian economy of about $6.4 billion a year. It supports 64,000 jobs and its overall economic and social value has been conservatively estimated at about $56bn by Deloitte Access Economics.

Funding to the tune of $6 million over 18 months, to June next year, has been channelled into the first stages of RRAP research on how best to boost the reef’s resilience to help it cope with ever-warming global temperatures, part of Australia’s substantial commitment to the reef. More than $500m has been announced in reef funding this year, including $100m for research into coral ­resilience and adaptation. The RRAP’s work will help inform how and where these funds are spent.

The RRAP’s measures must be affordable, risk-assessed and socially and ethically acceptable. The research will potentially ­expand to meet the problems, and some experts believe it could provide the foundation for a recovery plan that could cost billions each year in the future.

While it is widely accepted that global warming is the main cause of the reef’s ills, closely followed by inadequate water clarity from ­onshore run-off, both of these are beyond the remit of the RRAP scientists. Climate change is a terrifyingly enormous global issue, debated at the highest levels of government, and water clarity, too, requires high-level policy ­action and intervention.

Reef water quality has improved in recent years, according to the experts, but it remains a problem in some areas, particularly in the inshore reefs affected by flood plumes. Still, water ­experts are grappling with this, and how best and most economically to deal with it.

The reef, this vastly important living thing, is mortally wounded and scientists are coming to grips with how to stave off further damage. A symposium of experts from Australia and abroad, from Hong Kong, the Seychelles, Fiji, the Maldives and others, begins today in Cairns as a way of comparing and sharing ideas on reef restoration.

The convener of the symposium, Damien Burrows, who is also the leader of the Tropical Water Quality Hub in the Nat­ional Environmental Science ­Program, says the traditional ­approach to the reef has been to manage it but too let nature repair any damage at its own pace.

The pertinent reef science, to date, has been largely focused on measuring and describing the ­effects of various threats — bleaching, cyclones, water quality — as well as dealing with the coral-eating crown-of-thorns starfish.

Until recently, reef-restoration research has been lacking, he says, and “now there’s a bit of a rush to catch up”.

The past couple of years have seen intense reef research activity, Burrows says, and the symposium will give reef scientists a chance to explore the latest thinking on restoration, discuss potential avenues and share the best ways of achieving certain ends, particularly coral recovery, as well as coping with the crown-of-thorns starfish, which remains ­labour-intensive and expensive.

These days the reef management approach is far more interventionist. Scientists are consider­ing ways of artificially accelerating natural processes of reef recovery and mitigating the effects of heatwaves and other threats.

A researcher growing coral at the Australian Institute of Marine Science. Picture: Christian Miller.
A researcher growing coral at the Australian Institute of Marine Science. Picture: Christian Miller.

“There’s a rush now to redirect scientific research into these ­solution-oriented type programs, which we haven’t had a lot of,” Burrows says. “This symposium will be one of the first where you’ll see scientists focusing on ­solutions and showing that there is some hope.”

One contentious idea is to ­determine which individual reefs have the most ecological and tourism importance and direct most resources to protecting them, while triaging off the remaining reefs. Reef tourism is highly concentrated in a few locations, Burrows says, and certain reefs are priority sites ecologically. “A small number of sites can manage with mitigative technologies (to lessen the impacts of various threats). I think that’s pretty exciting as well. I believe in the power of science in finding solutions.”

One important element of the recovery program is to determine what people really want: ranging from fishing operations to tourism operators and tourists themselves, to the locals, the traditional landowners and the Australian public more broadly. And it’s not only whether people believe an effort should be made to save the reef, but how much they think should be spent on it.

Bruce Taylor, from CSIRO, is leading the stakeholder and community engagement elements of the RRAP program. A social scientist, he says he and his team have begun talking to the interested parties and a national phone and online survey is under way to canvas broader community views.

“Each of the groups has things they want to protect and things they care about, but they also have different views about how resilient the reef is, whether we should be leaving nature alone to heal itself, or whether we should be intervening directly with new types of ­technologies and different actions,” Taylor says

“We need to consider what the Australian public wants, but also perhaps we need to consider, perhaps more closely, those who earn their livelihoods from the reef, and those who have traditional or perhaps custodial responsibilities ­toward the reef.”

David Mead, who is leading the design phase of the RRAP, says ­although the reef has taken a battering in recent years, “there are still bits of it that are beautiful and resilient. It’s not down and out.” The RRAP scientists, he says, are not only considering a range of possible fixes, they also have to consider that even if they could be used, whether they should be.

He has brought in a range of ­experts to work out what to do, how to do it, and when. Engineers, social scientists, modellers, statisticians and regulatory experts are working with marine scientists to determine what is feasible and ­affordable. The scientists are working on concept feasibility studies, considering 15 categories of potential interventions.

Reef systems mostly live through disasters, get damaged and then recover, and then the cycle begins again, Mead explains. The trouble with the back-to-back bleaching of the reef in 2016 and last year was the lack of time the reef had to recover before the next deadly heatwave. Water quality, too, can affect the speed of recovery. Some of the corals can take 10 or 15 years to grow.

Coral at the Australian Institute of Marine Science Seasim lab. Picture: Christian Miller
Coral at the Australian Institute of Marine Science Seasim lab. Picture: Christian Miller

Over the past 30 years there have been disasters and recoveries, but each disaster left the reef a little more damaged, Mead says. “So there was a progressive ­decline, and it hasn’t been helped by the most recent bleaching events,” he says. And with global warming, “the trajectory is not looking good”.

RRAP scientists, naturally, have to consider a range of possible temperature trajectories — from one, two, three or even four degrees of warming.

“Where the reef will go in the future will, in a large part, depend on the specific climate trajectory that the planet follows,” Mead says. “There’s a large degree of ­uncertainty around that because it largely depends on the rate of CO2 mitigation measures.”

The scientists have an extensive modelling process to determine which ideas have the most value for various subsets of future possible temperatures.

Smaller-scale measures under consideration by some agencies include the localised shading of key reefs, possibly even with shade cloths, localised water movement with underwater fans to bring up cooler water, and coral gardening — transplanting coral to damaged reefs. But mostly the RRAP scientists have been working on measures that can be scaled out to the entire reef, helping it not just to ­recover but to adapt to a changing environment.

Aquaculture, or the farming of marine organisms, could be used, for instance, to help repopulate damaged reefs with farmed coral. “As part of the consortium, we’ve brought in engineering companies to do some concept designs for some fairly significant-scale aquaculture programs,” Mead says. “At the moment we’re looking at an aquaculture facility just to test how big it could be and how much it would cost to run so that it could produce 100,000 juveniles — one-year-old corals — every day.”

The Barrier Reef is a natural wonder of ecological diversity, and minute genetic variations in certain corals make them more or less heat-resistant. Harnessing these variations could prove to be the saviour of the reef. Efforts concentrated on seeding the “spawning reefs”, the nurseries of the entire system, could eventually spread broadly.

Coral larvae, Mead says, typically migrate southward, drifting on the reef’s prevailing currents, and there is some potential in the notion of collecting coral spawn slicks and moving them further south to harness their existing genetic potential to cope with heat stress.

Mead will not eliminate any potential measures just yet, nor will he endorse any particular project. Wary of potential unforeseen consequences, he says: “You intervene when the risk of doing ­nothing is greater than the risk of doing something.”