Giant fans and salt water cannons
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Marine ecologist Dr George Roff, who is studying natural coral heat adaption on the island while I’m there, says you can picture the near future of the Great Barrier Reef like so: “Imagine that every reef is a light. It’s never going to happen that the whole reef will go dark at once. But certain lights will go dim and they’ll go out. Some will come back on again. And some will just stay off forever.”
Scientists are zeroing in on the corals that are doing better – the lights that are staying on, for now – to see if their genetics could fast-track more heat-adapted larvae through “assisted evolution” to withstand rapid climate change.
A 2021 study found that the large-scale release of heat-tolerant coral, along with action against crown-of-thorns starfish, and “shading” reefs artificially from sunlight, could extend life support for the reef by one or two decades.
But none of those interventions are likely to be useful on an ecosystem the size of Japan.
“No one has ever restored even one hectare of reef with corals bred in a tank,” says coral reef authority Professor Terry Hughes from James Cook University. “Wild populations are already responding rapidly to climate change in favour of hardier corals that are more tolerant of heat. Adding a few more artificially bred corals is literally a drop in the ocean.”
Local solutions to “save” the reef have often wandered into the outlandish. In 2017 a $2.2 million government grant funded a trial of eight giant underwater fans designed to draw up cool water from the deep and distribute it across shallow-water corals. By 2020 the project had been quietly shelved.
Trials continue, though, for marine cloud brightening, another rather radical solution. Scientists have tested spraying salt water from cannons into the atmosphere over the ocean, which causes more water to condense in the air, producing white clouds that reflect more heat and light. There’s no real-world data that proves the technique could protect coral.
One of the Great Barrier Reef’s 3000 reefs from above.Credit: Janie Barrett
Is this work merely fiddling with a fire blanket while the city burns down? Many have long argued such interventions are a convenient distraction from tackling the climate crisis directly. Case in point: Qantas sponsored coral restoration work in 2024. In the same year it produced 17.6 million tonnes of carbon dioxide, equivalent to 4 per cent of Australia’s total annual emissions.
As politicians hit the campaign trail ahead of the federal election, Hughes is sceptical they’re prepared to reckon with reality.
“Bleaching and mass mortality of corals along the length of the GBR in 2024 was the worst we have ever seen. Federal government agencies have been very slow to reveal the extent of losses of corals, particularly on the southern region which was devastated,” he says.
“This summer, the northern GBR and major reef systems in WA both suffered major coral bleaching – and again it was independent scientists who highlighted the impacts of the record-breaking heat,” he says.
“It should be an election issue but both sides of politics are desperately avoiding the critical issue of climate change.”
How the reef feeds us
There are many reasons the reef should be saved, not least because it’s one of the most spectacular, ecologically rich, soul-capturing megastructures in humanity’s care. But a recent study highlighted a specific example of how the reef supports human nourishment.
Dr Jeff Leis, a senior fellow with the Australian Museum, began studying the larvae of coral trout in the ’90s.
“We began to understand that really they’re quite capable little animals and begin to have really meaningful behavioural capabilities quite early,” he says. “Many of them swim a kilometre in an hour.”
Lizard Island Research Station director Emily Howells snorkels above a healthy section of the Great Barrier Reef metres away from a stressed section off Lizard Island.Credit: Janie Barrett
That discovery led to better modelling of larval movement across the reef. Leis has argued for decades that creating more protected areas would boost fish numbers elsewhere – including in commercial fishing areas – because more larvae would flow from healthy reefs where “big mumma” fish are protected from capture.
And a Science Advances paper just backed up his theory, finding one of every two coral trout caught in commercial fishing zones on the Great Barrier Reef comes from larvae produced on the no-take reefs. It’s a win-win for environmental protection and for people who depend on the reef for their livelihood – of which there are at least 64,000.
But for Pessina, the wrasse-chasing researcher, it’s not just about people.
Letizia Pessina between dives during her research at Lizard Island.Credit: Janie Barrett
She’s studying the soap opera lives of cleaner wrasse: how they cultivate relationships with the “clients” they eat parasites off, and why they sometimes cheat, biting off a chunk of tasty fish mucous, risking an angry customer.
Males battle mouth-to-mouth in furious “kissing” fights, and if the dominant male dies, a female changes sexes and takes his place.
“People ask, ‘Why do you study fish? Isn’t it more important to study diseases and cancer?’” Pessina says. “But when you learn about their social system, how peculiar they are, how strategic they are … it really helps us understand the impact we have on all these organisms in the world.
“It helps, at least to my eyes, to open up and understand that not just humans matter.”
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