Selective breeding doubles heat tolerance of Ningaloo Reef coral, study finds

Australia Broadcast Center

08-06-2025

Unnatural selection has bred life in all shapes and sizes, and a globe-spanning team of scientists says the same practice might help save Western Australia's Ningaloo Reef.
Mining billionaire Andrew "Twiggy" Forrest will share that finding at the United Nations Ocean Conference this week, after research backed by his philanthropic Mindaroo Foundation discovered that selective breeding could harden certain Indian Ocean corals against rising ocean temperatures.
Kate Quigley, a molecular ecologist at the foundation's Exmouth laboratory, led the study.
She said years of selective breeding trials had shown great promise for protecting the World Heritage site from coral bleaching.
In the past summer alone, the reef faced widespread damage amid a record-breaking marine heatwave.
But by manipulating its annual coral spawn, researchers claim they have confirmed a long-held hope.
The new study re-engineers techniques first developed at the Great Barrier Reef.
Samples of two Acropora coral species were taken from two sections of the Ningaloo Reef, separated by more than 100 kilometres.
"We collected parent corals, so 'mum' and 'dad' corals from an on-average hot reef," Dr Quigley said.
"Then, we also went down south to the southern part of Ningaloo Reef and collected what we call 'cool' parents.
Alexandra Kler Lago, a master's student from the University of Bremen in Germany, said coral "matchmaking" came with "some pressure".
Transporting fragile organisms from the southern tip of the world's largest fringing reef required a specially designed boat.
"We had to develop these coolers with a pumping system to keep the water at a stable temperature," Ms Kler Lago said.
Although the journey from the reef's more accessible northern colonies was passable by road, that too brought challenges.
"We actually had to go to the shallow part with buckets and then carry them filled with water to the trucks," she said.
The white-knuckle drive home aside, the breeding process was ultimately an exercise in extreme patience.
"All the spawning happens at night, so if we shine a big bright light, that might disturb and hinder the whole process," Ms Kler Lago said.
"We have to watch, look at buckets for hours, and look at specific cues that can tell us that breeding is imminent.
When "the big night" arrived, Dr Quigley described sorting gametes, or egg and sperm bundles, into groups and allowing them to produce offspring.
"We reared up these baby corals to essentially become teenager corals, and we put them through a stress test," she said.
Repeated experiments suggested Acropora tenuis, a structural coral found throughout Ningaloo, with at least one "hot" parent and particularly a 'mum' possessed twice the ability to survive temperatures of 35.5 degrees Celsius than other genetic combinations.
Australian Institute of Marine Science principal research scientist Chris Fulton said selective breeding was one possible solution for safeguarding the Ningaloo Reef.
"We need to protect those corals … that have been robust and have resisted this heatwave event, so they have the best chance possible to repopulate the reef with a new warm-adapted … more resilient coral population."
Dr Fulton returned from a trip to the World Heritage site earlier this month.
He said water temperatures were only now beginning to drop.
"This is the first time we've seen every part of the WA coast show signs of coral bleaching … it has been so hot for so long, over such a large scale that we obviously need to act on emissions reduction."
Dr Quigley said further research was needed before attempting to grow heat-resistant corals in vulnerable parts of the reef.
She echoed calls for carbon emissions reduction, saying conservation strategies such as selective breeding could only work "hand in hand" with climate policy.
"We absolutely need emissions reductions to happen immediately in order for these techniques to have a meaningful impact," she said.