Researchers have crossbred coral from Western Australia's Ningaloo Reef for the first time as part of efforts to improve resilience against bleaching events caused rising water temperatures.
The "assisted gene flow" technique they used has previously been used with coral from the Great Barrier Reef.
Molecular ecologist Kate Quigley, a research director at the Minderoo Foundation's Exmouth research lab, said the experiment crossbred coral from cooler and warmer waters of the reef, with specimens from the latter potentially more hardy.
The aim was to produce tough coral offspring that could survive warming conditions.
"We wait for them to spawn — so in the middle of the night, and at a specific time per species, they release their egg-sperm bundles," Dr Quigley said.
"We can collect those bundles at the surface and then we're able to do our selective breeding, so we're able to separate the eggs and the sperm.
"By the end of the night, we have a number of different families that are produced from … crosses of different hardy coral mums and dads with more vulnerable coral mums and dads."
Finding genes for resilience
Dr Quigley said the research focused on the Acropora tenuis and Acropora millepora species.
"We were able to get … very good fertilisation," she said.
"So that was another big win … the baby corals, they divided normally, they grew normally."
Dr Quigley said the new corals were also showing signs of greater resilience to heat.
"In terms of heat tolerance, we have already started to see a very big difference between the ones that can survive really well at high temperatures, and the ones that are a bit weaker," she said.
She said experiments in coming months would investigate the genes responsible for better performance under higher temperatures.
Potential for expansion
Dr Quigley said her team's work aimed to help future-proof the World Heritage Site against predicted bleaching events.
She said it was likely the method could be more widely applied.
"Many coral species are hermaphrodites, so we anticipate that we'd able to apply selective breeding pretty broadly across them," she said.
"That said, corals still are mysterious animals and there's some really fundamental biology we still need to understand in terms of how they reproduce and the kind of conditions that they need."
Bleaching events are expected to increase to once a year by 2046.
But Dr Quigley said strong action to counteract climate change needed to be the top priority.
"Then work to develop these kinds of conservation methods, because even if we can breed additional degrees, or additional points of degrees for corals, at some point that capacity will run out," she said.
"And we'll be in the same situation if temperatures continue to rise."
