As marine ecosystems reel from the impact of rising ocean temperatures, international researchers have achieved a breakthrough: corals with boosted heat tolerance, bred for survival in a warming world.
Using the World Heritage-listed Ningaloo Reef—Australia’s largest fringing coral reef spanning 300 kilometres off the country’s north-west coast—as their research base, the team found that selectively bred coral offspring with at least one parent from warmer reefs had double the survival rate under extreme heat stress compared to those from cooler areas.
“This marks the first successful demonstration of how selectively breeding Indian Ocean corals can boost heat tolerance and signals a crucial tool to aid reef survival in the short term,” says Dr Andrew Forrest, a philanthropist and mining billionaire who financed the study. “Of course, the only real and lasting solution to ending the destruction of coral reefs is the complete phase out of fossil fuels.”
But in the meantime, could coral resilience be engineered—one generation at a time?
The study assessed the heat tolerance of two widespread reef-building Acropora species at Ningaloo. Researchers compared corals from two distinct locations along the reef: a warmer northern site and a cooler southern site.
“We wanted to see if the small temperature differences between these two relatively close locations had resulted in corals with enhanced heat tolerances,” says Dr Kate Quigley, a molecular ecologist and Principal Research Scientist at Minderoo Foundation. “Coral babies with at least one parent from the warmer reef exhibited significantly higher survival rates under heat stress.”
They found that coral larvae with one parent from the warmer population doubled their ability to survive at very high temperatures of 35.5°C, compared to larvae bred only from parental corals from the cooler population.
“This is the first study to demonstrate that selective breeding can effectively enhance heat tolerance in corals within the Indian Ocean, effectively doubling their heat tolerance with this method in one critical species,” says Quigley. “These findings are crucial for developing strategies to protect coral reefs as marine heatwaves become more frequent and intense. It could provide us with time as we transition away from the use of fossil fuels, which are driving these extreme climate impacts.”
The discovery lands in the shadow of a troubling milestone. In March 2025, both of Australia’s World Heritage-listed reefs—Ningaloo and the Great Barrier Reef—bleached in unison for the first time on record. It’s a stark indicator of the growing reach of marine heatwaves.
As greenhouse gases accumulate in the atmosphere, they trap more of the sun’s energy, and over 90% of that excess heat is absorbed by the ocean. This steady build-up of heat is driving long-term increases in sea surface temperatures.
Since 1900, sea temperatures around Australia have risen by 1.08 °C, with nine of the ten hottest years on record occurring since 2010. Ocean heatwaves—when temperatures remain at abnormally high levels for five days or more—are growing longer, more intense, and increasingly common. Unlike land heatwaves, they can persist for months or even years.
Mass coral bleaching, the primary consequence of these events, has now affected reefs in at least 83 countries, with the world currently in the midst of the fourth Global Bleaching Event, according to the NOAA Coral Reef Watch.
“Coral reefs support the livelihoods of millions of people globally, provide critical shoreline protection and support more than a quarter of the ocean’s biodiversity, but have suffered steep declines globally,” says Forrest.
“The world must arrest warming ocean temperatures urgently or face the very real prospect of the death of a majority of coral reefs globally within 50 years.”
These results are being shared at the Third United Nations Ocean Conference, currently underway in Nice, France—where global leaders, scientists, and policymakers have gathered to tackle the escalating threats facing our oceans.
What are heat tolerant corals?
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The Ultramarine project – focussing on research and innovation in our marine environments – is supported by Minderoo Foundation.