Scientists test limits with coral breeding to boost heat tolerance, study reveals

Scientific researchers have successfully bred corals to withstand a higher heat tolerance in an effort to contribute to a future in coral conservation. Researchers at Newcastle University's Coralassist Lab have launched the world's first attempt to both selectively breed adult corals as well as improve their ability to survive heatwaves in marine atmospheres.

In a peer-reviewed study originally published in Nature Communications, researchers found that selective breeding can modestly enhance heat tolerance in coral offspring, even within a single generation. However, the improvement remains limited when compared to the severity of future marine heatwaves expected under ongoing climate change. 

The study's authors emphasized the role that greenhouse gas emissions play in threatening coral reefs.

The research, conducted over five years in collaboration with multiple institutions, including the University of Victoria and the Palau International Coral Reef Center, focused on breeding coral colonies with greater resilience to two types of heat stress: short, intense heat exposure and less intense, long-term heat exposure typical of natural marine heatwaves. The results showed that breeding parent colonies with higher heat tolerance resulted in offspring that were more resilient to both types of stress.

However, the gains were modest—improving heat tolerance by approximately 1°C-week—which, according to the researchers, may not be enough to combat the rapid pace of climate change without other serious interventions in place.

"This work shows that selective breeding is feasible, but it is not a silver bullet solution," said Liam Lachs, Postdoctoral Research Associate at Newcastle University and lead author of the study. "More research is needed to maximize breeding outcomes, but alongside this, urgent action to reduce global emissions is vital if we want to give corals a chance to adapt."

Especially in the world of scientific research, results did not come overnight and challenges will only continue in the future. While the selective breeding of corals offers hope, the scientists caution that several challenges remain before this approach can be fully implemented in the wild.

Dr. James Guest, Reader in Coral Reef Ecology at Newcastle University, highlighted key questions that need to be addressed: "How many corals need to be outplanted to benefit wild populations? Can we avoid trade-offs, and how can we ensure selected traits are not diluted once added to natural populations?"

The study found no genetic correlation between short-term and long-term heat tolerance. This revealed that corals may operate under independent genetic controls, presenting a major challenge for the future of conservation efforts.

Study co-author Dr. Adriana Humanes, a Postdoctoral Research Associate at Coralassist Lab, stressed that further research is needed to better understand which traits to prioritize and how to optimize breeding interventions. The researchers are calling for additional development to ensure these techniques can keep pace with climate change, particularly if global emissions are reduced and coral populations have the opportunity to adapt.

Despite the hurdles, the researchers view their work as an important proof of concept. "Selective breeding corals for adult heatwave survival is possible," the authors concluded. "Now, we need to focus on operationalizing breeding interventions and maximizing outcomes, while pushing for strong climate action to limit warming."

With coral reefs facing unprecedented threats from warming seas, selective breeding could become an essential tool in the fight to preserve these vital ecosystems. However, as the study underscores, it is just one part of a much larger battle to combat the impacts of climate change.

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