Reviewed by Lexie CornerOct 15 2024
A study published in Nature Communications highlights the world’s first attempt to selectively breed adult corals for enhanced heat tolerance, led by specialists at Newcastle University’s Coralassist Lab.
The findings show that coral heat tolerance can be slightly improved through selective breeding, and this increase was observed within a single generation of adult coral offspring.
However, the improvement was modest when compared to the future marine heatwaves predicted under climate change. The authors emphasize that rapid global reductions in greenhouse gas emissions are essential to mitigate warming and allow corals to adapt to rising temperatures.
The research was conducted in collaboration with the University of Victoria, Horniman Museum and Gardens, Palau International Coral Reef Center, University of Derby, and University of Exeter. The study is the result of a five-year project initiated by Dr. James Guest and funded by the European Research Council.
Not a Silver Bullet Solution
This work shows that selective breeding is feasible but not a silver bullet solution and that more research is needed to maximize breeding outcomes.
Liam Lachs, Study Lead Author and Postdoctoral Research Associate, Newcastle University
He says that “in parallel, rapid reductions of global greenhouse gas emissions are an absolute requirement to mitigate warming and give corals an opportunity to adapt.”
Dr. Guest, Reader in Coral Reef Ecology at Newcastle University’s School of Natural and Environmental Sciences, added that “the results show that selective breeding could be a viable tool to improve population resilience. Yet, there are still many challenges that need to be overcome. How many corals need to outplanted to benefit wild populations? Can we ensure there are no trade-offs (evidence so far suggests this is not a large risk)? How can we avoid dilution of selected traits once added to the wild? How can we maximize responses to selection?”
He added, “Given the moderate levels of enhancement we achieved in this study, the effectiveness of such interventions will also depend on urgent climate action.”
Successful Breeding Trial
For thousands of years, selective breeding has been used to cultivate plants and animals with desirable traits. Now, this approach is being explored as a tool to protect nature, particularly coral reefs. Reef-building corals are highly vulnerable to marine heatwaves, which are becoming more frequent due to climate change. These heatwaves cause widespread reef decline, coral bleaching, and mass mortality.
In this study, researchers conducted selective breeding trials targeting two traits: tolerance to short, intense heat exposure (10 days, up to +3.5 °C) and a longer, less intense exposure typical of natural marine heatwaves (1 month, up to +2.5 °C). They found that breeding parent corals with higher heat tolerance produced offspring with enhanced heat tolerance for both exposure scenarios.
Theoretically, heat tolerance could increase by approximately 1 °C per generation, but this improvement may not be sufficient to keep pace with the rapid warming expected if climate change continues unchecked.
What’s Next?
There was no evidence that selectively breeding for short-term heat stress tolerance enhanced the offspring's ability to endure prolonged heat exposure. This suggests that these traits may be governed by different genetic mechanisms, as no genetic correlation has been found between them.
This finding has important implications. Quick and cost-effective assays to identify heat-tolerant colonies for breeding would be valuable for conservation efforts. However, if these tests fail to predict adult colony survival during natural marine heatwaves, it presents a significant challenge for management interventions.
Considerable work remains before selective breeding can be successfully implemented. A deeper understanding is needed to determine which traits to prioritize and how these traits are genetically correlated.
Dr. Adriana Humanes, Study Lead Author and Postdoctoral Research Associate, Coralassist Lab, Newcastle University
Take Home Message
The authors highlight that this study is a crucial proof of concept, demonstrating the feasibility of selectively breeding corals for adult heatwave survival. They emphasize the need for further research and development to refine and operationalize these breeding interventions, with the goal of maximizing outcomes and potentially keeping pace with the lower levels of warming that could be achieved through simultaneous climate action.
Journal Reference:
Humanes, A. et. al. (2024) Selective breeding enhances coral heat tolerance to marine heatwaves. Nature Communications. doi.org/10.1038/s41467-024-52895-1