Recent research indicates that selective breeding may slightly enhance the heat tolerance of corals.
Conducted by specialists at Newcastle University’s Coralassist Lab, the study marks the first instance of selectively breeding adult corals to boost their heat tolerance, which refers to their ability to endure severe marine heatwaves. The breeding initiative proved successful, highlighting that it is possible to enhance the heat resistance of adult coral progeny within just one generation.
Nevertheless, the increase in heat tolerance was limited, especially considering the extreme marine heatwaves anticipated due to climate change. The researchers emphasize that prompt reductions in global greenhouse gas emissions are crucial for fighting climate change and allowing corals a chance to adapt.
This research was published in Nature Communications and was conducted in collaboration with several institutions, including the University of Victoria, Horniman Museum and Gardens, Palau International Coral Reef Center, University of Derby, and the University of Exeter.
The publication is the culmination of a five-year project initiated by Dr. James Guest, funded by the European Research Council.
Not a one-size-fits-all solution
“This research demonstrates that selective breeding is a viable approach but it is not a catch-all solution, and further investigation is necessary to optimize breeding results,” states Liam Lachs, the lead author and a Postdoctoral Research Associate at Newcastle University. He adds that “at the same time, rapid global greenhouse gas emission reductions are essential to mitigate warming and provide corals with the opportunity to adapt.”
Dr. Guest, who is a Reader in Coral Reef Ecology at Newcastle University’s School of Natural and Environmental Sciences, describes the findings as showing that “selective breeding could serve as a practical method to enhance population resilience. Nonetheless, many hurdles remain. How many corals need to be outplanted to assist wild populations? Can we ensure there are no negative consequences (initial evidence suggests this is not a major risk)? How can we prevent dilution of selected traits once they are introduced into the wild? How can we maximize the beneficial selection responses?
“Considering the moderate advancements seen in this study, the effectiveness of such interventions will also greatly rely on urgent climate action.”
Successful breeding trial
Humans have practiced selective breeding for thousands of years to cultivate animals and plants with preferred traits. Nowadays, this technique is being explored as a means of conservation, particularly for coral reefs. These vital marine ecosystems are significantly affected by climate change, with reef-building corals being especially vulnerable to marine heatwaves that can lead to extensive coral bleaching and mortality, contributing to significant declines in reefs worldwide.
The team carried out selective breeding tests focusing on two traits: tolerance to a brief, intense heat exposure (10 days at +3.5°C) and a less severe but prolonged exposure typical of natural marine heatwaves (1 month at +2.5°C).
The researchers discovered that breeding from parent colonies that exhibited higher heat tolerance resulted in increased tolerance among their adult offspring. This finding applied to both the short and long exposure tests. In theory, heat tolerance could potentially be improved by around 1 °C-week within a single generation; however, this level is probably inadequate to keep up with ongoing warming trends.
What comes next?
The trials for short-stress tolerance did not show improved survival rates for offspring during long heat exposure, indicating a lack of genetic correlation. This suggests that these traits might be governed by different genetic controls, which could have significant implications for breeding strategies. Effective and quick assessments could help in identifying heat-tolerant colonies for breeding, however, if these evaluations do not predict survival rates in natural heatwave conditions, it poses a considerable challenge for management interventions.
Dr. Adriana Humanes, the study’s lead author and a Postdoctoral Research Associate at Newcastle University’s Coralassist Lab, emphasizes that: “there is substantial work ahead before selective breeding can be properly applied. We require a deeper understanding to identify which traits need prioritizing and the genetic relationships between these traits.”
Key takeaway
The authors assert that this study serves as an essential proof of concept: selectively breeding corals for their ability to survive heatwaves is indeed achievable. They urge for further research and development to determine how to implement breeding interventions effectively and maximize results, ideally keeping pace with the manageable levels of warming that can be attained through urgent climate actions.
