Scientists have taken a significant step toward protecting coral reefs by successfully breeding corals with improved heat tolerance, according to a new study.
This groundbreaking research, led by Newcastle University’s Coralassist Lab, marks the world’s first attempt at selectively breeding adult corals to withstand increasingly frequent marine heatwaves.
While the results show promise, the modest improvement in heat tolerance highlights the urgent need for drastic global action on climate change to ensure the survival of coral reefs.
“This work shows that selective breeding is feasible but not a silver bullet solution and that more research is needed to maximize breeding outcomes,” says study lead author Liam Lachs. He continues, reflecting that “in parallel, rapid reductions of global greenhouse gas emissions are an absolute requirement to mitigate warming and give corals an opportunity to adapt.”
Improving coral heat resistance
Selective breeding has long been used to enhance desirable traits in plants and animals, but this study explores its potential for nature conservation—specifically coral reefs, which are extremely vulnerable to the effects of climate change.
Marine heatwaves have already triggered widespread coral bleaching and mortality, leading to significant declines in reefs worldwide. The researchers hoped that breeding corals with better heat tolerance could help these vital ecosystems adapt to warming oceans.
Dr. James Guest, a Reader in Coral Reef Ecology at Newcastle University, echoed Lachs’ caution, noting that selective breeding could be a valuable tool to enhance coral populations’ resilience but that many challenges remain. “Given the moderate levels of enhancement we achieved in this study the effectiveness of such interventions will also depend on urgent climate action,” he said.
Guest also highlighted several hurdles, such as determining how many selectively bred corals would need to be introduced to wild populations to make a significant impact and ensuring that desirable traits aren’t diluted when added to the wild.
Selective breeding not enough?
The study focused on two breeding trials to improve tolerance to both short-term and long-term heat exposure. One test involved exposing corals to an intense 10-day heatwave, with temperatures rising by 3.5°C, while the other simulated a less intense but longer, one-month heatwave with temperatures increasing by 2.5°C—conditions that mirror natural marine heatwaves.
In both trials, the offspring of corals bred for high heat tolerance outperformed those from less heat-tolerant parent colonies, showing that selective breeding can improve heat tolerance even in just one generation. The improvement equated to about a 1°C increase in tolerance over one week, a valuable gain, but one that is likely insufficient to keep pace with the projected rise in ocean temperatures if climate change continues unabated.
Importantly, the study revealed that selective breeding for short-term heat tolerance did not necessarily confer long-term heat resilience, suggesting that these traits may be controlled by different genetic factors.
This discovery raises concerns for future management strategies. While quick, cost-effective methods for identifying heat-tolerant coral colonies are essential, it’s crucial that these methods accurately predict survival during real-world marine heatwaves . Otherwise, efforts to enhance coral resilience through selective breeding may fall short.
Not a ‘silver-bullet solution’
Despite these complexities, the research is seen as an important proof of concept, demonstrating that breeding corals to better withstand heat stress is possible. The study’s authors, as mentioned in the press release , are calling for more research to refine selective breeding techniques and ensure they are as effective as possible.
The hope is that, with simultaneous efforts to curb global warming, selective breeding could help corals survive the more moderate warming scenarios that may be achievable with concerted climate action.
In conclusion, while this study offers a glimpse of a potential tool for coral conservation, it underscores the broader need for urgent climate action. Without rapid reductions in global emissions, the modest gains from selective breeding may not be enough to safeguard coral reefs from the worsening impacts of climate change.
The study has been published in Nature Communications .
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