In the fight to protect coral reefs from climate change, scientists have attempted a world-first approach. They were able to successfully breed adult corals to tolerate marine heat waves.
The research was led by Newcastle University’s Coralassist Lab. Although the results showed promise, the improvement in heat tolerance was modest compared to the marine heat waves that are expected in the future.
The study emphasizes the urgent need to take drastic action, such as significantly reducing global greenhouse gas emissions, to mitigate the effects of climate change and give coral reefs a chance to adapt.
“This work shows that selective breeding is feasible but not a silver bullet solution and that more research is needed to maximize breeding outcomes,” said Liam Lachs, the lead author of the study and a postdoctoral research associate at Newcastle University in the United Kingdom.
For thousands of years, humans have practiced selective breeding to enhance desirable traits in plants and animals. But now, its potential for nature conservation is being considered, particularly for coral reefs.
Coral reefs are incredibly vulnerable to the impacts of climate change. They are highly sensitive to marine heat waves, which have already triggered widespread coral bleaching and mortality events that have led to significant declines in reefs globally.
The scientists conducted two selective breeding trials to improve the tolerance of reefs. One of the tests involved exposing corals to an intense heat wave lasting 10 days, with temperatures reaching 38.3 degrees Fahrenheit.
The other test simulated a less intense but longer heat wave lasting one month, which aligns with the conditions of natural marine heat waves. The temperatures reached 36.5 degrees Fahrenheit.
The research team found that the offspring of corals bred for high heat tolerance fared better than those bred for low heat tolerance, showing that selective breeding can enhance heat tolerance by approximately 33.8 degrees Fahrenheit per week within just one generation.
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However, the improvement is likely insufficient to combat the projected rise in ocean temperatures. The study also revealed that selective breeding for short-term heat tolerance did not show evidence of offspring being able to survive long-term heat exposure, suggesting that different genetic factors control these traits.
This has important implications for future management strategies. It would be beneficial to have quick and cheap methods for identifying heat-tolerant coral colonies for breeding.
But these methods must also accurately predict their survival during natural marine heat waves or else efforts to boost coral resilience will fail.
Further research is required to refine selective breeding techniques and to determine which traits should be prioritized.
Even though more work still needs to be done, the study is valuable proof that it is possible to selectively breed corals for heat wave survival.
The study has been published in Nature Communications.