As climate change continues to warm the oceans, coral reefs across the world are facing an increasingly uncertain future. Rising sea temperatures are fueling stronger and more frequent marine heatwaves, events that often trigger coral bleaching and large-scale mortality. A new study led by Newcastle University suggests that helping corals survive these future heat extremes will depend on strong and strategic trait selection over multiple generations.
A New Hope for Coral Reefs
The research explores the potential of assisted evolution, a scientific approach that accelerates the natural adaptation process. Instead of waiting for corals to slowly evolve on their own, scientists are identifying and breeding individuals with the most desirable traits, especially those linked to heat tolerance.
To investigate this, researchers spent eight years developing a unique pedigree-tracked coral population. This allowed them to study how important traits such as survival, growth, and reproduction are passed from one generation to the next. Using advanced statistical models, the team identified which coral lineages carry the strongest genetic potential to withstand prolonged heatwaves.
Survival Depends on the Right Traits
The study found that simply selecting corals that survive short bursts of heat is not enough. Instead, breeding efforts must focus directly on long-term heatwave survival, which is more closely linked to future ocean conditions.
To keep pace with rapid global warming, scientists estimate that only the top 1–5% most heat-tolerant corals should be selected as breeding stock. Moreover, this intense selection process would need to be repeated across several generations to produce meaningful gains in resilience.
Encouragingly, the researchers found no evidence that improving heat tolerance negatively affects other vital traits like growth or reproduction. This means stronger corals may still remain healthy and capable of sustaining reef ecosystems.
Not a Complete Solution
However, the team stresses that assisted evolution is not a standalone fix. While selective breeding may buy reefs valuable time, cutting greenhouse gas emissions remains essential. Without global climate action, even the most heat-tolerant corals may struggle to survive in the decades ahead.
