Marine heatwaves driven by climate change are pushing coral reefs to the brink, with recent global bleaching events affecting over 84% of the world's reefs since 2023. In this dire context, a groundbreaking study from Newcastle University's Coralassist Lab offers hope through assisted evolution. Researchers have demonstrated that carefully selecting specific coral traits can significantly boost heat tolerance, potentially enabling corals to withstand future ocean warming.
The study, published in Current Biology, tracked a pedigree coral population over eight years in Palau, revealing heritable traits that enhance survival without compromising growth or reproduction.Read the full paper here.
The Newcastle University Coralassist Lab: Pioneering Resilience Research
Newcastle University's Coralassist Lab, led by Dr. James Guest, specializes in multi-disciplinary approaches to coral conservation. Their work combines physiology, genetics, and modeling to address Anthropocene challenges. This latest research builds on years of field experiments in Palau, where the team developed the first pedigree-tracked adult coral population for quantitative genetics analysis.
Dr. Liam Lachs, former postdoc at Newcastle and now at the University of Queensland, and Dr. Adriana Humanes co-led the study. By mapping family relationships and measuring trait inheritance, they quantified genetic merit for heat tolerance—a step change in understanding how to implement assisted evolution effectively.
Understanding Assisted Evolution in Corals
Assisted evolution accelerates natural adaptation via human intervention, akin to selective breeding in agriculture. For corals, it involves choosing parent colonies with superior heat tolerance to produce more resilient offspring. Unlike wild populations, where larvae disperse widely, captive breeding allows precise genetic tracking.
The process: Collect fragments from diverse colonies, expose to controlled heat stress (e.g., 32.5°C for one month simulating marine heatwaves), measure survival, and select top performers as broodstock. Repeat over generations to amplify tolerance.
Key Coral Traits Driving Heat Tolerance
The study identified several heritable traits linked to heat survival:
- Survival under prolonged heatwaves: Direct measure of endurance at elevated temperatures.
- Acute heat tolerance: Resistance to short, intense spikes.
- Growth rate: Faster-growing corals recover better post-stress.
- Reproduction: Spawning success ensures population continuity.
- Calcification: Skeleton building for structural integrity.
- Tissue biomass: Energy reserves for stress response.
- Symbiont flexibility: Ability to shuffle heat-resistant algae partners.
Crucially, no negative genetic correlations existed—improving one trait didn't harm others, a boon for breeding programs.
Genetic Correlations and Selection Intensity
Using advanced statistical models, researchers found weak-to-moderate positive correlations between prolonged heatwave tolerance and acute exposures. However, correlations weaken at hotter temperatures, stressing the need for trait-specific selection.
To match projected warming, select the top 1-5% most tolerant corals repeatedly. Simulations predict meaningful gains in persistence, but demand large-scale testing (e.g., 1,000 corals to breed from 50).
Newcastle press release details the methodology.
Photo by David Diehm on Unsplash
Challenges in Scaling Assisted Evolution
While promising, hurdles remain: Maintaining genetic diversity to avoid inbreeding, logistical costs of ocean nurseries, and ethical concerns over genetic modification. The lab emphasizes assisted evolution complements—not replaces—emissions reductions.
Dr. Guest notes: “Producing corals from parental colonies with known histories has advanced our understanding of effective implementation.”
Palau: Real-World Testing Ground
Palau's reefs, stressed yet resilient, host the lab's ocean nursery. Here, one-year-old corals undergo heat challenges mimicking future scenarios. Results inform local restoration, with outplanting super-corals to bolster wild populations.
UK's Broader Commitment to Coral Research
Newcastle's work aligns with UK initiatives like the £3.7 million NERC-funded mesophotic coral project involving Plymouth University, Imperial College London, and Plymouth Marine Laboratory. This assesses deep reefs' resilience to warming.
Exeter University's modeling predicts Indo-Pacific reefs ceasing growth by 2040 under moderate warming. UKRI and Blue Planet Fund (£500m) support global efforts, positioning UK universities as leaders.
Global Coral Crisis: Stark Statistics
The fourth global bleaching event (2023-2025) hit 84% of reefs across 83 countries, surpassing prior records. At 1.5°C warming, 70-90% loss projected by 2050; 99% at 2°C. UK overseas territories like Pitcairn face similar threats.
Marine heatwaves, now 5x more frequent, cause mass mortality. Assisted evolution offers localized hope amid urgency for net-zero transitions.
Implications for Policy and Reef Management
Findings urge prioritizing heat-tolerant strains in restoration. UK policy could fund scaling via NERC, while international platforms like CORDAP accelerate global trials. Stakeholders: governments, NGOs, fisheries.
Photo by Kiros Amin on Unsplash
Career Opportunities in UK Marine Research
Newcastle and peers seek experts in genetics, ecology. Roles span postdocs to faculty, vital for advancing solutions. UK universities drive innovation, blending lab/field work with impact.
Future Outlook: Hope Through Science
With strategic trait selection, corals may persist. Newcastle's blueprint guides global efforts, underscoring universities' role. Yet, ultimate survival hinges on curbing warming—research informs action.
