Fate tracking of Acropora cervicornis colonies post-outplanting reveals genotype-specific responses to marine heatwaves

Caribbean coral reefs have suffered severe declines over the last several decades, leading to local extirpation and functional extinction of the critically endangered species, Acropora cervicornis. In response, coral restoration has become central to conservation efforts, yet genotype-specific stress resilience remains poorly integrated into restoration design, limiting overall success. Here, we evaluated thermal performance among A. cervicornis genotypes from a coral nursery at Little Cayman Island and subsequently monitored their physiological responses in the field during a 16-month common garden outplanting experiment that spanned the 2023 marine heatwave. Thermal performance curves (TPCs) generated under controlled conditions revealed visually distinct profiles among genotypes, but modeled thermal parameters did not differ significantly, suggesting broadly similar thermal ranges. In contrast, field-based physiological and survival data revealed significant genotype-specific differences in bleaching susceptibility, disease prevalence, and mortality. One genotype (OB) exhibited the highest thermal resistance, maintaining photosynthetic efficiency despite substantial endosymbiont loss, but also showed elevated disease susceptibility, suggesting a trade-off between tolerance traits. These results indicate that laboratory-derived TPCs may underestimate ecologically relevant variation in stress tolerance and highlight the need to maintain diverse genotypes in restoration programs. However, the limited genetic diversity within the A. cervicornis population at Little Cayman Island likely constrains its adaptive potential, leaving the future of both restoration success and species persistence in this region uncertain.