Building heat-resilient Caribbean reefs: integrating thermal thresholds and coral colonies selection in restoration

Abstract

Caribbean reefs face increasingly frequent bleaching events, compounding existing threats. Mitigation requires both global climate action and local strategies such as reef restoration. Active restoration with thermotolerant coral colonies shows promise, but context-specific thermal thresholds and standardized assessment methods remain lacking. This study addressed these gaps in two phases: (1) identifying species-specific thresholds for heat stress responses, and (2) developing a framework to prioritize resilient colonies. In phase one, 70 colonies from seven species in southeastern Dominican Republic reefs were tested using 3-hour heat pulse assays above the local maximum monthly mean (MMM), combining bleaching ranks, pixel intensity, and PAM fluorometry to determine T50 thresholds. In phase two, 99 colonies from five species were repeatedly tested at MMM and T50 to assign thermal performance scores. By integrating inter- and intraspecific thermotolerance, this study proposes a practical framework to guide coral restoration under climate change.