ABSTRACT Following catastrophic population declines in the 1980s and 2022, the keystone herbivore Diadema antillarum has become a focal species for Caribbean‐wide restoration initiatives. In the present work, we combined an 11‐month field survey across four reefs on the island of Culebra, Puerto Rico, with reciprocal transplants to evaluate physiological performance and DNA methylation responses of D. antillarum to seawater temperature, salinity, sedimentation, and nutrient gradients. Environmental parameters varied significantly across sites and seasons (GLM, p < 0.01). Urchin densities were negatively correlated with sedimentation, and righting response (a proxy for neuromuscular function) slowed under elevated sedimentation. Epigenetic analyses revealed extensive DNA methylation variation clustering by season rather than site. Righting response correlated significantly with DNA methylation patterns, suggesting a role of epigenetic regulation in physiological plasticity. Surviving transplanted urchins rapidly recovered normal righting behavior, indicating individual‐level acclimatization despite ~50% transplant mortality primarily attributed to handling stress rather than environmental incompatibility. Collectively, our results suggest that restoration efforts should prioritize low‐sedimentation sites (< 30 mg·cm −2 ·day −1 ) while implementing refined handling protocols and preconditioning strategies to enhance transplant success and minimize procedural mortality in suboptimal environments.
Lopez‐Jimenez et al. (Thu,) studied this question.