Coral thermotolerance retained following year-long exposure to a novel environment

Active restoration strategies targeting corals with elevated heat tolerance have the potential to enhance reef resistance under a warming climate. While stress-tolerant corals have been documented in extreme systems such as mangrove lagoons, it is critical to assess the ability of these corals to maintain tolerance when moved to a more benign habitat. Here, we translocated corals from a mangrove lagoon to an adjacent reef and evaluated the thermal thresholds of corals from both locations before translocation and after 1 year. We demonstrate that mangrove colonies have higher thermal tolerance than reef corals, and, critically, mangrove colonies exhibited no loss in thermal tolerance following 1-year translocation to a less extreme reef habitat. Up-regulation of genes associated with DNA repair, metabolism, and homeostasis indicates the importance of these pathways in helping mangrove corals mitigate thermal stress. Our findings suggest the use of heat tolerant corals from extreme systems holds promise as part of intervention strategies aiming to increase reef resistance.