Abstract Summary
Coral reefs are being severely damaged worldwide. Coral restoration has been implemented to ameliorate such degradation and increase coral cover. In the last decade restoration of branching corals have been widely implemented and popularized that even non-expert citizens do it globally. Yet there are still scientific gaps that may accelerate the restoration process and increase the probability of success in the long-term. We tested whether coral populations are locally adapted, so that when transplanted to different habitats incur in increased mortality rates. We found that in the ESA threated Orbicella species, populations are adapted across depths and an increased in depth of just 5 meters sparks an increased mortality of 25% for O. annularis. O. franksi when transplanted shallower (3 m) does however remarkably well with no-mortality. We also found that the robustness of O. franksi in shallow environments is related to a faster photo-physiological adjustment to brighter environments. On the contrary, O. annularis in deep areas reaches extremely low excitation pressures that compromise algal photosynthesis and the coral-algal symbiosis. Our compilation of studies using reciprocal transplants suggests adaptation in reef anthozoans is a common phenomenon. Even under similar survivorship rates, the physiological compensation of being in a new foreign habitat decreases coral performance. Our results highlight the need to match donor and transplanted sites to increase coral yield during coral restoration. In slow growing species (< 3 cm/yr) such in Orbicella incorporating habitat information to increase the likelihood of restoration success is of greatest importance as measuring the effects of restoration may take as long as couple of decades.
