Coral Recruitment and Survival in a Remote Maldivian Atoll 11 Years Apart

Recruitment is a crucial process for the recovery of coral populations after large-scale disturbances causing mass mortality events such as coral bleaching. This study examined the juvenile coral community of the remote Huvadhoo Atoll (southern Maldives, Indian Ocean) 11 years apart (2009 and 2020). Coral recruits (≤5 cm) and juveniles (5–15 cm) were surveyed at eight reef sites located in both lagoon- and ocean-facing environments, under the hypothesis that density and survival of recruits differ with respect to exposure. The total mean number of recruits differed slightly between years, with densities of 25 individuals·m−2 in 2009 and 30 individuals·m−2 in 2020. However, Acropora populations, which represented 60% of juvenile corals in 2009, halved in 2020, particularly in ocean reefs. The decrease in Acropora recruits seems to have favoured other corals: Pocillopora doubled compared to 2009, and species with massive growth morphologies became dominant. In all, the juvenile coral community structure underwent substantial changes between the two surveys. The comparison between the number of recruits and that of juvenile corals suggested higher survival of the species with massive growth morphologies. Whether branching corals will also have the ability to adapt to increasingly frequent climatic disturbances deserves attention in the future.