Phenotypic variation in two widespread Caribbean corals — Porites astreoides and P. divaricata — between mangrove and lagoon habitats

As coral reefs experience dramatic declines in coral cover throughout the tropics, there is an urgent need to understand the role that non-reef habitats such as mangroves play in the ecological niche of corals. Mangrove habitats present a challenge to reef-dwelling corals as they can differ dramatically from adjacent reef habitats with respect to key environmental parameters such as temperature and light. As variation in temperature and light within reef habitats is known to drive intraspecific differences in coral phenotype, we hypothesized that coral species which can exploit both reef and mangrove habitats will exhibit predictable differences in phenotype between habitats. To investigate how intraspecific variation, driven by either local adaptation or phenotypic plasticity, might enable particular coral species to exploit these two qualitatively different habitat types, we compared the phenotypes of two widespread Caribbean corals — and in mangrove versus lagoon habitats on Turneffe Atoll, Belize. We document significant differences in colony size, color, structural complexity, and corallite morphology between habitats. In every instance, the difference between mangrove and lagoon corals was consistent in and . This study is the first to document intraspecific phenotypic diversity in corals occupying mangrove versus patch-reef habitats, and it provides a foundation for understanding why some “reef coral” species can exploit mangroves, while others cannot.