Caribbean mangrove forests act as coral refugia by reducing light stress and increasing coral richness

Abstract

Caribbean mangrove forests act as coral refugia by reducing light stress and increasing coral richness.

Novel coexisting mangrove-coral habitats: Extensive coral communities located deep within mangrove canopies of Panama, a global classification system and predicted distributions

“…The prevalence of plating and encrusting coral growth forms within the mangrove canopy as well as the color variation between coral colonies, suggest plasticity in growth form and photophysiology in response to the complexity of mangrove architecture where average light does not decrease with distance into the canopy and instead is patchy due to variation in canopy structure (e.g., sunflecks) and forest density. Since coral distribution within mangroves can be patchy [ 38 , 44 , 46 ], we suggest that coral distribution may be more closely related to light than temperature limitations. Darker pigment and flattened morphologies of corals are common in mesophotic reefs [ 70 – 72 ] as a physiological adaptation to low light conditions.…”

“…These adaptations maximize light captured by increasing light-harvesting pigments and reducing the ratio of tissue to projected area for increased light capture efficiency [ 73 – 75 ], and could be utilized within the mangrove for the same purpose. Further, flattened morphologies may be a response of coral colonies to grow through lateral expansion rather than upward to avoid exposure at low tide [ 44 ]. However, the thin plate and cup forms of coral colonies may also limit growth within the mangrove habitat as these corals are extremely fragile and have been observed to break with root movement (e.g., swaying from boat wake).…”

“…Mangrove forests serve as critical habitat for many coral species [ 36 , 38 , 44 ], but can also be an extreme habitat, with low pH and highly variable temperature range, that selects for stress tolerant corals [ 20 , 46 – 48 , 76 , 77 ]. Further research is needed to identify whether the roles served by mangroves are also reflected in CMC types, and if these are geographically distinct.…”

“…All presently reported CMC habitats in the literature occur at a shallow depth and are microtidal (≤2 m) [ 36 , 44 , 47 , 48 , 61 , 62 ]. We therefore narrowed down the potential CMC habitat by areas with a tidal amplitude of ≤2 m, since a greater tidal amplitude would lead to prolonged air exposure of corals in this area.…”

Neither Coral- nor Symbiont- Genetic Diversity may Explain the Resistance of the Coral <i>Echinopora lamellosa</i> to Bleaching

“…High survivability of corals are often found within or close to coastal vegetation, such as mangrove forest or vast seagrass bed (Camp et al 2016;Lord et al 2020). Mangrove vegetation not only exports litter to its adjacent ecosystems but also disperse dissolved tannin (López-Portillo et al 2017;Stewart et al 2021). The dissolved tannin and other chromophoric dissolved organic matter (CDOM) derived from marine plants may protect corals under the stress of water temperature from excessive ultraviolet radiation (UV-R) exposure and act as a pH buffer during the bleaching (Kellogg et al 2020).…”