Coral recruitment in the Florida Keys: Patterns, processes, and applications to reef restoration

Coral recruitment is an essential process that influences community structure and can determine a reef\u27s resiliency and ability to recover from decline. Understanding coral recruitment is particularly important in the face of continuing decline of the world\u27s coral reefs from a variety of both natural and anthropogenic stresses. The goal of this study was to examine coral recruitment in the Florida Keys and to investigate some factors that may influence patterns of coral community structure observed on the reefs. Nine patch reefs from the upper to the lower Florida Keys were surveyed for differences in juvenile coral distribution. In addition, coral recruitment, growth and mortality rates in the upper Keys were measured and utilized to construct a model of juvenile coral population dynamics. Both lower densities and dissimilar taxonomic distribution of recruits were found in the upper Keys region versus the middle and lower Keys. The presence of macroalgae and crustose coralline algae and the availability of topographically complex habitat, all of which have the potential to affect coral recruitment, did not correlate with observed juvenile coral distribution patterns. The only factor examined that correlated with juvenile coral abundance was the presence of adult colonies. The density of Siderastrea spp. recruits increased with increasing benthic cover of Siderastrea spp. Similarly, density and surface area of adult Porites astreoides colonies were positively correlated with juvenile density. Differences in coral community structure could not be attributed to differences in recruitment, growth, or mortality. However, the occurrence of partial mortality varied between sites and years and may be a process that produces reduced coral cover and smaller size class distributions over time. Lastly, coral recruitment to reef restoration sites designed to enhance and speed recovery from vessel groundings was assessed to determine the efficacy of these restoration projects. While all the methods employed were deemed successful based on the equal or increased density and taxonomic richness of recruits compared to reference sites, some techniques attracted higher densities of recruits. Both the material used in the restoration and the orientation of the restoration material were factors that contributed to the effectiveness of the restoration efforts