Reef connectivity: Genetic analysis of recruitment and gene flow among Caribbean scleractinian corals

Larval recruitment, the settlement and survival of larvae, is a primary factor in determining the species composition of a marine community, maintaining population sizes within the community and influencing the genetic structure of species across their geographic distribution. In addition, patterns of connectivity between marine populations, which are mediated by larval dispersal and recruitment, are crucial in understanding the ability of a population to recover after a perturbation. To aid in the understanding of larval dispersal and recruitment patterns, genetic techniques were utilized to identify recently settled scleractinian coral recruits and to evaluate the genetic structure of adult and juvenile populations of Montastraea cavernosa within and among reefs of the Florida Keys, Bermuda, the Bahamas and the Flower Garden Banks. Recruitment throughout the Florida Keys and the Flower Garden Banks varied spatially and temporally, and was dominated by the brooding species, Agaricia agaricites and Porites astreoides. Analysis of the population genetic structure of M. cavernosa adults revealed genetic homogeneity across adult populations at moderate scales, however this species is not comprised of a single panmictic population over its distribution. It appears that the initial supply of larvae is generally homogenized as indicated by the similarity of juvenile populations within and between most geographic locations. These patterns of genetic structure suggest that dispersal of M. cavernosa larvae is widespread, however other factors act to differentiate adult populations. Despite the general genetic homogeneity of adults within a geographic location, comparisons among adult (potential source) and juvenile populations detected temporal variation in gene flow indicating that different populations may contribute differentially to the larval pool over time. Incorporation of genetic assessments into marine resource management plans should be considered in order to design functionally effective marine reserves.