Visual discernment of sexual recruits is not feasible for Acropora palmata

In fragmenting corals, estimation of population structure, extinction risk, and recovery potential requires accurate assessment of the relative contribution of sexual versus asexual reproduction. This yields an operational tendency for field ecologists to surmise levels of sexual recruitment from visual surveys, as in a recent study by Grober-Dunsmore et al. (2006; Mar Ecol Prog Ser 321:123-132). The recent development of microsatellite markers for threatened elkhorn coral Acropora palmata allowed us to test the accuracy of such visual assessments in 2 separate populations, showing them to be highly unreliable. Therefore, for clonal species that rely heavily on fragmentation, extreme caution is required in determining levels of sexual recruitment or recovery potential in the absence of molecular genetic screening.