Differences in bleaching susceptibility and mortality are apparent among coral species, and have been variously ascribed to differences in physiology and morphology, in particular overall growth form (e.g., branching versus massive corals). However, coral morphology is highly confounded with taxonomy, and no studies have tested for differences in bleaching susceptibility among corals with varying morphology within (rather than between) coral families. For this study, data were compiled for bleaching susceptibility and mortality from 65 published studies that monitored coral health throughout the bleaching event. Overall patterns of bleaching susceptibility were significantly different among coral growth forms, whereby a much higher proportion of branching, tabular, and submassive corals bleached compared to encrusting, massive, and free-living corals. However, differences in bleaching susceptibility and mortality were not consistent among growth forms within families. Branching faviid species (e.g., Echinopora) had much lower incidence of bleaching compared to massive species, but the reverse was true for Acroporidae and Poritidae. Moreover, mortality was markedly different amongst growth forms within families, such that massive Acroporidae (e.g. Montipora) suffered highest mortality when compared to Faviidae and Poritidae, but branching Acroporidae suffered lowest mortality compared to branching Faviidae and Poritidae. Our data suggest that generalities about the susceptibility of branching versus massive corals (and among other major growth forms) arise at least in part because certain growth forms are over-represented by highly susceptible coral taxa (e.g., Acropora) or perhaps because branching corals generally maintain higher dominance than massive corals
