UC San Diego

Mechanisms of change in coral colonies are necessary components to accurately predict trajectories of coral reef health. Yet, little in-field data has been quantified regarding the demographic rates of change in colonies and the factors that influence them. In this study, we use a large-area imaging approach to estimate baseline demographic rates of the coral genus Pocillopora and test for the influence of colony-specific predictors on growth, shrinkage (i.e. colony survivorship with loss of live tissue), and mortality (i.e. whole colony loss). We found that a colony’s fate was linked to its initial size, with larger colonies experiencing far lower mortality rates but higher shrinkage rates than smaller colonies. In addition, historical effects also significantly affected colony fate, as colonies with recent history of shrinkage experienced further shrinkage and mortality the following year. Finally, we found that significant variability in growth and mortality rates were linked to in inter-island site differences, which we suspect is driven by differences in heterotrophic feeding rates.