Sex-related differences in the sclerochronology of the reef-building coral Montastraea cavernosa : the effect of the growth strategy

To investigate sex-related differences in the skeleton of the reef-building coral Montastraea cavernosa, a gonochoric broadcaster species with an annual cycle of gametogenesis, we collected six colonies during the reproductive season. Sex was determined by histological techniques and sclerochronological characteristics of digital X-ray images. Our results show, as previously reported for other gonochoric corals, differences in the sclerochronological characteristics between female and male colonies. Tissue thickness, density and calcification rate are significantly lower in females than in males, whereas there is no difference in extension rate between sexes. These are the first complete sclerochronological results reported for M. cavernosa, and for gonochoric species with solid skeletons. We conclude that sex differences in this coral arise by coupling energetic costs of reproduction and the growth strategy, and argue that it is important to consider how sclerochronological characteristics vary between sexes of gonochoric species when interpreting climate and environmental proxies from coral skeletons.