Reductions in calcification in reef-building corals occur when thermal conditions are suboptimal, but it is unclear how they vary between genera in response to the same thermal stress event. Using densitometry techniques, we investigate reductions in the calcification rate of massive Porites spp. from the Great Barrier Reef (GBR), and P. astreoides, Montastraea faveolata, and M. franksi from the Mesoamerican Barrier Reef (MBR), and correlate them to thermal stress associated with ocean warming. Results show that Porites spp. are more sensitive to increasing temperature than Montastraea, with calcification rates decreasing by 0.40 g cm⁻² year⁻¹ in Porites spp. and 0.12 g cm⁻² year⁻¹ in Montastraea spp. for each 1°C increase. Under similar warming trends, the predicted calcification rates at 2100 are close to zero in Porites spp. and reduced by 40% in Montastraea spp. However, these predictions do not account for ocean acidification. Although yearly mean aragonite saturation (Ω_ar) at MBR sites has recently decreased, only P. astreoides at Chinchorro showed a reduction in calcification. In corals at the other sites calcification did not change, indicating there was no widespread effect of Ω_ar changes on coral calcification rate in the MBR. Even in the absence of ocean acidification, differential reductions in calcification between Porites spp. and Montastraea spp. associated with warming might be expected to have significant ecological repercussions. For instance, Porites spp. invest increased calcification in extension, and under warming scenarios it may reduce their ability to compete for space. As a consequence, shifts in taxonomic composition would be expected in Indo-Pacific reefs with uncertain repercussions for biodiversity. By contrast, Montastraea spp. use their increased calcification resources to construct denser skeletons. Reductions in calcification would therefore make them more susceptible to both physical and biological breakdown, seriously affecting ecosystem function in Atlantic reefs.

Ten reefs of the Veracruz Reef System (VRS) were surveyed to evaluate the distribution and prevalence of diseases that affect stony corals. Total disease prevalence on corals in the VRS was 4.8%. Seven diseases affecting 6 coral genera (4 of which are the most abundant) were observed in 85.2% of the evaluated sites. As observed in other reefs of the Caribbean, dark spots disease had the highest prevalence (2.9%) and widest distribution. The incidence of disease showed a patchy distribution, with prevalence being significantly higher on the reef flats than on the windward and leeward sides.

The discovery of alternating growth bands in the skeletons of massive corals led to the possibility of using them as environmental indicators. However, skeleton formation is the result of the growth of thousands of polyps depositing millimeter‐sized CaCO₃structures, called corallites. Nevertheless, the orientation of the corallite trajectories and their position with respect to the colony could be altering the information obtained from the skeleton. In this sense, to obtain reliable information from coral skeletons, it is necessary to understand how polyp population growth influences coral growth rates. For this reason, we present a study that combines computed tomography image segmentation, optical densitometry, and demographic equations to follow the trajectory of corallites in order to model coral growth from the replication of its corallites and understand the responses in terms of their growth. We observed that both corallite replication and skeletal growth characteristics vary significantly according to the position they occupy within the colony. The central zone of the colony promotes corallite replication, and it is in this zone that we measured the highest values of extension and calcification. These variations in vegetative and skeletal growth are possibly in accordance with the variability of available resources and environmental stimuli in different zones of the skeleton. This approach will allow us to explore future lines of research associated with the size limits of different coral species and to observe how different drivers modulate polyp budding.