Meeting Abstract
Global change is threatening coral reefs, with rising temperature leading to repeat bleaching events (dysbiosis of the coral host and its symbiotic algae Symbiodiniaceae) and increasing pCO2 causing reductions in calcification. Global bleaching events are revealing fine-scale patterns of coral survival; however, the physiological phenotypes that lead to success under stress remain elusive. Here, we conducted a 90-day experiment to investigate the physiological responses of two Caribbean reef-building coral species (Siderastrea siderea and Pseudodiploria strigosa) from nearshore and forereef locations on the Belize Mesoamerican Barrier Reef System under ocean warming (28, 31°C) and acidification (280–2800 µatm pCO2). Calcification, total host protein and carbohydrate, chlorophyll a pigments, and symbiont cell density were quantified in order to characterize the acclimatory responses of each coral host and their symbionts to these global change stressors. Overall, forereef P. strigosa were more negatively affected by temperature, but not pCO2, in all aspects of physiology measured when compared to nearshore counterparts. This effect was observed at even the first timepoint, suggesting this forereef P. strigosa population will be negatively affected by long term heat events. In contrast, S. siderea did not appear to be negatively affected by heat, pCO2, or the interaction of the two stressors over the course of this experiment for any of the physiological responses considered. Our future work will incorporate transcriptomic comparisons of the same individuals to examine underlying molecular mechanisms driving these species and reef zone differences.
