Meeting Abstract
Global change is threatening coral reefs, with rising temperatures leading to repeat bleaching events (dysbiosis of coral hosts and symbiotic algae) and increasing pCO2 causing reductions in calcification. Global bleaching events reveal fine-scale patterns of coral survival; however, the traits that lead to success under stress remain elusive. We conducted a 95-day laboratory experiment to investigate the physiological responses of two Caribbean reef-building coral species (Siderastrea siderea and Pseudodiploria strigosa) from two distinct reef zones on the Belize Mesoamerican Barrier Reef System under ocean warming (28, 31°C), acidification (~400–2800 µatm), and the combination of the two. Calcification, total host protein and carbohydrate, Chlorophyll a pigment, and symbiont cell density were quantified every 30 days to characterize the acclimatory responses of each coral genotype and their symbionts. Holobiont physiology of the two species was differentially affected by these stressors, and changed over time. While S. siderea was more negatively affected by increased pCO2, P. strigosa was more negatively impacted by elevated temperature, particularly after chronic exposure. Reef zone differences in calcification and total protein were also apparent in P. strigosa in response to experimental treatment. By tracking holobiont physiology through time, this experiment highlights that focusing on average trends over the experimental interval can obscure the complexity of corals’ responses through time, and provides a framework for future studies to consider when investigating such long-term acclimatory responses.
