Meeting Abstract
Predicting the response of marine species to future ocean acidification (OA) is key to anticipating future ecological impacts of ocean change. However, forecasting ecosystem changes is difficult due to variation among species and individuals in their response to this stressor. Many OA studies extrapolate the response of one population to the entire species, but a single population may not be representative if the species spans a heterogeneous geographic range. This study compares the response of two populations of the coral, Balanophyllia elegans from California, to future OA conditions. These two populations experience distinct upwelling regimes, which bring acidified water to the surface. To endure upwelling, populations of B. elegans must be plastic to fluctuating pH, but the lower limits of their pH tolerance may differ according to their environment’s upwelling regime. We measured gene expression and respiration rates in corals from both populations exposed to pCO2 levels of 750 and 2000 µatm for four weeks. Corals from the northern population, which experience lower pH in their natural habitat, maintained the same respiration rate throughout the exposure, suggesting resilience to future pH levels. In contrast, corals from the southern population showed an increase in respiration rate throughout the exposure to low pH, suggesting an increased metabolic demand. Higher tolerance to low pH conditions in B. elegans’ northern range may provide an evolutionary step towards maintaining important processes of high metabolic demand in the face of future OA. Using RNASeq data collected at three time points (day 0, 9, and 29) we will compare changes in gene expression throughout the exposure and between populations, thus identifying genomic mechanisms of resilience to future OA.
