Seawater carbonate chemistry and acclimatization of a coral-dinoflagellate mutualism at a CO2 vent

• Main Authors: Prada, Fiorella, Franzellitti, Silvia, Caroselli, Erik, Cohen, Itay, Marini, Mauro, Campanelli, Alessandra, Sana, Lorenzo, Mancuso, Arianna, Marchini, Chiara, Puglisi, Alessia, Candela, Marco, Mass, Tali, Tassi, F, LaJeunesse, Todd C, Dubinsky, Zvy, Falini, Giuseppe, Goffredo, Stefano
• Format: Dataset
• Language: English
• Published: PANGAEA 2023
• Subjects: Alkalinity; total; Aragonite saturation state; Balanophyllia europaea; Benthos; Bicarbonate ion; Biomass/Abundance/Elemental composition; Calcite saturation state; Calculated using CO2SYS; Calculated using seacarb after Nisumaa et al. (2010); Carbon; inorganic; dissolved; Carbon/Nitrogen ratio; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Category; Chlorophyll a; Chlorophyll a per cell; CO2 vent; Coast and continental shelf; Effective quantum yield; Entire community; Field observation; Fluorescence; maximum; minimum; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Mediterranean Sea; Nitrogen; OA-ICC; Ocean Acidification International Coordination Centre; Other studied parameter or process; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); pH; Primary production/Photosynthesis; Rocky-shore community; Salinity; Site; Symbiont cell density; Temperate; Temperature; water; Time point; descriptive; Type; δ13C; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.957190; https://doi.org/10.1594/PANGAEA.957190

Ocean acidification caused by shifts in ocean carbonate chemistry resulting from increased atmospheric CO2 concentrations is threatening many calcifying organisms, including corals. Here we assessed autotrophy vs heterotrophy shifts in the Mediterranean zooxanthellate scleractinian coral Balanophyllia europaea acclimatized to low pH/high pCO2 conditions at a CO2 vent off Panarea Island (Italy). Dinoflagellate endosymbiont densities were higher at lowest pH Sites where changes in the distribution of distinct haplotypes of a host-specific symbiont species, Philozoon balanophyllum, were observed. An increase in symbiont C/N ratios was observed at low pH, likely as a result of increased C fixation by higher symbiont cell densities. δ13C values of the symbionts and host tissue reached similar values at the lowest pH Site, suggesting an increased influence of autotrophy with increasing acidification. Host tissue δ15N values of 0‰ strongly suggest that diazotroph N2 fixation is occurring within the coral tissue/mucus at the low pH Sites, likely explaining the decrease in host tissue C/N ratios with acidification. Overall, our findings show an acclimatization of this coral-dinoflagellate mutualism through trophic adjustment and symbiont haplotype differences with increasing acidification, highlighting that some corals are capable of acclimatizing to ocean acidification predicted under end-of-century scenarios.