Seawater carbonate chemistry and calcifying fluid carbonate chemistry, calcification of coral

• Main Authors: Schoepf, Verena, Jury, Christopher P, Toonen, Robert J, McCulloch, Malcolm T
• Format: Dataset
• Language: English
• Published: PANGAEA 2017
• Subjects: Acid-base regulation; Alkalinity; total; Animalia; Aragonite saturation state; Benthic animals; Benthos; Bicarbonate ion; Boron/Calcium ratio; Calcification/Dissolution; Calcification rate of calcium carbonate; Calcifying fluid; carbonate ion; dissolved inorganic carbon; pH; Calcite saturation state; Calculated using seacarb after Nisumaa et al. (2010); Carbon; inorganic; dissolved; Carbonate system computation flag; Carbon dioxide; Cnidaria; Coast and continental shelf; Event label; EXP; Experiment; Experiment duration; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Identification; Kaneohe_Bay; Laboratory experiment; Montipora capitata; North Pacific; 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 change; Porites compressa; Ratio; Registration number of species; Salinity; Single species; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.891559; https://doi.org/10.1594/PANGAEA.891559

Ocean acidification (OA) is a pressing threat to reef-building corals, but it remains poorly understood how coral calcification is inhibited by OA and whether corals could acclimatize and/or adapt to OA. Using a novel geochemical approach, we reconstructed the carbonate chemistry of the calcifying fluid in two coral species using both a pH and dissolved inorganic carbon (DIC) proxy (delta 11B and B/Ca, respectively). To address the potential for adaptive responses, both species were collected from two sites spanning a natural gradient in seawater pH and temperature, and then subjected to three pHT levels (8.04, 7.88, 7.71) crossed by two temperatures (control, +1.5°C) for 14 weeks. Corals from the site with naturally lower seawater pH calcified faster and maintained growth better under simulated OA than corals from the higher-pH site. This ability was consistently linked to higher pH yet lower DIC values in the calcifying fluid, suggesting that these differences are the result of long-term acclimatization and/or local adaptation to naturally lower seawater pH. Nevertheless, all corals elevated both pH and DIC significantly over seawater values, even under OA. This implies that high pH upregulation combined with moderate levels of DIC upregulation promote resistance and adaptive responses of coral calcification to OA.