Seawater carbonate chemistry and calcification in the temperate coral Turbinaria reniformis

• Main Authors: Ross, Claire Louise, Schoepf, Verena, DeCarlo, Thomas M, McCulloch, Malcolm T
• Format: Dataset
• Language: English
• Published: PANGAEA 2018
• Subjects: Acid-base regulation; Alkalinity; total; Animalia; Aragonite saturation state; Benthic animals; Benthos; Bicarbonate ion; Boron/Calcium ratio; Bremer_Bay; Calcification/Dissolution; Calcification rate; standard error; Calcifying fluid; carbonate ion; dissolved inorganic carbon; Calcite saturation state; Calcium; Calculated using seacarb after Nisumaa et al. (2010); Carbon; inorganic; dissolved; Carbonate system computation flag; Carbon dioxide; Cnidaria; Coast and continental shelf; Coelomic fluid; pH; DATE/TIME; EXP; Experiment; Field observation; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Indian Ocean; Location; OA-ICC; Ocean Acidification International Coordination Centre; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Photochemical efficiency; Primary production/Photosynthesis; Ratio; Registration number of species; Indian; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.924614; https://doi.org/10.1594/PANGAEA.924614

High-latitude coral reefs provide natural laboratories for investigating the mechanisms and limits of coral calcification. While the calcification processes of tropical corals have been studied intensively, little is known about how their temperate counterparts grow under much lower temperature and light conditions. Here, we report the results of a long-term (2-year) study of seasonal changes in calcification rates, photo-physiology and calcifying fluid (cf) chemistry (using boron isotope systematics and Raman spectroscopy) for the coral Turbinaria reniformis growing near its latitudinal limits (34.5° S) along the southern coast of Western Australia. In contrast with tropical corals, calcification rates were found to be threefold higher during winter (16 to 17° C) compared with summer (approx. 21° C), and negatively correlated with light, but lacking any correlation with temperature. These unexpected findings are attributed to a combination of higher chlorophyll a, and hence increased heterotrophy during winter compared with summer, together with the corals' ability to seasonally modulate pHcf, with carbonate ion concentration [CO32-]cf being the main controller of calcification rates. Conversely, calcium ion concentration [Ca2+]cf declined with increasing calcification rates, resulting in aragonite saturation states Ωcf that were stable yet elevated fourfold above seawater values. Our results show that corals growing near their latitudinal limits exert strong physiological control over their cf in order to maintain year-round calcification rates that are insensitive to the unfavourable temperature regimes typical of high-latitude reefs.