Constraints on coccolithophores under ocean acidification obtained from boron and carbon geochemical approaches

• Published in: Geochimica et Cosmochimica Acta
• Main Authors: Liu, Yi-Wei, Rokitta, Sebastian, Rost, Björn, Eagle, Robert
• Other Authors: Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan, Alfred Wegener Institute for Polar and Marine Research (AWI), ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2021
• Subjects: Boron isotopes; Carbon isotopes; Coccolithophores; Ocean acidification; [SDE]Environmental Sciences; [SDU]Sciences of the Universe [physics]
• Online Access: https://hal.univ-brest.fr/hal-03452046; https://hal.univ-brest.fr/hal-03452046/document; https://hal.univ-brest.fr/hal-03452046/file/1-s2.0-S0016703721005676-main.pdf; https://doi.org/10.1016/j.gca.2021.09.025

International audience Ocean acidification (OA) appears to have diverse impacts on calcareous coccolithophores, but the cellular processes underlying these responses are not well understood. Here we use stable boron and carbon isotopes, B/Ca ratios, as well as inorganic and organic carbon production rates to investigate the carbon utilization and the internal pH regulation at the site of calcification in Emiliania huxleyi, Calcidiscus leptoporus and Pleurochrysis carterae cultured over a wide pCO2 range (180–1000 μatm). Despite large variability, the geochemistry data indicate species-specific modes of pH control and differences in the utilization of inorganic carbon. Boron isotope data suggest that all three species generally upregulate the pH of the calcification fluid (pHCF) compared to surrounding seawater, which coincides with relatively constant growth rates and cellular ratios of inorganic to organic carbon. Furthermore, species exhibit different strategies in regulating their pHCF, i.e., two species maintain homeostasis (pHCF = ∼8.7), while one species shows a constant offset to the surrounding seawater (ΔpH = ∼0.6 units) over the entire tested pCO2 range. In addition to these different strategies, carbon isotope data suggests that high plasticity in the utilization of dissolved inorganic carbon might be an explanation for species-specific differences in coccolithophore responses to OA.