Temperature modulates coccolithophorid sensitivity of growth, photosynthesis and calcification to increasing seawater pCO2

• Main Authors: Sett, Scarlett, Bach, Lennart Thomas, Schulz, Kai Georg, Koch-Klavsen, Signe, Lebrato, Mario, Riebesell, Ulf
• Format: Dataset
• Language: English
• Published: PANGAEA 2014
• Subjects: Alkalinity; total; Aragonite saturation state; Bicarbonate ion; Bottles or small containers/Aquaria (<20 L); Calcification/Dissolution; Calcite saturation state; Calculated; Calculated using CO2SYS; Calculated using seacarb after Nisumaa et al. (2010); Carbon; inorganic; dissolved; particulate; production per cell; organic; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Chromista; Emiliania huxleyi; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Gephyrocapsa oceanica; Growth/Morphology; Growth rate; Haptophyta; Laboratory experiment; Laboratory strains; North Atlantic; OA-ICC; Ocean Acidification International Coordination Centre; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Particulate inorganic carbon/particulate organic carbon ratio; Pelagos; pH; Phytoplankton; Potentiometric titration; Primary production/Photosynthesis; Salinity; Single species; Species; Temperature; water; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.835214; https://doi.org/10.1594/PANGAEA.835214

Increasing atmospheric CO2 concentrations are expected to impact pelagic ecosystem functioning in the near future by driving ocean warming and acidification. While numerous studies have investigated impacts of rising temperature and seawater acidification on planktonic organisms separately, little is presently known on their combined effects. To test for possible synergistic effects we exposed two coccolithophore species, Emiliania huxleyi and Gephyrocapsa oceanica, to a CO2 gradient ranging from ~0.5-250 µmol/kg (i.e. ~20-6000 µatm pCO2) at three different temperatures (i.e. 10, 15, 20°C for E. huxleyi and 15, 20, 25°C for G. oceanica). Both species showed CO2-dependent optimum-curve responses for growth, photosynthesis and calcification rates at all temperatures. Increased temperature generally enhanced growth and production rates and modified sensitivities of metabolic processes to increasing CO2. CO2 optimum concentrations for growth, calcification, and organic carbon fixation rates were only marginally influenced from low to intermediate temperatures. However, there was a clear optimum shift towards higher CO2 concentrations from intermediate to high temperatures in both species. Our results demonstrate that the CO2 concentration where optimum growth, calcification and carbon fixation rates occur is modulated by temperature. Thus, the response of a coccolithophore strain to ocean acidification at a given temperature can be negative, neutral or positive depending on that strain's temperature optimum. This emphasizes that the cellular responses of coccolithophores to ocean acidification can only be judged accurately when interpreted in the proper eco-physiological context of a given strain or species. Addressing the synergistic effects of changing carbonate chemistry and temperature is an essential step when assessing the success of coccolithophores in the future ocean.