Seawater carbonate chemistry and Phaeocystis pouchetii's responses to temperature (2 vs. 6 °C), light (55 vs. 160 µmol photons m-2 s-1) and pCO2 (400 vs. 1000 µatm)

We assessed the responses of solitary cells of Arctic Phaeocystis pouchetii (Strain PS78) grown under a matrix of temperature (2°C vs. 6°C), light intensity (55 vs. 160 μmol photons m-2 s-1) and CO2 partial pressures (pCO2; 400 vs. 1000 μatm). Before the experiments, the strain (isolated during Polarstern cruise PS78 in 2011) was kept as stock culture at 1° in 0.2 µm sterile-filtered Arctic seawater (Salinity 33), enriched with vitamins and trace metals according to F/2 medium (Guillard & Ryther, 1962). Nitrate and phosphate were added in concentrations of 100 and 6 µmol L-1, respectively. Experiments were conducted between May 2016 and September 2017 at the Alfred-Wegener-Institute, using standardized media and continuous light exposition. Next to acclimation parameters (growth rates, particulate and dissolved organic carbon and nitrogen, chlorophyll a content), we measured physiological processes in-vivo (electron transport rates and net photosynthesis) using fast-repetition rate fluorometry and membrane-inlet mass spectrometry. In order to allow full comparability with other ocean acidification data sets, the R package seacarb (Gattuso et al, 2022) was used to compute a complete and consistent set of carbonate system variables, as described by Nisumaa et al. (2010). In this dataset the original values were archived in addition with the recalculated parameters (see related PI). The date of carbonate chemistry calculation by seacarb is 2024-01-20.