60-135μM during and at the beginning of the bloom: 28-45μM during the peak of the bloom: 45μM afterwards μM
||Kranz SA, Young JN, Hopkinson BM, Goldman JA, Tortell PD, Morel FM. Low temperature reduces the energetic requirement for the CO2 concentrating mechanism in diatoms. New Phytol. 2015 Jan205(1):192-201. doi: 10.1111/nph.12976 p.195 right columnPubMed ID25308897
||Young JN, Goldman JA, Kranz SA, Tortell PD, Morel FM. Slow carboxylation of Rubisco constrains the rate of carbon fixation during Antarctic phytoplankton blooms. New Phytol. 2015 Jan205(1):172-81. doi: 10.1111/nph.13021PubMed ID25283055
||Primary source abstract: "[Investigators] measured carbon fixation rates, protein content and Rubisco abundance and catalytic rates during an intense diatom bloom in the Western Antarctic Peninsula (WAP) and in laboratory cultures of a psychrophilic diatom (Fragilariopsis cylindrus)."
||P.195 right column: "In order to quantify the CO2 concentration at the site of fixation by the enzyme Rubisco in the species that dominate carbon fixation, it is necessary to know the half‐saturation constant, KC, of the enzyme for its substrate CO2 in the ambient phytoplankton population. As shown in a companion study by Young et al. (primary source), KC values of Rubisco (from mesophilic and psychrophilic diatoms) measured at 0°C are c. 15 μM, lower than the air saturated CO2 concentration at that temperature. Using this KC, [investigators] calculate CO2 concentrations at the site of fixation between 60 and 135 μM during and at the beginning of the bloom, 28–45 μM during the peak of the bloom, and an average of 45 μM afterwards (Fig. 1d)."