Cultures:\u00a0Pleurochrysis\u00a0carterae\u00a0cultures were maintained in exponential growth phase under axenic conditions in semi-continuous batch culture using L1-Si media prepared on 0.2 um-filtered, UV-sterilized, autoclaved seawater.\u00a0 Cultures were acclimated to one of three\u00a0pCO2\u00a0treatments for > 9 generations before experiments were performed.\u00a0 Cultures were maintained in an incubator at 16.5 +/- 0.5 degrees C and 470 umol photons/m-2/s\u00a0PAR on a 14-10 light-dark cycle.
\npCO2\u00a0Treatments: Carbonate chemistry was manipulated by bubbling cultures and prepared media with 500 mL/min\u00a0with 0.2 um-filtered 280, 380, or 750 ppm\u00a0pCO2\u00a0air.\u00a0 The\u00a0pCO2\u00a0levels of the treatment air were established using two mass flow controllers (Aalborg, Orangeburg, NY, USA) for each treatment to precisely mix in-house compressed air and pure CO2\u00a0(Maine Oxy, Auburn, ME, USA).\u00a0 The in-house compressed air was stripped of CO2\u00a0to less than 10 ppm CO2\u00a0using a Puregas VCD CO2\u00a0Adsorber (Puregas, LLC, Broomfield, CO, USA).\u00a0 The\u00a0pCO2\u00a0of the gas mixtures was stable to +/- 8 ppm.\u00a0\u00a0pCO2\u00a0values of the cultures may be different than the target levels due to biological activity.
\nGrowth rate measurements:\u00a0 At the same time each day, the cell density of each\u00a0pCO2\u00a0treatment culture was measured in order to calculate the growth rate.\u00a0 The data analyzed represent three consecutive growth cycles.
\nCell density:\u00a0Culture density was measured using a Moxi Z mini automated cell counter (ORFLO Technologies, Ketchum, ID, USA), which has a coefficient of variation of 4%.
Experimental results describing the growth rate of\u00a0Pleurochrysis carterae\u00a0(NCMA strain 645). It was isolated from\u00a041.525 degrees North, 70.6736 degrees West (Woods Hole, Massachusetts USA), but has been maintained in culture since 1958.
Growth Rate:\u00a0 Growth rate (u) with units d-1\u00a0(per day) was calculated using the Excel function LINEST, which calculates the statistics for a line by using the \u2018least squares\u2019 method to calculate a straight line that best fits the data. \u00a0
\nThe equation for the line is:\u00a0 y =\u00a0mx\u00a0+ b. \u00a0 \u00a0
\nThe syntax is:\u00a0 LINEST(known_y\u2019s, [known_x\u2019s], [const], [stats])
\nIn this case, the \u2018known_y\u2019s\u2019 were the ln(cell density); the \u2018known_x\u2019s\u2019 were the days of the growth cycle; [const] was set to \u2018TRUE\u2019 which calculates the intercept (b) instead of forcing it to zero; and [stats] was set to \u2018TRUE\u2019 in order to return the regression statistics of the line.
\nThe slope of the line represents the growth rate for the given growth cycle and is analogous to using the standard growth rate equation, except that it incorporates all data points during the growth cycle, not simply the first (0) and last (n) data points.
\nDMO notes:
\n- added underscores and removed spaces and units from column names
\n- changed column names to comply with BCO-DMO standards.
\n- replaced all \"na\" with \"nd\"