Photosynthetic rates during two-hour intervals during the photoperiod were calculated by solving the differential equation

d(PC)/dt = P – D x PC (1)

where P is the rate of production of PC in the growth chamber, D is the dilution rate of the growth chamber and d(PC)/dt is the rate of change of PC in the growth chamber. The solution of equation (1) between two points in time is

P = D(PC_t – PC₀ exp(–Dt)) /(1 – exp(–Dt) ) (2)

where PC₀ and PC_t are the concentrations of PC at the beginning and end of the time interval, respectively, and t is the duration of the time interval, which in this experiment was 2 hours. Values of P were calculated for each two-hour time interval during the photoperiod, normalized to the chlorophyll a concentration during each time interval, and then averaged to determine the photosynthetic rate per unit chlorophyll (productivity index or PI) during the photoperiod. Results are reported as grams of carbon per gram of chlorophyll a per hour averaged over the 14-h photoperiod.

Dark respiration rates were calculated from the natural logarithm of the ratio of the PC concentration at the end of the photoperiod and the beginning of the subsequent photoperiod. The natural logarithm of the ratio of the PC concentrations was equated to (D + D_r)10/24, where D_r is the dark respiration rate (with units of inverse days) and D is the dilution rate (with units of inverse days). Division by 24 converts these rates to hourly rates, and multiplication by 10 corrects for the fact that the duration of the dark period was 10 hours. Thus

D_r = (24/10)ln (PC_e/ PC_b) – D (3)

where PC_e and PC_b are the PC concentrations at the end of one photoperiod and the beginning of the next photoperiod, respectively.

BCO-DMO Processing Notes:
- added conventional header with dataset name, PI name, version date
- modified parameter names to conform with BCO-DMO naming conventions
- removed two rows that contained a mean and stdev for 'relative growth rate' (growth_relative)
- moved the stdev and n (number of values in mean) for 'growth rate per day' (growth_day) to another column and called it 'growth_stdev_n'
- reformatted date from yyyy.m.d to yyyy-mm-dd