A steady state description ofgrowth and light absorption in the marine planktonic diatom Skeletonema costatum

Studies of the marine diatom Skel etonema costatum indicate that for a given irradiance and day length, increases in the rate of supply of a limiting nutrient cause linearly proportional increases in the growth rate and the Chl : C ratio. For a given irradiance, increases in day length cause decreases in the Chl : C ratio, and the growth rate is linearly proportional to the product of day length and the Chl : C ratio. For a given day length, increases in irradiance cause decreases in the Chl : C ratio and quantum yield, and the growth rate and irradiance are curvilinearly related. These observations are incorporated into a formulation of steady state growth, which includes day length, irradiance, and the Chl : C ratio, and two coefficients, which are the product of the maximal quantum yield and the specific absorption coefficient and the product of the average absorption cross section of the photosynthetic unit and the minimal rate of turnover of the unit. The photosynthetic quantum yield is represented by a Poisson distribution and is a function of irradiance alone.