PHOTOBIOLOGICAL STUDIES OF SKELETONEMA-COSTATUM ADAPTED TO SPECTRALLY DIFFERENT LIGHT REGIMES

Photoadaptational responses to three irradiances for each of five spectral distributions of light were studied in the marine diatom Skeletonema costatum. The C:Chl a ratio increased linearly with increased absorption of light per unit Chl a within the range of irradiances studied. The quantum yield for growth decreased monotonically with increased absorption of light. Our results imply that photoadaptational changes in the C:Chl a ratio and in the maximum quantum yield for growth of S. costatum are simple functions of the number of absorbed photons. Thus, spectrally dependent photoadaptational changes in these parameters can easily be incorporated into mathematical models as simple functions by substituting absorbed light per unit Chl a for ambient irradiance.