PHOTOBIOLOGICAL STUDIES OF SKELETONEMA-COSTATUM ADAPTED TO SPECTRALLYDIFFERENT LIGHT REGIMES

Photoadaptational responses to three irradiances for each of five spec tral distributions of light were studied in the marine diatom Skeleton ema costatum. The C:Chl a ratio increased linearly with increased abso rption 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 c an easily be incorporated into mathematical models as simple functions by substituting absorbed light per unit Chl a for ambient irradiance.