Diurnal Study of Phytoplankton Pigments, an In Situ Study in East Sound, Washington

Abstract

The effect of light intensity on the quantities of chlorophyll and carotenoid pigments in a natural marine diatom community has been observed.Marked daily lluctuations in the quantities of these pigments, which showed highest concentrations around mid.day and at night, resulted from changes in quantities within the cells.Rates of synthesis and decomposition throughout the day have been computed.Highest cellular concentrations of chlorophyll and carotenoid pigments corre sponded to optimal light intensities for photosynthesis.The differential effect of light on chlorophyll a and on carotenoid pigments, where chlorophyll changes are more extreme, caused the ratios of these pigments to change during the day.The significance of this change is discussed.