The Adaptation of Plankton Algae IV. Light Adaptation in Different Algal Species.

Two types with regard to adaptation to different light intensities are described: tbe Chlorella type and the Cyclotella type. The Chlorella type is mostly found among the green algae, the Cyclotella type among the diatoms. The Chlorella type adapts to a new light intensity mainly by changing the pigment content. Therefore the cells adapted to a high light intensity have a lower chlorophyll a content per cell than cells adapted to a low light intensity. Light saturation is mostly rather low for cells adapted to low light intensities. The light-saturated rate of photosynthesisist mostly lower for cells adapted to a high light intensity than for cells adapted to a low light intensity. The actual photosynthesis is not much higher at a high light intensity than at a low one. The actual photosynthesis is the photosynthesis at the light intensity where the cells are grown. - The Cyclotella type adapts only by changing the light-saturated rate. The chlorophyll content is the same in cells grown at low and high light intensities. Light saturation for cells grown at a low light intensity is rather high. The light-saturated rate is much higher in the case examined at the high light intensity than at the low one. The actual photosynthesis is considerably higher for cells grown at the high light intensities than for cells grown at low light intensities.- The two adaptation types are not sharply separated since transition types occur.