Chromatic Adaptation in Relation to Color and Depth Distribution of Freshwater Phytoplankton and Large Aquatic Plants

Abstract

The theory known as chromatic was first suggested by Engelmann ('83), who based it on the results of his own investigations and on the color stratification of large marine algae observed by Qrsted ('44). According to this theory, the color distribution of these algae represents an adaptation to the differences in the spectral composition of the solar energy penetrating to the different depths. The green algae grow in the upper water where red rays dominate and red forms grow in the deeper strata where green light is dominant, with brown forms in the intermediate strata where intermediate spectral colors predominate. The differences in the colors present in the algae thus enable them to more readily absorb the dominant rays in the solar radiation at the various depths. During the sixty years that have elapsed since the announcement of this theory, it has served as a stimulus for a considerable number of investigations important r6le in the formation of the dealing with the light relations of aquatic plants. While the marine algae played an theory, they were soon superseded by freshwater forms as subjects for experimental work, including various species of Myxophyceae and Chlorophyceae. In