Diurnal Migration of Plankton Crustacea

Abstract

The intensity of the sunlight and the turbidity of the water seem to be the predominant factors determining the vertical distribution of plankton. In a few cases, the change in temp. of the water in the metalimnion determines the upper or the lower limit of the vertical distribution. The physiological state of the animal must also be taken into consideration. Diurnal change of these factors, especially of intensity of sunlight, causes the periodical vertical migration. On the basis of the responses of animals to light intensity or temp. of water and on the basis of locomotor activity, various types of diurnal migration are recognized.