Summary
1. Mathematical descriptions of uniform and non- uniform phytoplankton grazing by zooplankton are presented and equations for calculating the dependence of phytoplankton production on rate and rhythm of elimination are deduced.
2. of greatest interest is non-uniform phytoplankton grazing, which is reflected in a sinusoidal eurve and is usually found in a bath eco- system with migratory consumers
3. Phytoplankton production depends upon the time of grazing; the nearer towards nightfall grazing oceurs, the higher is the phytoplankton production.
4. In order to be able to calculate the phyto- plankton production and the amount of food consumed under conditions of non-uniform sinusoidal grazing,