Fig. 1. Theoretical dependence of phytoplankton standing stock upon non-uniform grazing during 24 h. (1) Increase of standing stock through lack of grazing; (2) variations in grazing rate; (3) resulting curve of variations in standing stock
In other words, the amplitude for the grazing curve is in proportion to the initial standing stock.
To determine the grazing rate q, Eqs. (2) and(4) can be used. We then get the following expression for q
Total grazing of phytoplankton Q for the period t-t is
=Non-uniform grazing is
À widespread in the bathyplankton ecosystem. However, due to the prevalence of migratory zooplankton species in the bath the main grazing of phytoplankton occurs at night only. Moreover, as has already been pointed out, the phytoplankton standing stock B0 from which grazing begins, increases considerably as the phytoplankton have time to increase in biomass during daytime Hence