The importance of the time factor in the response of zooplankton to varying concentrations of naturally occurring particulate matter 1

Abstract

Over the course of a year a linear relationship was found between feeding rates of five species of neritic copepods and their probable food supply, the naturally occurring particulate matter. However, a saturation‐type curve was obtained when a range of food concentration was offered to Pseudocalanus minutus over a short period of time (18–20 h). Digestive enzyme levels of the copepod population were also found to vary linearly on a seasonal basis. The affinity (1/ K m ) appeared to vary with time, indicating acclimation in the digestive system. A new model, linear for variations of food concentrations over an extended period of time (weeks to a year) and curvilinear for variations over a time smaller than the one needed for acclimation, is developed.