Grazing by zooplankton

The second factor, settling as aggregate bodies, has received a great deal of attention in recent studies. The primary mechanism for aggregation of coccoliths has been clearly shown to be grazing by zooplankton and encapsulation in fecal matter. The general model of Honjo (1976) for this complex process is presented in Figure 4.14. Notice that several processes are involved before discrete coccoliths are susceptible to solution in deep water. Honjo s paper and that of Schneidermann (1977) both present detailed discussions of coccolith distribution and sedimentation. 

The duration of the spring bloom is limited by nutrient availability and/or grazing by zooplankton. Phytoplankton growth and abundance then decline to lower levels, which are maintained throughout the summer by nutrient recycling within the euphotic zone. In some locations, limited mixing in autumn can stimulate another small bloom, before deep winter mixing returns the system to its winter condition. 

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