ABSTRACT
Planklonic protozoa function as important trophic intermediaries in pelagic food webs by repackaging small bacterial and algal cells into food items which are accessible to larger consumers such as calanoid copepods. More studies employing natural prey assemblages have demonstrated that calanoid copepods consume Protozoa under field, as well as laboratory, conditions and that they do so at rates and in quantities which are physiologically meaningful to the consumer organisms and demographically meaningful to the prey populations. The protocol described was designed to measure clearance and ingestion rates of marine calanoid copepods on Protozoa by monitoring changes in natural assemblages of microplankton. Turbulence destroys some protozoans and should be avoided while draining; the siphon tube should contact the bottom of the receiving vessel so that water is transferred into water rather than into air. Protozoan carbon content is calculated from empirically derived, volume-specific relationships for particular taxa.
