Type-3 functional response in limnetic suspension-feeders, as demonstrated by in situ grazing rates

Abstract

Field-measured grazing rates (ml/animal/d) of cladocerans (mostly daphniids) and diaptomids were assembled from various published studies and plotted as a function of corresponding phytoplankton concentration (µg l−1 f.w.). Filtering rates of both zooplankton groups initially increased with seston concentration until maximal grazing rates were observed at approximately 4 × 102 and 1 × 102 µg l−1 for cladocerans and copepods, respectively; at higher algal concentrations, filtering rates of both declined as a function of food concentration. The shape of these curves are most consistent with Holling's (1966) Type 3 functional response.