A field technique for the determination of zooplankton grazing on natural bacterioplankton

SUMMARY. 1. A method for the determination of zooplankton community grazing rates on natural populations of bacteria is described. 2. Undisturbed zooplankton samples were incubated with 3H‐thymidine‐labelled bac teriioplankton, and animals and their food subsequently separated by size. 3. Prehandling of zooplankton by concentration before incubation reduce the grazing rates by a factor ranging from three to four. 4. Time series experiments showed that appropriate incubation periods ranged from 40 min at 14°C to 60 min at 10°C. 5. Spatial variability in the zooplankton was the main source of the overall standard error. This was considerably reduced by using composite samples.