Abstract:

Microzooplankton play an important role in marine food web. In order to clarify grazing impact of microzooplankton on phytoplankton, dilution incubations were carried out in Southern Ocean and temperate sea area during austral summer, 2012-2013. Results showed that microzooplankton grazing rates were in the range of 0.07d^-1–1.29d^-1, while phytoplankton growth rate were 0.04d^-1–0.89d^-1. Accordingly, 6.4%–72.5% of the phytoplankton stock and a high range of 14%–776.9% primary production were grazed by microzooplankton. Although the microzooplantkon grazing rates might be overestimated, microzooplankton have a significant role in controlling phytoplankton in Southern Ocean and temperate sea area in austral summer.

Key words: Southern Ocean, temperate sea area, microzooplankton, phytoplankton, grazing impact