Grazing pressure of the size-fractionated copepod community on phytoplankton in the coastal waters and the northern East China Sea

Abstract

Grazing pressures of the size-fractionated copepod community on phytoplankton were investigated using the food removal method in the coastal water (May 2012 and June 2013) and the northern East China Sea (June 2012, May 2013). Grazing pressure of total copepod community on phytoplankton were 0.03~9.02% in the coastal waters and 0.09~3.70% in the northern East China Sea in 2012. In 2013, the grazing pressure were 0.14~13.27% and 0.03~7.66% in the coastal waters and in the northern East China Sea, respectively. Ingestion rates of the copepods on phytoplankton increased with increasing copepod size groups. The grazing pressure of the copepod community in the field, however, was higher in the small-sized copepod group than that of the macro-sized copepod group. Our studies suggested that the small-sized copepod community was more important to control phytoplankton standing crops than the macro-sized copepod community.ure of total copepod community on phytoplankton were 0.03~9.02% in the coastal waters and 0.09~3.70% in the northern East China Sea in 2012. In 2013, the grazing pressure were 0.14~13.27% and 0.03~7.66% in the coastal waters and in the northern East China Sea, respectively. Ingestion rates of the copepods on phytoplankton increased with increasing copepod size groups. The grazing pressure of the copepod community in the field, however, was higher in the small-sized copepod group than that of the macro-sized copepod group. Our studies suggested that the small-sized copepod community was more important to control phytoplankton standing crops than the macro-sized copepod community.