Grazing pressure of the size-fractionated copepod community on phytoplankton and protozoan preys at a fixed station, southeastern coast of Korea

Abstract

Copepods are important component of marine zooplankton, grazing on phytoplankton and protozoan preys and affecting energy flow in marine food webs. Species-level grazing rates have known useful information in feeding ecology of copepods. Considering the high species diversity of copepods, however, measuring the feeding rates of various kinds of copepod species is not practical. So, measurement of feeding rates in copepod community is a good alternative approach to understand the effect of copepod community on phytoplankton and protozoan preys. We measured feeding rates of the size-fractionated copepods on phytoplankton and protozoan preys at a fixed station off Tong-young city, southeastern coast of Korea, from February to December 2013 bimonthly. Copepods were size-fractionated into the three groups (i.e. 200-500μm, 500-1000μm, and 1000-2000μm) using sieve, and incubated in surface water for 24hrs. Prey concentrations were measured before and after incubation. The feeding rates were calculated by Frost equation (1972). We will discuss the seasonal variation of grazing pressure of the size-fractionated copepods on phytoplankton and protozoan preys, and evaluate the importance of both diets for the size-fractionated copepod community in the marine ecosystem.nsidering the high species diversity of copepods, however, measuring the feeding rates of various kinds of copepod species is not practical. So, measurement of feeding rates in copepod community is a good alternative approach to understand the effect of copepod community on phytoplankton and protozoan preys. We measured feeding rates of the size-fractionated copepods on phytoplankton and protozoan preys at a fixed station off Tong-young city, southeastern coast of Korea, from February to December 2013 bimonthly. Copepods were size-fractionated into the three groups (i.e. 200-500μm, 500-1000μm, and 1000-2000μm) using sieve, and incubated in surface water for 24hrs. Prey concentrations were measured before and after incubation. The feeding rates were calculated by Frost equation (1972). We will discuss the seasonal variation of grazing pressure of the size-fractionated copepods on phytoplankton and protozoan preys, and evaluate the importance of both diets for the size-fractionated copepod community in the marine ecosystem.