抄録
The planktonic food web structure in the water off Cape Esan, southwestern Hokkaido, Japan was investigated at approximately one or two-month intervals from May 1997 through June 1999, based on biomass data of pico- (0.2–2 μm), nano- (2–10 μm), micro- (10–200 μm) and mesoplankton (200–20,000 μm). In spring (March–April), the water column was stratified and a spring diatom bloom occurred. In addition, microzooplankton and copepod biomass was high among the heterotrophic plankton in spring. In other seasons (summer, fall and winter), pico- and nanoplankton assemblages were dominant within the plankton community. These results indicate that the grazing food chain (micro-size phytoplankton – copepods) might be important and the indirect route (micro-size phytoplankton – microzooplankton – copepods) probably prevails in spring, while the microbial food web might be the predominant carbon flow route in other seasons.
