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The plankton community in the Polar Front area of the Barents Sea was investigated during a cruise from 14 to 28July 1987. The colonial algae Phaeocystis pouchetii and Dinobryon pellucidum dominated the phytoplankton. Depth integrated carbon assimilation rates varied from 190 to 810 mg C m -2 d-1. A high carbon:chlorophyll ratio (which varied from 123 to 352) prevailed at the three stations investigated, which may relate to facultative heterotrophic behaviour by D. pellucidum. The herbivorous zooplankton community was dominated by Calanus glacial&, C. finmarchicus, and C. hyperboreus. Maximum zooplankton biomass was found in the same depth strata as phytoplankton chlorophyll maximum. The herbivorous copepod populations did not display consistent day-night vertical migration patterns. Phytoplankton consumption rates of the various life stages were estimated from the turnover rate of plant pigments in the gut. The gut defecation rate constant (R) varied from 0.014 to 0.027rain -1 at 0°C in copepodites (Stage II to adult female) of C. glacial&, independent of developmental stage. Calanus spp. community carbon ingestion rates calculated from particulate carbon:chlorophyll ratios, were 10, 65 and 400% of daily phytoplankton carbon fixation rates at Stations 1, 2 and 3, respectively.

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