Abundance, biomass and distribution of heterotrophic dinoflagellates during the North Atlantic spring bloom

摘要: The abundance, biomass, size and vertical distribution of heterotrophic (aplastidic) dinoflagellates were measured over several weeks in drogued water masses the northeast Atlantic Ocean. Sampling was conducted 1989 1990 vicinity 47–49°N 18–19°W as part JGOFS BOFS studies spring blooms oceanic waters. Two classes distinguished: 20 μm cells, quantified via Utermohl microscopy. Dinoflagellates an abundant component microzooplankton assemblages upper 200 m. In 1989, abundance ranged from 2 to 67 cells ml−1, equivalent 0.1–3.5 μgC l−1. Heterotrophic more 1990, with 13–414 0.9–18.3 Nanodinoflagellates ( cells. Estimates their grazing impact, derived literature data on growth rates conversion efficiencies, 8 (1989) 25% (1990) total primary production, up 52% <5 production. It is hypothesized that greatest impact may occur beneath mixed layer.