UNDER EMBARGO - This dataset is part of BE/2023 sampling campagn in SW Greenland fjords (Igaliku and Tunulliarfik). Pelagic community was analysed using Imaging Flow Cytometry (iFCM) with an ImageStream®X Mk II. Cells were grouped into functional size classes—pico-, nano- and microplankton—according to measured cell length. Cells lacking chlorophyll autofluorescence were classified as heterotrophic or chemotrophic organisms, including heterotrophic picoplankton/bacteria (HP; ≤2 µm) and heterotrophic nanoplankton (HN; 2–20 µm). No larger heterotrophs (>20 µm) were visually detected. Autofluorescent cells were considered phototrophic, although this fraction may also include mixotrophic taxa, and comprised picophytoplankton (AP; ≤2 µm), nanophytoplankton (AN; 2–20 µm), and microphytoplankton (AMicro; 20–100 µm). To estimate the biovolume of each plankton class, the two-dimensional cell surface area measured by the IDEAS® imaging software was multiplied by the mean cell width, assuming that cell width approximates the third spatial dimension. Carbon biomass was subsequently derived from biovolume using established carbon–volume relationships. For the HP fraction, carbon content was estimated using the bacterial conversion proposed by Romanova and Sazhin (2010), where volume is expressed in µm³. Although the HP fraction may also include heterotrophic picoeukaryotes, and its biomass may therefore be partly underestimated, this conversion was applied because the fraction was assumed to be numerically dominated by bacteria. For the other protist groups, carbon biomass was derived following Menden-Deuer and Lessard (2000). Carbon values were converted from pg C cell⁻¹ to carbon biomass (µg C L⁻¹) based on cell abundance.

UNDER EMBARGO - This dataset originates from the BE/2023 sampling campaign conducted in southwest Greenland fjords (Igaliku and Tunulliarfik) and quantifies grazing impacts by micro- and mesozooplankton on phytoplankton and heterotrophic microbial communities (including bacteria) in two fjord systems characterized by contrasting glacial regimes. Grazing and microbial growth rates were estimated using two-point dilution experiments (two-point dilution experiments), alongside experiments assessing mesozooplankton and copepod grazing on both phytoplankton and microzooplankton. Community responses were resolved using imaging flow cytometry, enabling the identification of plankton functional groups (autotrophic, mixotrophic, and heterotrophic) and size classes. The dataset also includes measurements of chlorophyll a variability determined by high-performance liquid chromatography. Overall, the dataset supports analyses of trophic interactions and grazing dynamics across the microbial food web under differing glacier-influenced environmental conditions.