Samples for single cell abundances as an estimate for the abundance of benthic bacteria on the Northeast Greenland shelf have been collected with R/V Polarstern during PS109 between September and October 2017 using a camera-equipped multiple corer (TV-MUC; core area 0.007 m²). Upon arrival on deck, the upper 5 cm of three MUC cores were sliced into 1 cm layers with a 10 ml cut-off syringe. 2 ml of each slice was transferred into a scintillation vial and fixed with 2 % filtered formaldehyde-seawater solution. In the laboratory, the samples were diluted, filtered through polycarbonate filters (0.2 µm, Whatman Nucleopore Track-Etch Membrane) and stained with a 0.001 % acridine orange solution after Hobbie et al., 1977 (doi:10.1128/aem.33.5.1225-1228.1977). Cells were counted on at least 30 grids (125 µm * 125 µm area) for 2 replicate filters per sample each with a Zeiss Axiophot microscope (Germany) and a 100x oil immersion objective lens (Zeiss Plan-Apochromat, Germany).

Single cell abundances were calculated with the following equation:single cell abundance (cell number ml-1 sediment-1) = average cell count * (filtration funnel area/grid area) * dilutionwherefiltration funnel area = 203077576 µm²grid area = 15625 µm²dilution=4830 µl