Coastal sands are biocatalytic filters for dissolved and particulate organic matter of marine and terrestrial origin. In this study, we accessed the variability of benthic bacterial communities over two annual cycles in Isfjorden (Svalbard, 78°N) sediments, where primary production does not occur during winter. Sandy sediment samples were obtained with a Van Veen grab. Benthic community structure in surface sediments (0-2 cm depth) was studied on the level of cell counts (DAPI staining, CARD-FISH) and 16S rRNA-based taxonomy (16S rRNA gene sequencing using primers S-D-Bact-0341-b-S-17 and S-D-Bact-0785-a-A-21, Illumina sequencing platform HiSeq2500, 2x250 bases, paired-end). Prior to DAPI staining and CARD-FISH, formaldehyde-fixed Svalbard sediment samples were sonicated on ice with a type MS2.5 probe (Sonoplus mini20; Bandelin, Berlin, Germany). Six sonication steps were done at a setting of 30 s, an amplitude of 86% and pulse of 0.2 s. Combined supernatants were filtered onto 0.2 µm pore size polycarbonate filters (GTTP, Millipore, Eschborn, Germany). Total organic carbon, total carbon, total organic nitrogen and total nitrogen contents were determined using 25-50 mg of freeze-dried sediments. To determine organic carbon, inorganic carbon was removed with 1 M HCl before analysis. Samples were analyzed in an Euro EA-CNS elemental analyser (HEKAtech, column temperature 75°C; carrier gas helium at 80 ml min-1, reactor temperature 1000°C with oxygen flow 10 ml min-1, oxidation time 7.9 sec) with thermal conductivity detection. Calibration was done with sulfanilamide (0.2 to 2 mg) standards.