Vol.:(0123456789) 1 3 Polar Biology (2021) 44:361–378 https://doi.org/10.1007/s00300-020-02798-w ORIGINAL PAPER Short‑term dynamics of nutrients, planktonic abundances, and microbial respiratory activity in the Arctic Kongsforden (Svalbard, Norway) M. Azzaro 1  · S. Aliani 2  · G. Maimone 1  · F. Decembrini 1  · C. Caroppo 3  · F. Giglio 4  · L. Langone 4  · S. Miserocchi 4  · A. Cosenza 1  · F. Azzaro 1  · A. C. Rappazzo 1  · A. S. Cabral 6,7  · R. Paranhos 7  · M. Mancuso 5  · R. La Ferla 1 Received: 5 September 2019 / Revised: 28 December 2020 / Accepted: 30 December 2020 / Published online: 21 January 2021 © The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature 2021 Abstract Atlantifcation of Arctic ocean is causing a sharp increase in temperature and salinity around Svalbard Islands and in Kongs- forden. Such phenomenon and the input of sediment-rich glacial meltwater infuence salinity, water column turbidity, and light penetration with ecological implications on the microbial features. With the aim to address the temporal variability of the microbial assemblage in relation to environmental variables, a 7-day study was carried out in Kongsforden, in late sum- mer 2013. Abiotic (temperature, salinity, nutrients, total suspended matter, particulate inorganic, and organic carbon) and biotic (phyto -, picophyto-, bacterio-, and virioplankton abundance and microbial respiration) parameters were investigated at a station in the inner ford area, ca. 8.5 km away from the glacier front. Phyto-, picophyto-, and virioplankton showed low abundance. Dinofagellates and coccolithophorids dominated the phytoplankton community while Synechococcus sp. the picophytoplankton alone, in relation with Atlantic water. Low virus to bacteria ratios were detected, presumably linked to the high sedimentation rates. Interesting variability for picophytoplankton with depth, virioplankton with both time and depth, and respiratory rates with time were found. Moreover, the organic matter turnover was slower on the frst sampling day compared to that of the following days. Planktonic abundance depended on the variability of both hydrology (seawater mass infow) and freshwater runof from the glacier (relative turbidity degree). Diferently, the metabolic rates of respiration appeared to be linked with the particulate carbon pool. Over 1-week study, the diverse microbial dynamics appeared to be conditioned on complex forcing, emphasizing the importance of high-resolution experiment. Keywords Short-term dynamics · Phytoplankton · Bacterioplankton · Virioplankton · Microbial respiration · Kongsforden * M. Azzaro maurizio.azzaro@cnr.it 1 National Research Council, Institute of Polar Sciences, Spianata San Raineri, 98122 Messina, Italy 2 National Research Council, Institute of Marine Sciences, Forte Santa Teresa Pozzuolo Di Lerici, 19032 La Spezia, Italy 3 National Research Council, Institute of Water Researches, Via Roma, 74121 Taranto, Italy 4 National Research Council, Institute of Polar Sciences, Via Gobetti, 40129 Bologna, Italy 5 National Research Council, Institute for Biological Resources and Marine Biotechnologies, Spianata San Raineri, 98122 Messina, Italy 6 Federal University of Rio de Janeiro, Instituto de Microbiologia Paulo de Góes, Av. Carlos Chagas Filho, 373, Rio de Janeiro, Brazil 7 Federal University of Rio de Janeiro, Institute of Biology,, Av. Prof. Rodolpho Rocco 211, Rio de Janeiro, Brazil