| Summary: | 2nd International Ocean Research Conference, One planet one ocean, 17-21 November 2014, Barcelona, Spain The Arctic Ocean is rapidly changing where increasing water temperatures and rapid loss of sea-ice will likely influence the structure and functioning of the entire ecosystem. The aim of this study was to synthesize the current state of knowledge on microbial abundances and processes from a Pan-Arctic perspective and attempt to predict how patterns may change under a warming scenario. To achieve this, we a) compared published available data for viral, bacterial and protist abundance, bacterial production (BP), respiration, grazing rates (GT) and viral lyses (VL) among different Arctic Regions, b) determined the temperature sensitivities of the afore mentioned processes, and c) tested which factors beyond temperature influenced these rates. Our results showed that 1) microbial abundances and rate processes are higher in the Eastern Arctic, 2) grazer control of bacteria is also stronger in the East (more direct transfer of bacterial carbon (C) to higher trophic levels), 3) bacterial loss by VL is proportionally more important in the West (greater recycling of bacterial C), and 4) there is a differential response to warming temperatures among processes. BP and GT responded similarly and more strongly to increases in temperature than VL did, suggesting a shift in dominant predator control for the Western region under a warming scenario. However, resource-related factors also exerted a strong influence in regulating these rates. Although generalized patterns could be elucidated, more information is needed to predict and understand how a changing Arctic will alter C pathways in the microbial food web among regions and over seasons Peer Reviewed
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