First study on microbial community-level physiological profiles across a subArctic Atlantic marine transect

In SubArctic ecosystems the microbial metabolic response to environmental changes is still underinvestigated. In the framework of the pan-Arctic Synoptic Arctic Survey network, the microbial community physiological profiles were determined by Biolog Ecoplates in a pelagic transect crossing the Greenland Sea at 75°N. At six hydrographic stations, seawater was sampled to cover the whole water column ranging from surface to 3532 m of depth. Spatially different metabolic pathways were found, with carbohydrates, carboxylic acids and amino acids preferentially metabolized within the photic zone (mean value 22.5, 22.3 and 18 % of the total, respectively), carbohydrates and carboxylic acids in the aphotic zone (26.40 and 24.17 %, respectively. High carbon substrate utilization rates were recorded in the middle of the transect. Community-level physiological profiles were not affected by abiotic parameters, except in the aphotic zone, where carbohydrate and carboxylic acid utilization correlated with temperature. Being the first dataset available in this subArctic area, the observed metabolic patterns hold remarkable ecological interest also in the light of future global warming scenarios, underlining the microbial physiological plasticity to utilize a diversified range of organic substrates in such an extremely dynamic environment.