Seasonal Changes in Substrate Utilization Patterns by Bacterioplankton in the Amundsen Gulf (Western Arctic)

IPY2012 Conference Montréal. From Knowledge to Action, 22-27 April 2012, Montréal, CanadaDuring the Circumpolar Flaw Lead (CFL) System Study, 17 stations were sampled in the Amundsen Gulf (Western Arctic), a very dynamic area with heterogeneous ice conditions. In order to track metabolic diversity of heterotrophic bacterioplankton, Biolog MT2 MicroPlates® amended with custom selected substrates were inoculated with seawater from ice-covered to icefree conditions. Samples were taken from February to July 2008 at the surface (0-12 m) and intermediate depths (20-70 m). In winter, when concentrations of nutrients and chlorophyll a were extremely low, the number of substrates used was close to zero. In early spring, when the levels of chlorophyll a increased, so did the number of substrates used. This was followed by a onemonth period with no substrates used in April and May. Finally, the activity recovered towards the summer. The group of substrates most commonly used at all depths was carbohydrates, specially glucose and cellobiose. Amino acids were occasionally used both in surface waters and at intermediate depths. L-threonine was the most commonly used amino acid, together with Larginine and L-lysine at the surface and L-leucine at intermediate depths. These results were compared to those of a previous study in Franklin Bay, a relatively close area but with a different ice regime, showing a stable layer of land-fast ice throughout the period of study. The differences found in the metabolic capabilities between the two studies were likely a consequence of the different hydrographyPeer Reviewe

Seasonal changes in substrate utilization patterns by bacterioplankton in the Amundsen Gulf (western Arctic)

9 pages, 4 figures, 2 tablesDue to logistic difficulties, biological processes along the Arctic winter remain poorly known. In particular, carbon sources used by bacterioplankton have not been identified. A previous study in Franklin Bay suggested that polymers were one of the main substrates used by bacteria. During the Circumpolar Flaw Lead System Study, we analyzed metabolic capabilities of the heterotrophic bacterioplankton using Biolog MT2 MicroPlates® amended with custom-selected substrates. Our purpose was to test whether the use of polymers was a peculiarity of Franklin Bay or a robust feature of the Arctic winter community. Seventeen stations were sampled in the Amundsen Gulf (western Arctic), a very dynamic area with heterogeneous ice conditions, from February to July 2008, at the surface (0-12 m), intermediate depths (20-70 m), and near the bottom (200 m). In winter, when nutrients and chlorophyll a concentrations were low, the number of substrates used was close to zero. In early spring, when the levels of chlorophyll a increased, so did the number of substrates used. This was followed by a 1-month period with no substrates used in April and May. Finally, the activity recovered toward the summer. Amino acids were occasionally used. However, the group of substrates most commonly used at all depths was carbohydrates, especially cellobiose, maltose, N-acetyl-d-glucosamine and glycogen. All these are either polymers or monomers derived from polymers. These results confirm that the heterotrophic bacterial assemblage relies heavily on polysaccharides for subsistence during the Arctic winter. © 2014 Springer-Verlag Berlin HeidelbergThis work is a contribution to the International Polar Year-Circumpolar Flaw Lead System Study (IPY-CFL 2008) supported through grants from the Canadian IPY Federal Program Office and the National Sciences and Engineering Research Council. The Spanish participation was funded by the Spanish Ministry of Science and Innovation grants BOREAL (CGL2007-28872-E/ANT) and Marine Gems (CTM2010-20361) to C. P.-APeer Reviewe