04 A 942 Garneau TG

• Main Authors: Marie-Ève Garneau, Warwick F Vincent, Laura Alonso-Sáez, Yves Gratton, Connie Lovejoy, John Austin
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2006
• Subjects: Arctic; Arctic Ocean; Mackenzie River; Arctic Basin; Beaufort Sea; Mackenzie river
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1054.7258; http://www.cen.ulaval.ca/warwickvincent/PDFfiles/189.pdf

-1 ). Size-fractionation experiments at 2 coastal sites showed that > 65% of heterotrophic production was associated with particles > 3 µm. These results indicate the importance of particleattached prokaryotes, and imply a broad functional diversity of heterotrophic microbes that likely facilitates breakdown of the heterogeneous dissolved and particulate terrestrial materials discharged into arctic seas. KEY WORDS: Prokaryote diversity · Archaea · Proteobacteria · Cytophaga-FlavobacterBacteroides · Arctic Ocean · Mackenzie River estuary · Picocyanobacteria · CARD-FISH Resale or republication not permitted without written consent of the publisher Aquat Microb Ecol 42: [27][28][29][30][31][32][33][34][35][36][37][38][39][40] 2006 ments In the western Canadian Arctic, the Mackenzie River discharges large quantities of freshwater, solutes and sediments into a vast shelf region of the Beaufort Sea that extends >100 km offshore and encompasses a total area of 63 600 km 2 Macdonald et al. 1998) is the 4th highest in the Arctic Basin after the Siberian rivers Yenisei, Lena and Ob, with concomitantly large inputs of freshwater biota, terrestrial nutrients, organic carbon and suspended sediment. Each year, the river transports an estimated 118 to 127 × 10 6 t of sediments Our objective in the present study was to evaluate the offshore pattern in prokaryotic community composition and production of the Mackenzie River plume. We hypothesized that the freshwater influence would give rise to strong gradients in salinity, dissolved organic carbon (DOC) and particle loading that, in turn, would affect community structure and productivity. We addressed this hypothesis by way of a transect analysis during autumn conditions of minimum ice cover and moderate river flow. Microbial production was estimated with shipboard incubations of water samples with 3 H-leucine, and the offshore gradients in cell concentration of major taxonomic groups were determined by epifluorescence microscopy. Our approach included the application ...