Spatial variability of particle-attached and free-living bacterial diversity in surface waters from the Mackenzie River to the Beaufort Sea (Canadian Arctic)

• Published in: Biogeosciences
• Main Authors: Ortega-Retuerta, E., Joux, Fabien, Jeffrey, W.H., Ghiglione, J. F.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: European Geosciences Union 2013
• Subjects: Arctic; Arctic Ocean; Mackenzie River; Beaufort Sea; Ice; Mackenzie river; permafrost
• Online Access: http://hdl.handle.net/10261/115546; https://doi.org/10.5194/bg-10-2747-2013

Special issue How changes in ice cover, permafrost and UV radiation impact on biodiversity and biogeochemical fluxes in the Arctic Ocean – The Malina project.-- 13 pages, 6 figures, 4 tables, supplementary material related to this article is available online at: http://www.biogeosciences.net/10/2747/2013/bg-10-2747-2013-supplement.pdf We explored the patterns of total and active bacterial community structure in a gradient covering surface waters from the Mackenzie River to the coastal Beaufort Sea in the Canadian Arctic Ocean, with a particular focus on free-living (FL) vs. particle-attached (PA) communities. Capillary electrophoresis-single-strand conformation polymorphism (CE-SSCP) showed significant differences when comparing river, coast and open sea bacterial community structures. In contrast to the river and coastal waters, total (16S rDNA-based) and active (16S rRNA-based) communities in the open sea samples were not significantly different, suggesting that most present bacterial groups were equally active in this area. Additionally, we observed significant differences between PA and FL bacterial community structure in the open sea, but similar structure in the two fractions for coastal and river samples. Direct multivariate statistical analyses showed that total community structure was mainly driven by salinity (a proxy of dissolved organic carbon and chromophoric dissolved organic matter), suspended particles, amino acids and chlorophyll a. Pyrosequencing of 16S rRNA genes from selected samples confirmed significant differences between river, coastal and sea samples. The PA fraction was only different (15.7 % similarity) from the FL one in the open sea sample. Furthermore, PA samples generally showed higher diversity (Shannon, Simpson and Chao indices) than FL samples. At the class level, Opitutae was most abundant in the PA fraction of the sea sample, followed by Flavobacteria and Gammaproteobacteria, while the FL sea sample was dominated by Alphaproteobacteria. Finally, for the coast and river ...