title: Latitudinal trends of Crenarchaeota and Bacteria in the meso- and bathypelagic water masses of the Eastern North Atlantic.
abstract: The distribution and activity of the bulk picoplankton community and, using microautoradiography combined with catalysed reported deposition fluorescence in situ hybridization (MICRO-CARD-FISH), of the major prokaryotic groups (Bacteria, marine Crenarchaeota Group I and marine Euryarchaeota Group II) were determined in the water masses of the subtropical North Atlantic. The bacterial contribution to total picoplankton abundance was fairly constant, comprising approximately 50% of DAPI-stainable cells. Marine Euryarchaeota Group II accounted always for < 5% of DAPI-stainable cells. The percentage of total picoplankton identified as marine Crenarchaeota Group I was approximately 5% in subsurface waters (100 m depth) and between 10% and 20% in the oxygen minimum layer (250-500 m) and deep waters [North East Atlantic Deep Water (NEADW) and Lower Deep Water (LDW), 2750-4800 m depth]. Single-cell activity, determined via a quantitative MICRO-CARD-FISH approach and taking only substrate-positive cells into account, ranged from 0.05 to 0.5 amol D-aspartic acid (Asp) cell(-1) day(-1) and 0.1-2 amol L-Asp cell(-1) day(-1), slightly decreasing with depth. In contrast, the D-Asp:L-Asp cell-specific uptake ratio increased with depth. By combining data reported previously using the same method as applied here and data reported here, we found a decreasing relative abundance of marine Crenarchaeota Group I throughout the meso- and bathypelagic water column from 65 degrees N to 5 degrees N in the eastern basin of the North Atlantic. Thus, the relative contribution of marine Crenarchaeota Group I to deep-water prokaryotic communities might be more variable than previous studies have suggested. This apparent variability in the contribution of marine Crenarchaeota Group I to total picoplankton abundance might be related to successions and ageing of deep-water masses in the large-scale meridional ocean circulation and possibly, the appearance of crenarchaeotal clusters other than the marine Crenarchaeota Group I in the (sub)tropical North Atlantic.
authors.affiliation: Department of Biological Oceanography, Royal Netherlands of Sea Research, 1790 AB Den Burg, The Netherlands.
authors.forename: Marta M
authors.initials: MM
authors.lastname: Varela
authors.forename: Hendrik M
authors.initials: HM
authors.lastname: van Aken
authors.forename: Eva
authors.initials: E
authors.lastname: Sintes
authors.forename: Gerhard J
authors.initials: GJ
authors.lastname: Herndl
mesh_terms: D001224:Aspartic Acid / Q000096:biosynthesis / Q000378:metabolism; D001267:Atlantic Ocean; D001419:Bacteria / Q000254:growth & development* / Q000378:metabolism; D019615:Crenarchaeota / Q000254:growth & development* / Q000378:metabolism; D026603:D-Aspartic Acid / Q000096:biosynthesis / Q000378:metabolism; D017753:Ecosystem; D019605:Euryarchaeota / Q000254:growth & development* / Q000378:metabolism; D005843:Geography; D017404:In Situ Hybridization, Fluorescence / Q000379:methods; D008852:Microradiography / Q000379:methods; D010100:Oxygen / Q000378:metabolism; D010933:Plankton / Q000254:growth & development; D054712:Salinity; D012623:Seawater / Q000382:microbiology*; D013696:Temperature; D014871:Water Microbiology
chemical_list: D001224:Aspartic Acid; D026603:D-Aspartic Acid; D010100:Oxygen