Latitudinal trends of Crenarchaeota and Bacteria in the meso- and bathypelagic water masses of the Eastern North Atlantic

• Published in: Environmental Microbiology
• Main Authors: Varela, M.M. (Marta María), Van-Aken, H.M. (Hendrik M.), Sintes, E. (Eva), Herndl, G.J. (Gerhard J.)
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Centro Oceanográfico de A Coruña 2008
• Subjects: North Atlantic; North East Atlantic; Northeast Atlantic
• Online Access: http://hdl.handle.net/10508/7637; https://doi.org/10.1111/j.1462-2920.2007.01437.x

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 ∼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 ∼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°N to 5°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. 6