Vertical and longitudinal gradients in HNA-LNA cell abundances and cytometric characteristics in the Mediterranean Sea

Type Article
Date 2011
Language English
Author(s) Van Wambeke France1, Catala P.2, 3, Pujo-Pay M.2, 3, Lebaron P.2, 3
Affiliation(s) 1 : Univ Aix Marseille 2, CNRS, Lab Microbiol Geochim & Ecol Marines, UMR6117, F-13288 Marseille 9, France.
2 : Univ Paris 06, Lab Arago, Observ Oceanol, F-66651 Banyuls Sur Mer, France.
3 : CNRS, LOMIC, Observ Oceanol, UMR7621, F-66651 Banyuls Sur Mer, France.
Source Biogeosciences (1726-4170) (Copernicus Gesellschaft Mbh), 2011 , Vol. 8 , N. 7 , P. 1853-1863
DOI 10.5194/bg-8-1853-2011
WOS© Times Cited 31
Abstract Heterotrophic bacterioplankton abundance and production were investigated with depth (down to bathypelagic layers) and with longitude (from 4.9 degrees E to 32.7 degrees E) along a cruise track across the Mediterranean Sea in early summer 2008. Abundances and flow cytometric characteristics (green fluorescence and side scatter signals) of high nucleic acid (HNA) and low nucleic acid (LNA) bacterial cells were determined using flow cytometry. Contrary to what is generally observed, the relative importance of HNA cells, as a percent of total cells, (%HNA, range 30-69%) was inversely related to bacterial production (range 0.15-44 ngC l(-1) h(-1)) although the negative relation was weak (log-log regression r(2) = 0.19). The %HNA as well as the mean side scatter of HNA group increased significantly with depth in the meso and bathypelagic layers. Vertical stratification played an important role in influencing the distribution and characteristics of bacterial cells especially with regard to layers located above, within or below the deep chlorophyll maximum. Within a given layer, the relationships between the flow cytometric characteristics and environmental variables such as chlorophyll-a, nutrients or bacterial production changed. Overall, the relationships between HNA and LNA cells and environmental parameters differed vertically more than longitudinally.
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