List and parameters of stations sampled for bacterial community analysis.

*<p>positive temperatures in summer at surface, in winter at depth.</p

Depth profile of bacterial parameters in summer 2004 and winter 2006.

<p>Winter data are from 32 stations from 5 to 400 m; at 6 stations samples were also taken from 750 m. Summer: blue circles = ACC water; red circles = shelf water; green circles = mixed water; empty square = Winter. (Panel A) Bacterial abundance; (panel B) BCP = bacterial carbon production; BCP calculated from ³H-Leucine incorporation, employing a conversion factor of 3.1 kg C per mol of Leu <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0006941#pone.0006941-Simon1" target="_blank">[17]</a>; (panel C) μ = bacterial growth rate. Cell-specific growth rate calculations assumed 20 fg C per cell <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0006941#pone.0006941-Lee1" target="_blank">[18]</a>.</p

Areal data from summer 2004 and winter 2006 cruises.

<p>All parameters for the summer cruise have been integrated over the entire euphotic layer (1% incident PAR at surface; it was similar to the mixed layer depth or deeper). The winter PP has been integrated over the euphotic layer while other parameters have been integrated over the mixed layer depth (epipelagic) and from there down to 750 m (mesopelagic layer). Averages and standard deviation in parenthesis.</p><p>PP = primary production; BCP = bacterial carbon production; Summer excess DOC = summer dissolved organic carbon values minus average winter constant value (36.5±2.8 µM C s.d.); BCD = bacterial carbon demand (BCP/bacterial growth efficiency); N.D. = not determined.</p>*<p>BCD calculated using a bacterial growth efficiency derived by the curve in ref. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0006941#pone.0006941-Rivkin1" target="_blank">[20]</a> (∼36% in summer and 39% in winter).</p>**<p>BCD calculated using bacterial growth efficiency of 13% in summer and 6.2% in winter (averaging all data for summer and only HNLC for winter from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0006941#pone.0006941-Obernosterer1" target="_blank">[12]</a>).</p>§<p>no s.d. reported because the value is derived from a single depth profile.</p>°<p>DOC data for winter are not reported, since they are considered as constant refractory DOC values, and have been used to determine summer excess DOC.</p

List of GenBank accession number and closest relative to 16S rDNA bacterial sequences obtained from DGGE.

*<p>phylotypes found in both seasons. Ref. = References of the closest relative.</p

List of GenBank accession number and closest relative to 16S rDNA archaeal sequences obtained from DGGE.

*<p>phylotypes found in both seasons. Ref. = References of the closest relative.</p

DGGE fingerprint of <i>Archaea</i> amplicons from Summer 2004 (A) and Winter 2006 (B) samples.

<p>The numbered bands have been excised for sequencing.</p

DGGE fingerprint of <i>Bacteria</i> amplicons from Summer 2004 (A) and Winter 2006 (B) samples.

<p>The numbered bands have been excised for sequencing.</p

Sampling area and chlorophyll <i>a</i> distribution.

<p>(Panel A) MODIS-Aqua composite image of the chlorophyll-<i>a</i> gradient during 2004 summer. Red dots: summer 2004 sampling stations; white triangles: winter 2006 sampling stations. (Panel B) Depth profile of chlorophyll-<i>a</i> (<i>Chl a</i>) from summer 2004 cruise (blue circles = ACC water; green circles = mixed water; red circles = shelf water) and winter 2006 cruise (empty squares).</p

Depth profile of chemotrophic carbon production in winter 2006.

<p>DIC = dissolved inorganic carbon.</p

Depth distribution of organic matter pools during summer and winter cruises.

<p>Summer 2004: blue circles = ACC water; red circles = shelf water; green circles = mixed water; empty square = Winter 2006. (Panel A) DOC = Dissolved organic carbon. The data presented are measurements of total organic carbon, but since POC represents a negligible contribution to total organic carbon (POC represented only between 7% and 2% of the total pool) we can consider the analysis as DOC values. The shaded area covers the range of winter concentration. For a comparison, a range of variations of DOC from the FRUELA cruise study area in summer (Gerlache Strait, Bransfield Strait and Bellinghausen Strait) <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0006941#pone.0006941-Doval1" target="_blank">[22]</a> has been reported (black triangles). (Panel B) POC = Particulate organic carbon.</p