Integrate biomasses (mg C m^-2) over the 0–75 m water column of Chl <i>a</i>, HP, picoeukaryotes, nanoeukaryotes, <i>Synechococcus</i>, and <i>Prochlorococcus</i> at Pt. B station in 2009 and 2010.

<p>Integrate biomasses (mg C m^-2) over the 0–75 m water column of Chl <i>a</i>, HP, picoeukaryotes, nanoeukaryotes, <i>Synechococcus</i>, and <i>Prochlorococcus</i> at Pt. B station in 2009 and 2010.</p

PCA variables factor map representing projection of variables on the plane defined by the first two principal components.

<p>The cycle of correlation represents the changes of the biological and biogeochemical parameters over time.</p

Principal Components Analysis (PCA) ACP-Plan 1/2, applied to data from 6 January 2009 to 28 December 2010.

<p>The 42-active data set consisted of 101 week values described by 42 biological variables: HP, <i>Synechococcus</i>, <i>Prochlorococcus</i>, picoeukaryotes, nanoeukaryotes abundances, fluorescence intensity and the Chl <i>a</i> concentration at 6 discrete depths (0, 10, 20, 30, 50, 75 m). Illustrative variables are concentrations of nutrients (NO₂^-, NO₃^-, PO₄^3-, Si(OH)₄, POC concentrations. In red the year 2009, in blue 2010. N = 7420. The blue zone in the figure corresponds to the seasonal variability between 2009 and 2010 highlight by the ACP.</p

Heterotrophic prokaryote (HP), HNA cells concentrations (10⁵cells cm⁻³) and ratio of HP to total photosynthetic carbon biomass (HP/PHYTO) at Pt. B station in 2009 (N = 306) and 2010 (N = 300).

<p>Heterotrophic prokaryote (HP), HNA cells concentrations (10⁵cells cm⁻³) and ratio of HP to total photosynthetic carbon biomass (HP/PHYTO) at Pt. B station in 2009 (N = 306) and 2010 (N = 300).</p

Distribution of the 18 PECs among the 4 trophic communities used in the text.

<p>Distribution of the 18 PECs among the 4 trophic communities used in the text.</p

18 Plankton Ecological Categories, PECs (abbreviations), symbols, and ecological traits.

<p>The symbols used as visual aid in the figures.</p

Variations of environmental conditions at the sampling station between December 2010 and October 2011.

<p>The two coloured bars at the top represent the duration of the different clusters based on the two sets of variables, <i>i</i>.<i>e</i>. physical (W = winter, SP = spring, T = transition, S1 = summer 1, S2 = summer 2) and biological (W = winter, ES = early spring, LS1 = late spring 1, LS2 = Late Spring 2, S = summer) (the clustering analyses are detailed in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0119219#pone.0119219.g004" target="_blank">Fig. 4</a>). Panels: (a) temperature, (b) salinity, (c) water density with (indicated below) periods of mixing (M1–M4) and stability (ST1-ST4), (d) nitrate, and (e) silicate. The white dotted curve repeated in all panels represents the depth of the maximum density gradient (pycnocline) estimated from the Brunt-Vaïsälä frequency. The vertical lines represent the limits of clusters based on biological variables (<i>i</i>.<i>e</i>. PEC time series).</p

Cluster analyses of physical (temperature and salinity, left) and biological (PEC biovolumes, right) data.

<p>Three significant clustering levels were identified for the physical characteristics of the water column: level P1, (cut-off = 11, red and blue branches of the tree); level P2 (cut-off = 8.6, solid-line coloured rectangles); level P3 (cut-off = 5.8, dashed-line coloured rectangles). Four significant clustering levels were identified for the biological data: level B1 (cut-off = 3.71, red and blue branches of the tree); level B2 (cut-off = 3.28, solid-line coloured rectangles); level B3 (cut-off = 2.89, dashed-line rectangles) which clustered 4 groups; level B4 (cut-off = 2.89, coloured fonts) which clustered 5 groups.</p

Time series of PEC biovolumes at the sampling station from December 2010 to October 2011.

<p>The top coloured bars represent the periods identified from the clustering analyses based on physical and biological variables (coloured bars as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0119219#pone.0119219.g003" target="_blank">Fig. 3</a>). The vertical dashed lines represent limits of clusters based on biological variables (<i>i</i>.<i>e</i>. PEC time series). Red dashes under the <i>x</i>-axes represent mixing events (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0119219#pone.0119219.g003" target="_blank">Fig. 3</a>). Note the different scales on the <i>y</i>-axes.</p

Dates of mixing events and stability periods.

<p>Dates of mixing events and stability periods.</p