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).