Fig. 1.

(a) Relative abundance of major bacterial and archaeal phyla in the 16 S rRNA iTag dataset. The data are from all 10 depths sampled across the 2-year period. Only phyla with overall relative abundance > 2% are shown. Note the increasing relative abundance of Thaumarchaeota with depth. (b) Principal Component Analysis (PCA) plot showing the spread of samples along a depth gradient (PC1), based on measured environmental variables. Shapes correspond to the two stations, and vectors are drawn to highlight significant environmental variables explaining the variation along PC1 and PC2. Percent variability explained by each component is given in brackets next to the axis labels