Fig. 4

Correlation between the concentration of metals and relative abundance of bacterial taxa. The size of the nodes is proportional to the relative abundance of the taxon, while the color indicates the strength of the association measured by the Spearman rho correlation coefficient. Only taxa that were present in more than 50% of the samples are shown. The labels for the taxa with the 25 strongest association (either positive are negative) are shown. The size of the nodes is proportional to the relative abundance of each taxon, while the color indicates the strength of the association measured by the Spearman ρ. The concentration of metals has a strong influence on bacterial taxa already at high taxonomic level. In particular, the relative abundance of Bacteria vs Archaea is strongly correlated with the concentration of Cu