Fig. 3: Identity and relationships in the biofilm community before MCA removal.

a Relative abundance of the initial core community. Each bar represents the average of three biological replicates. Error bars represent standard deviations for the total relative abundance of this core community (n = 3 at each sampling location and time). The dashed, vertical line represents the end of chloramination. Note that the x-axis is not to scale: the final samples were taken 10 months after the penultimate samples. b Co-occurrence network showing nodes representing ASVs potentially involved in MCA metabolism. Shown is a component which included ASVs identified as core taxa, selected visually from the full co-occurrence network (Supplementary Fig. 3). Edges represent strong (Spearman’s rho > 0.75) and significant (Holm-adjusted p < 0.01) correlations in TCC scaled abundance. The nodes represent ASVs and are colored by class (red = Alphaproteobacteria, purple = Nitrospiria).