Figure 1.

Effect (mean±s.e.) of six bacterial strains on the relative abundance of active protists (Supplementary Figure S1) in three species (a–c) in volatile-mediated (red bars) and direct trophic (blue bars) interactions. Relative abundances were standardized (using Z-scores) per protist species and interaction type (direct vs VOCs) and centred on the control treatment for each species. Positive values indicate more active protists relative to cysts than in the control (that is, no bacterial volatiles or no bacteria in trophic interaction assays), negative values vice versa. Different letters indicate significant differences among bars tested per type of interaction (that is, letters a−c for volatile-mediated interactions, and q−t for direct trophic interactions). Asterisks indicate significant differences from the control, while dashed bars indicate a significant difference between volatile-mediated and direct trophic interactions. For raw data see Supplementary Figures S2 and S3; for statistical analyses Supplementary Tables S3-S5.