Figure 4

Relative abundance of increasing bacterial (A) and fungal (B) indicator taxa (summed at the class and sub-division levels for bacteria and fungi, respectively) determined using TITAN2 along the gradient of oil contamination for the combination of both ETV and GUN sites. ETV and GUN sites are symbolised by pentagon and triangle symbols, respectively, and distance to the oil seep is shown with colour gradient (from red to green). At the OTU level, 281 and 61 bacterial and fungal indicator taxa were sorted with purity and reliability parameters both > 0.95. For the complete list of bacterial and fungal OTU found as indicator taxa see Table S2 and S3, respectively. The relative abundances of OTU belonging to similar classes were summed. The group “Others” comprise classes having less than 3 representative OTUs and were affiliated to Chlamydiae, Melainanabacteria (Cyanobacteria phylum), Dadabacteriia, Babeliae (Dependentiae phylum), Gemmatimonadetes, Latescibacteria, Nitrospira, Saccharimonadia (Patescibacteria phylum) and Rokubacteria NC10 classe. The group “other_Acidobacteria” comprise OTU affiliated to Holophagae, subgroup_5 and subgroup_22 classes. The group “other_Actinobacteria” comprise OTU affiliated to Thermoleophilia and Coriobacteriia classes. The group “other_Chloroflexi” comprise OTU affiliated to Chloroflexia, TK10 and JG30-KF-CM66 classes. The group “other_Firmicutes” comprise OTU affiliated to Bacilli and BRH-c20a classes.