Table 1. Contribution of metabolic hierarchical system level 1 to the dissimilarity of the hydrocarbon-impacted and non-hydrocarbon-impacted metagenomes.

	Avg. Abundance
Metabolic Processes	Hydrocarbon-Impacted	Non-Impacted	Diss/SD	Cum %
Cofactors, Vitamins, Prosthetic Groups, Pigments	0.1	0.19	2.24	11.43
Virulence, Disease and Defence	0.1	0.19	2.24	22.86
Phages, Prophages, Transposable elements, Plasmids	0.1	0.19	2.24	34.29
Fatty Acids, Lipids, and Isoprenoids	0.1	0.19	2.24	45.71
Iron acquisition and metabolism	0.84	0.79	1.63	52.68
Dormancy and Sporulation	0.71	0.68	1.49	57.48
Motility and Chemotaxis	0.83	0.81	1.58	61.17
Metabolism of Aromatic Compounds	0.87	0.85	1.73	64.81
Secondary Metabolism	0.76	0.75	1.16	68.32
Regulation and Cell signalling	0.86	0.83	1.86	71.55
Protein Metabolism	0.94	0.96	3.42	74.53
Carbohydrates	0.97	1	3.5	77.49
Nitrogen Metabolism	0.84	0.82	1.74	80.17
Photosynthesis	0.69	0.69	1.3	82.75
Amino Acids and Derivatives	0.96	0.98	2.89	85.24
Clustering-based subsystems	0.98	0.99	1.96	87.06
Miscellaneous	0.94	0.96	3.14	88.7

Hydrocarbon-impacted samples include a hydrocarbon-impacted foreshore and a biopile from Australia [40; Smith et al., unpublished data], and 2 biopiles from the Arctic region [40], while the non- impacted samples included 2 marine sediment samples from Australia and 3 sediment samples from the Coorong [50]. Average dissimilarity between the two groups is 1.78 % (Table S1 in File S1). Only metabolisms that were consistent (i.e. Diss/SD > 1.4) are shown here. The larger value in each case (i.e. the potential indicator of that condition) is shown in bold.

Cut-off percentage = 90% of the total dissimilarity, Diss=dissimilarity; SD=Standard Deviation; Cum %=cumulative percentage of contribution to overall dissimilarity, Avg. Abundance values are reported for square-root transformed data