Fig. 3.

Relative abundance of major (A) bacteria and (B) archaea detected from the different water masses at phylum/class level. ‘Other phyla’ or ‘Other genera’ are bacterial phylum or archaeal genera with overall mean relative abundances of <0.5% across all water masses. ‘Unclassified archaea’ include archaeal zOTUs that were classified with bootstrap confidence values <50%. For each water mass type, samples are arranged by decreasing latitude from left to right, first for the Pacific and followed by Indian sector samples. Water column depth categories: Bathy‐Abyssopelagic (>1000 m), Mesopelagic (200–1000 m), and Epipelagic (<200 m) provide a rough depth indication of the different water masses. Full charts showing each of the 223 samples on the x‐axis are in Fig. S6. Water mass name acronyms are as indicated in Figs. 1 and 2 legends.