Fig. 2

Ca. Chlorobium antarcticum abundance distribution in the Vestfold Hills. The stacked bar chart shows the relative abundance of Ca. Chlorobium antarcticum in the oxic-anoxic interface of Ace Lake (AL), Ellis Fjord (EF), and Taynaya Bay (TB). The AL abundances were generated from a time-series of metagenomes from different seasons (x-axis: Dec summer, red font; Jul and Aug winter, blue font; Oct and Nov spring, green font), whereas the EF and TB abundances were from metagenomes from spring (EF, Oct 2014; TB, Nov 2014) (Additional file 1: Table S1). The AL and EF data were from samples collected on large format filters (y-axis: 3 μm, red; 0.8 μm, yellow; 0.1 μm, purple), whereas the TB data were from samples collected using Sterivex cartridges (y-axis: 0.22 μm, blue). Due to the dynamic range of the data (0.4–84%), the percentage abundance values for Ca. Chlorobium antarcticum in metagenomes from each filter fraction and time period (see relative abundance calculation in the “Methods” section) are shown below the bar chart. Filter fractions: 0.22, 0.22–20 μm; 0.1, 0.1–0.8 μm; 0.8, 0.8–3 μm; 3, 3–20 μm