Relative amounts of members of the Roseobacter clade (ROS), the Cytophaga-Flavobacterium cluster (CF), and the γ-Proteobacteria (GAM) in oxic and anoxic enrichments (24 h). Alt, Alteromonas; Psa, Pseudoalteromonas-Colwellia; Vib, Vibrio; others, other γ-Proteobacteria.