FIG 3 .

Heatmap of viral richness at the family level per sample. Heatmap colors denote relative abundances per sample. Contigs larger than 300 nucleotides (nt) were assigned to a family or grouping by MEGAN6 using a lowest-common-ancestor algorithm, based on blastx-based homology using the program Diamond with the RefSeq viral protein database (version January 2017) and the nonredundant protein database (May 2017 version). Only those families/groups comprising large contigs (>1,000 nt) or with contigs mapping to viral signature genes (e.g., capsid and RNA-dependent RNA polymerase genes) were retained. LI, sewage influent; LE, sewage effluent; SW, estuarine surface water; Sed, estuarine sediment.