Figure 1

Sampling saturation of V9 tag libraries. Sampling saturation profiles of tag libraries generated for samples collected from anoxic waters of the Norwegian Framvaren Fjord (FV1-4) and the Caribbean Cariaco Basin (CAR1-4) at different levels of nucleotide differences for operational taxonomic units (OTUs). Only protistan and fungal tags were taken into account. Tags are clustered at k differences from k = 0 to 10 differences as described in pipeline 2 of the sequence data processing paragraph in the methods section. A difference can be an insertion or a mutation necessary to align the two sequences. At k differences, two tags having k or fewer differences are placed in the same cluster; if they have more than k differences, they are in two different clusters. Unique tags are tags clustered at 0 differences.