Neighbor-joining tree of partial <i>nifH</i> amino acid sequences.

<p>The sequences recovered from transects 1 and 2 are depicted in bold font. The number of clones recovered for each sample is indicated in parenthesis, and the station (st) and depth where the sample was recovered are shown. Clusters according to <i>nifH</i>-based phylogeny are shown to the right of the tree. Phylotypes are labeled as N1-N14 and cross-referenced with accession numbers in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0143775#pone.0143775.s007" target="_blank">S2 Table</a> (note that sequence M6432A05 is not included in the tree due to it being shorter). Reference amino acid sequence names are shown with GenBank accession, site, depth and clone numbers (where available). The sequences M6433A04 (N4), M6411A02 (N6) and M6413A02 (N10) were used for qPCR assays.