3.2.3. Case study 3
The study of marine diplonemids diversity (Flegontova et al., 2016) revealed that they were stratified according to depth, with a large fraction of OTUs (35.6%) concentrated in the mesopelagic zone (Figure 4A, (Flegontova et al., 2016)). In Figure 4B of (Flegontova et al., 2016), a nMDS based on Bray-Curtis dissimilarities between samples supported the difference in diplonemid community composition and showed that the mesopelagic samples stood apart from the epipelagic samples (surface and DCM). Using the OBA “Community ecological analysis “ and querying the Tara Oceans 18S-V9 metabarcode dataset with the taxonomy ‘Diplonemida”, we were able to obtain similar results (Figure 6). A nMDS ordination with depth as the environmental variable (Figure 6A) illustrated how mesopelagic samples (green square) clustered mostly separately from the surface and DCM samples (blue boxes and red circles). The boxplot in Figure 6B identified mesopelagic samples as containing the highest Diplonemids diversity, both in terms of richness (number of OTUs; Figure 6B left panel) and Shannon index (Figure 6B right panel).