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).