Taxonomic, functional and phylogenetic turnover from eDNA
As regards to the β diversity, and considering the data set obtained by applying the ObiTools pipeline, the pairwise Jaccard’s dissimilarity index calculated between Willemstad and Valentijnsbaai reached a value of 0.395 meaning that the two areas present a moderate dissimilarity in species composition. The two areas had 49 taxa in common and did not share 32 among the 129 listed. The difference in taxa composition between the two regions was mainly explained by taxa turnover (βjtu = 0.379), while the value of the taxa nestedness is low (βjne = 0.016). Considering phylogenetic dissimilarity, the two areas presented a moderate level of dissimilarity (β UniFrac= 0.31), mainly explained by a turnover component (β UniFracTurn= 0.27; Figure 2c). The functional dissimilarities between the two areas were generally low (βFjac = 0.14), with a limited functional turnover (βFjtu = 0.077; Figure 2b). Applying an ordination on the MOTUs composition, we further found significant differences in composition between the two areas. The PCoA for eDNA explains a significant fraction of the total inertia (41%) with 22.5 % for the first axis and 18.5% for the second axis (Figure 3a and b) and showed a marked difference in composition between those two coastal areas. The difference was especially marked with the three samples from the North of the island. In contrast, the two samples south of the area were more similar with Willemstad. The partial overlap of the two areas was also highlighted with the UVC (Figure 3c and d). The PCoA for UVC explains a more limited fraction of the total inertia (25.9%) with 16.5 % for the first axis and 9.4% for the second axis (Figure 3c and d).