3.4 Community structure along the pollution gradient
A comparison of alpha diversity indices revealed statistically significant differences between samples from skin and gut, as well as between sites (Table 1, Table S4). Significant interaction was detected between these two experimental factors. Seawater microbiota evidenced lower species richness and diversity, while the other three sources shared a similar richness and diversity regardless of sites (Figure S4). Overall, environmental samples from the highly polluted site (SFB) were higher in richness and diversity than the two other sites (Figure 4). For the moderately polluted site (LCC), a higher richness and diversity were observed in skin samples. Midgut microbiota is the richest and most diverse community in samples from the low polluted site (TPC).