Fig. 5

Diversity Indices of all samples grouped by depth. a Richness is shown as the number of observed amplicon sequence variants (ASVs). Richness gives equal weight to all ASVs regardless of their abundance. b Shannon entropy considers ASV richness and proportional abundance, c Chao1 richness represents an estimate of the total number of ASVs that may be present in the sample. d Inverse Simpson diversity considers ASV richness and proportional abundance, similar to Shannon entropy, but gives additional weight to proportional abundance (evenness). All indices show significantly lower diversity in the bloom layers, especially at 25 cm depth, as compared to the top and bottom layers. Diversity indices were calculated using a subsampling approach to account for unequal sampling effort. Pairwise comparisons with low significance levels are shown (NS, *: p < 0.1, **: p < 0.01). All pairwise comparisons that are not shown were highly significant (***: p < 0.001), e.g. panel a 5 cm vs 10 cm