Fig. 1. Comparison of bacterial composition and nitrogen-fixation potential of M. vaginatus cyanosphere communities with varying nutrient additions.
a NMDS ordination of community dissimilarity of M. vaginatus cyanospheres (excluding M. vaginatus itself) treated with nutrient additions (P-addition: n = 7, N-addition: n = 6) and untreated controls (n = 4), based on Bray–Curtis pairwise distances computed on the Hellinger-transformed sequence level composition with 95% confidence ellipses drawn for each, with a stress value of 0.13. Cyanosphere communities show significant differences among treatments and controls (PERMANOVA, P < 0.001). b Ratio of the nifH to 16S rRNA gene copy number in M. vaginatus cyanosphere communities in the same samples as in (a), showing significant differences between treatments (one-way ANOVA, P < 0.001), with control and P-addition treatment having significantly higher ratios than those in the N-addition treatment (Tukey, P < 0.002), but were not significantly different from each other (Tukey, P = 0.993).