Table 4. Summary of ordination analysis. RDA and CCA were performed for each and all of the 3 factors (site, type of substrate material, attachment position on the platform) to determine the explained variance in microbial community composition at the phylum and genus levels, respectively. Only the first and second axes were shown. P-value was calculated based on Monte Carlo test for all canonical axes.

Phylum level
	Site only		Material only		Position only		All
Axes	1	2	1	2	1	2	1	2
Eigenvalues	0.778	0.140	0.035	0.006	0.008	0.907	0.800	0.018
Cumulative percentage variance
of species data	77.8	91.8	3.5	4.0	0.8	91.5	80.0	81.8
of species-environment relations	100.0	0.0	85.5	100.0	100.0	0.0	96.8	98.8
Sum of all canonical eigenvalues	0.778		0.040		0.008		0.827
P-value	0.004		0.884		0.902		0.010