Table 1.

Relative importance of various factors in bacterial communities within each ecosystem, calculated by Adonis

	Explanatory factor for Adonis analysis			Number in analysis (filters)—samples
	Portion of variation accountable to  factor (p value)
Ecosystem	Sampling Site	Size	Site × size
Lake water	0.31 (0.001)	0.24 (0.001)	0.08 (0.628)	(32)—16
River water	0.14 (0.001)	0.37 (0.001)	0.08 (0.007)	(36)—18
Groundwater	0.38 (1.00)	0.38 (1.00)	0.24(1.00)	(8)—4
Wastewater	0.33 (0.001)	0.33 (0.001)	0.18 (0.065)	(12)—6
Tap water	0.51 (1.00)	0.31 (1.00)	0.18 (1.00)	(8)—4

For each explanatory variable (sampling site, size, and interactions between these two factors), the portion of variation accounted for by each variable and the p value for statistical significance of the variable are expressed. Sampling site refers to the specific location for each sample (i.e., River A vs. River B). For this analysis, only large and small bacteria groups were included for size (“All bacteria” was excluded from analysis). Large bacteria is the HNA-dominated community collected on a 0.4 µm filter, and Small bacteria is the LNA-dominated community in the 0.4 µm filtrate, collected on a 0.2 µm filter