Table 1. Environmental drivers of free-living and particle-attached communities.

Environmental variable	Particle-attached		Free-living
	Mantel r	P-value	Mantel r	P-value
Depth	0.145	0.11	0.261	0.06
Salinity	0.332	<0.01*	0.060	0.24
Potential temperature	0.156	0.01*	0.124	0.07
Apparent oxygen utilization	0.426	<0.01*	0.077	0.17
Prokaryotic heterotrophic activity	−0.156	0.93	−0.170	0.94
Prokaryote abundance	−0.156	0.90	−0.145	0.86
Percentage of HNA-content prokaryotes	−0.100	0.78	−0.077	0.67
Prokaryote biomass duplication time	0.209	0.01*	0.100	0.15
Prokaryote abundance (0–200 m)	−0.145	0.95	−0.059	0.67
Best BIOENV model	0.427 (AOU+DT)	<0.01*	0.280 (depth+potential temperature)	0.02*

Abbreviation: HNA, high nucleic acid. Mantel correlation (using Pearson correlation) between the Bray–Curtis dissimilarity and the Euclidean distance for particle-attached and free-living prokaryotes of the environmental variables used in the BIOENV approach (see Supplementary Information). Single variables and the best BIOENV model for each fraction are tested. Significant P-values (<0.05) are indicated with an asterisk.