Table 2. Relationship between iron pathway prevalence, habitat and iron concentration across sites.

	Abb	Habitat effect Kruskal-Wallis p-value	Iron concentration effect Spearman Rho
			Coastal sites	Open ocean sites
Iron Pathway Prevalence
Flavodoxin Switch	FL	0.132	0.04	−0.45 *
Fe2+ uptake	F2	0.023	−0.33	−0.26
Fe3+ uptake	F3	0.005	−0.23	0.06
Heme uptake	HE	0.474	0.04	−0.57 **
Oxidative stress	OX	0.262	−0.32	−0.21
Regulation	RG	0.004	−0.29	0.02
Siderophore synthesis	SS	0.324	0.35	−0.26
Storage	ST	0.028	0.31	0.56 **
Siderophore uptake	SU	0.044	−0.14	−0.53 *
Unspecified iron transport	TR	0.003	−0.49 *	−0.31
Fisher combined p-value		***	*	***
Taxonomic prevalence
Actinobacteria	AB	0.951	0.34	−0.38
Bacteroidetes	BA	0.521	−0.19	0.20
Cyanobacteria	CY	9.10−5	0.11	0.13
Deinococcus-Thermus	DT	0.862	−0.12	0.22
Firmicutes	FI	0.12	0.24	0.26
Alpha-proteobacteria	aP	0.010	0.20	−0.06
Beta-Proteobacteria	bP	0.783	0.34	0.04
Delta-Proteobacteria	dP	0.630	−0.17	0.51 *
Epsilon-Proteobacteria	eP	0.025	−0.30	nd
Gamma-Proteobacteria	gP	0.015	0.05	−0.15
Spirochetes	SP	0.428	0.13	−0.003
Fisher combined p-value		***	ns	ns

*: p<0.05,

**: p<0.01,

***: p<0.001,

ns: not significant.