Table 1. Composition of bacterioplankton in flow cytometrically sorted groups as relative abundance (% DAPI-stained cells) with oligonucleotide probes detailed in Supplementary Table 1.

Sample		LNA		Prochlorococcus
Latitude (°N)	Longitude (°W)	EUB I–III	SAR11-mix	EUB I–III	PRO405
34.21	29.72	ND	ND	93	88
32.43	31.8	ND	84	94	83
31.73	32.56	92	92	ND	82
28.11	36.51	93	98	95	90
23.77	41.11	88	97	93	86
21.21	39.29	90	96	94	86
16.19	35.8	88	98	94	85
13.47	33.95	90	96	97	95
7.82	30.16	80	89	94	93
4.8	28.16	84	84	93	93
	Mean±s.d.	88±4	93±6	94±1	88±4

Abbreviations: DAPI, 4,6-diamidino-2-phenylindole; EUB I-III, Bacteria; LNA, low nucleic acid; ND, not determined.