Table 4. Mean and s.d. values of the VBR (2000–2009), VPR (2002–2009), virus-to-Synechococcus ratio (2002–2009), virus-to-SAR11 ratio (2003–2005) and virus-to-Rhodobacteracea ratio (2003–2005) for mean values between 60 and 100 m for all data, and for subsets where the MLD <50 m and MLD >50 m.

All data points		MLD <50m		MLD >50 m
January–December		May–November		December–April
Mean	s.d.	Mean	s.d.	Mean	s.d.
VBR
9.2	3.5	9.1	2.7	9.5	4.3
n=129		n=65		n=64
VPR
120.8	120.9	69.8	24.3	157.5	139.0
n=95		n=45		n=50
Virus: synechococcus
897.3	1025.7	1065.2	881.6	800.9	1157.1
n=97		n=47		n=50
Virus: SAR11
31.0	14.0	29.8	10.0	32.9	16.8
n=42		n=19		n=23
Virus: Rhodobacteracea
270.3	239.2	193.5	106.4	318.7	292.8
n=42		n=19		n=23

Abbreviations: MLD, mixed layer depth; VBR, virus-to-bacterium ratio; VPR, virus-to-Prochlorococcus ratio.