Table 2. Numbers of heterotrophic bacteria as determined by the heterotrophic plate count (HPC) method, expressed as percentages of the direct total bacterial count (TBC).

Day of voyage	HPCsw/TBC (%)			HPCfw/TBC (%)
	SW series	BW series		SW series	BW series
		Surface	Bottom		Surface	Bottom
1	1.57	0.24	0.40	0.07	0.01	0.03
2		0.33	0.28		0.01	0.01
3		0.33	0.66		0.01	0.05
4		0.81	4.16		0.02	0.15
5*	1.19	0.57	0.45	0.02	0.02	0.01
6		0.52	0.50		0.02	0.02
7		0.43	4.45		0.20	0.02
8		0.78	3.87		0.11	0.08
9		6.13	4.89		0.06	0.05
10		9.84	7.65		0.10	0.08

SW, seawater samples; BW, ballast-water samples. Asterisk (*) indicates mid-ocean ballast-water exchange on day 5. Heterotrophic bacterial counts are from both freshwater-based medium (HPC_fw) and seawater-based medium (HPC_sw).