Table 1

Number of prokaryotes in aquatic habitats

HabitatVolume,* cm3Cells/ml, × 105Total no. of cells, × 1026
Marine
 Continental shelf2.03  ×  102051.0
 Open ocean
  Water, upper 200 m7.2  ×  10225360
  Water, below 200 m1.3  ×  10240.5650
  Sediment, 0–10 cm3.6  ×  10194600170
Fresh
 Lakes1.25  ×  1020101.3
 Rivers1.2  ×  1018100.012
Saline lakes1.04  ×  1020101.0
Total1180
  • * Marine, freshwater, and saline lake volumes were calculated from refs. 7 and 8