Abstract
Dissolved DNA (D-DNA) and Dissolved RNA (D-RNA) in seawater were measured in the productive layer (200m in depth) over a wide area of the North Pacific Ocean (from the central subarctic region to the central tropical region) including the Gulf of Alaska and the Bering Sea. The concentrations of D-DNA and D-RNA ranged from 0.5μg l-1 to 16μg l-1 and from 1.8μg l-1 to 25μg l-1 at all the stations, respectively. The ratio of RNA/DNA was within a range of 1-15 at all the stations. The concentrations of both D-DNA and D-RNA were higher in the upper water column (50m in depth) and lower in the lower water column (100-200m in depth) in respective regions. The concentration of D-DNA in the upper water column showed some regional variation; higher in the Bering Sea, and lower in the Gulf of Alaska and in the central tropical region. In contrast, the concentration of D-DNA in the lower water column did not show any regional variations. On the other hand, the concentration of D-RNA in the upper water column also showed some regional variations; higher in the Bering Sea and lower in the Gulf of Alaska. The spatial variation of D-DNA concentrations may be directly influenced by the biomass of bacteria. In contrast, the D-RNA concentrations may be directly influenced by the biological activity of bacteria in situ rather than by the biomass of bacteria.
