Distribution of viable marine bacteria in neritic seawater around Japan

Abstract

The direct viable count (DVC) method of determining the number of living bacteria in natural seawater was applied to samples collected from areas around Japan ranging from polluted to oligotrophic. In summer, the DVC comprised 1.5–39.8% (mean, 11.2%) of the total direct count (TDC) in Tokyo Bay, which was highly eutrophic. In offshore areas (Sagami Bay and the Kuroshio region), the percentages ranged from 0.7 to 7.9 (mean, 2.8%). In winter, slightly higher percentages were observed in Sagami Bay. The majority of DVC cells were free-living. The distribution of bacteria correlated closely with particulate or dissolved organic matter.