Spatial variability in biomass and production of heterotrophic bacteria in the East China Sea and the Yellow Sea

The distributions of heterotrophic bacterial abundance and production were investigated in the East China Sea and the Yellow Sea during the autumn of 2000 and spring of 2001. Bacterial abundance varied in the range 3.2–15.7 (averaging 5.7) × 105 and 2.3–13.6 (averaging 6.2) × 105 cells cm−3 in the spring and autumn, respectively. During autumn, bacterial production (BP) (0.27–7.77 mg C m−3 day−1) was on average 3 fold that in spring (0.001–2.04 mg C m−3 day−1). Bacterial average turnover rate (ratio of bacterial production:bacterial biomass, μ=0.21 day−1) in autumn was 3 times as high as in spring (0.07 day−1). The ratio of integrated bacterial biomass to integrated phytoplankton biomass in the euphotic zone ranged from 4 to 101% (averaging 35%) in spring and 24 to 556% (averaging 121%) in autumn. The results indicate that the distributions of heterotrophic bacteria were controlled generally by temperature in spring and additionally by substrate supply in autumn.