Spatial Distributions of Picoplankton and Viruses in the Changjiang Estuary and Its Adjacent Sea Area during Summer

摘要

Simultaneous determination of picoplankton (i.e.,Synechococcusspp.,Prochlorococcusspp., picoeukaryotes, and heterotrophic bacteria) and viruses in the Changjiang (Yangtze) River estuary and its adjacent sea area was made using flow cytometry during a cruise in June 2006. The results show thatProchlorococcusin all samples was below detectable level. The abundances ofSynechococcus, picoeukaryotes, heterotrophic bacteria, and viruses ranged from0.00to1.22×108cell L−1,0.01×106to1.42×107cells L−1,8.40×107to4.29×109cells L−1, and1.20×107to1.06×1010particles L−1, respectively. The determined picoplankton groups and viruses distinctly increased with the distance off the estuary and where the maximum abundance that occurred in these groups was different somewhat due to the individual sensitivity to environmental changes. Viral abundance showed a positive correlation with salinity and negative correlations with turbidity and inorganic nutrient concentrations. Positive linear relations were found betweenSynechococcus, heterotrophic bacteria, and viruses.