Distribution of virioplankton in the Jiaozhou Bay
胶州湾浮游病毒的分布研究

To study the distribution of virioplankton in the Jiaozhou Bay, three cruises were performed in June, July, and August 2007. Virioplankton abundance was determined by epifluorescence microscopy. Direct count of virus in the Jiaozhou Bay was ranging from 0.48×107 particles/mL to 22.78×107 particles/mL for all sample stations in three cruises, averaging 5.72×107±4.72 ×107 particles/mL. The abundance of virioplankton in July was significantly higher than those in June and August (P<0.01). Virioplankton abundance was higher in offshore waters, and decreased toward the open sea. There was no obvious pattern of vertical distribution of virioplankton. The Virus- to-Bacteria Ratio (VBR) ranged from 3.90 to 150.72, with an average of 42.05±28.55. According to multi-correlation analysis, virioplankton abundance was positively correlated with heterotrophic bacteria abundance (r= 0.605, P<0.01), Synechococcus abundance (r= 0.265, P<0.05) and Chlorophyll a concentration (r= 0.604, P<0.01). No significant correlations were found between virioplankton abundance and temperature and salinity. High VBR suggested a high portion of algal virus. VBR was negatively correlated with heterotrophic bacteria abundance (P<0.01), indicating relatively limited host species for phages.