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In this dissertation, the author used flow cytometry to study the spatial and temporal distribution pattern of Cyanobacterium Synechococcus,picoeukaryotes, heterotrophic bacteria in South Yellow Sea and East China Sea. The author also studied the distribution of virioplankton in Jiaozhou Bay with epifluorescence microscopy. With the data got, the author hope to accumulate basic information regarding marine microbiol study for future research as well as to provide scientific reference for ecological protection measurements.1.Established the relationship between FSC signal of flow cytometry and cell diameter. With this relationship,researchers could get a better understanding of the marine picoplankton biomass in future studies.2.During the 7 cruises in South Yellow Sea, the Synechococcus average abundance and biomass was 4.0-54.2×103 cell/ml and 0.29-5.76μgC/L. For picoeukatyotes and heterotrophic bacteria, the average abundance and biomass was 1.4-8.0×103 cell/ml and 0.30-1.64μgC/L,4.1-8.9×105cell/ml and 8.11-17.69μgC/L, respectively. Synechococcus and heterotrophic bacteria had a same seasonal variation pattern, with highest value found in late spring to autumn, and the lowest value in winter and early spring. Picoeukaryotes had high abundance and biomass in spring, and during the rest season of the year, the abundance and biomass was relatively low. A positive correlation between water temperature and Synechococcus, heterotrophic bacteria biomass was found. In Yellow Sea Cold Water Mass, picoplankton had low abundance and biomass.3.The author reported the picoplankton variation during spring bloom in Yellow Sea. In all the 4 bloom studied, heterotrophic bacteria showed a same variation pattern, with a positive correlation with water chlorophyll a concentration.For Synechococcus and picoeukaryotes,the variation had two different trends.During the process of spring bloom, their biomass could either increase or decrease. There were several possible causes for the biomass decrease, which need further study in the future: different preponderant bloom phytoplankton species, light and nutrient competition with large phytoplarikton, and the lysis of virioplankton.4. In Jiaozhou Bay from 2006 to 2009,the Synechococcus surface average biomass ranged from 257 cell/ml to 263.9×103 cell/ml, with a seasonal variation of spring<winter<autumn<summer. The heterotrophic bacteria surface average biomass ranged from 1.07×104 cell/ml to 86.59×105 cell/ml, with a seasonal variation of winter<autumn<spring<summer. Synechococcus and heterotrophic bacteria abundance showed positive correlation with water temperature. Besides, heterotrophic bacteria abundance also showed positive correlation with water chlorophyll a concentration. This is the first report about virioplankton abunadance and distribution in Jiaozhou Bay. Result showed that the virioplankton abunadance varied from 0.48×107/ml to 22.78×107/ml, with positive correlation with Synehococcus and heterotrophic bacteria abundance, as well as water chlorophyll a concentration.5.In Changjiang Estuary and adjacent area, Synechococcus, picoeukaryotes and heterotrohic bacteria abundance ranged from 18.73-41.25×103 cell/ml,1.07-6.47×103 cell/ml, and 3.03-20.30×105cell/ml,respectively, from summer to autumn. Result showed that Synechococcus abundance was influenced by water temperature and nutrients, while the heterotrophic bacteria abundance was influenced by chlorophyll a and nutrients.In August 2006, when hypoxia was found outside Changjiang estuary, no apparent influence was found with water DO to Synechococcus,picoeukaryotes abundance. Heterotrophic bacteria abundance didn’t change significantly in hypoxia zone, either.
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