The Spatial And Temporal Distribution Of Virioplankton In The Jiaozhou Bay

In this paper, virioplankton in the Jiaozhou Bay in four seasons was detected byflow cytometry. The distribution characteristic of virioplankton abundance inhorizontal direction, vertical direction, in seasonal aspect and in circadian aspect wasstudied, and the distribution characteristic of its main host heterotrophic bacteria wasalso detected synchronously. And the correlation of virioplankton abundance andheterotrophic bacteria abundance, and environmental factors was analyzed. The resultof this study contributed to an overall understanding of the biological communitystructure in the Jiaozhou Bay, and provided basic data for the ecological environmentevaluation and monitoring of the waters.Result showed that the virioplankton abundance was4.30×10⁵～1.71×10⁷particles ml^-1and5.17×10⁶particles ml^-1on average. In horizontal direction,virioplankton abundance was higher in the inshore waters, while it was lower incentral waters. In vertical direction, virioplankton abundance on surface and on10meter layer was5.68×10⁶particles ml^-1and4.73×10⁶particles ml^-1on averagerespectively in spring, and9.25×10⁶particles ml^-1and4.00×10⁶particles ml^-1onaverage respectively in summer, and1.74×10⁶particles ml^-1and1.08×10⁶particlesml^-1on average respectively in fall, and4.01×10⁶particles ml^-1and3.32×10⁶particles ml^-1on average respectively in winter. There were no distinct variation ineach water layer in four seasons（Pï¹¥0.05）.The virioplankton abundance ranged from2.13×10⁶to1.48×10⁷particles ml^-1,5.44×10⁶particles ml^-1on average in spring. It ranged from1.01×10⁶to1.71×10⁷particles ml^-1,7.94×10⁶particles ml^-1on average in summer. It ranged from4.30×10⁵to8.53×10⁶particles ml^-1,1.58×10⁶particles ml^-1on average in fall. It ranged from1.86×10⁶to8.58×10⁶particles ml^-1,3.84×10⁶particles ml^-1on average in winter. Seasonalvariation of the virioplankton abundance：summer and spring＞winter＞autumn. The virioplankton abundance showed obvious difference between summer and winter （P﹤0.01）, and the abundance of virus showed very obvious difference between fall andother seasons （P﹤0.001）. The abundance of virus did not show obvious differencebetween spring and summer, spring and winter（Pï¹¥0.05）.The result of24hours of simultaneous observations of five continuous sitesshowed that the virioplankton abundanc of site A1、B3、C4and D5was on the risefrom13:30to19:30period. While site C2which was near the constructing JiaozhouBay Bridge, the virioplankton abundanc was very low and the circadian fluctuation ofvirus abundance variation was not obvious. The result of the circadian variation ofthree layers of D5site showed that the circadian fluctuations of virus abundancevariation were obvious at all water layers, and the fluctuations in trend were basicallythe same. But the circadian fluctuations amplitude of virus abundance on surface wasobvious, and that on10m layer and on bottom was flat.Result showed that the heterotrophic bacteria abundance was1.27×10⁵².55×10⁶particles ml^-1and7.26×10⁵particles ml^-1on average. In horizontal direction,heterotrophic bacteria abundance was higher in the inshore waters, while it was lowerin central waters. In vertical direction, heterotrophic bacteria abundance on surfaceand on10meter layer was1.18×10⁶and3.69×10⁵ml^-1particles ml^-1on averagerespectively in spring, and9.06×10⁵and1.17×10⁶particles ml^-1on averagerespectively in summer, and9.97×10⁵and5.39×10⁵particles ml^-1on averagerespectively in fall, and2.16×10⁵and1.95×10⁵particles ml^-1on averagerespectively in winter. There were no distinct variation in each water layer in fourseasons（Pï¹¥0.05）.The heterotrophic bacteria abundance ranged from2.81×10⁵to2.29×10⁶particlesml^-1,8.18×10⁵particles ml^-1on average in spring. It ranged from5.47×10⁵to1.91×10⁶particles ml^-1,9.70×10⁵particles ml^-1on average in summer. It ranged from3.25×10⁵to1.66×10⁶particles ml^-1,8.83×10⁵particles ml^-1on average in fall. It rangedfrom1.27×10⁵to5.64×10⁵particles ml^-1,2.10×10⁵particles ml^-1on average inwinter. The heterotrophic bacteria abundance showed obvious difference between winter and other seasons（P﹤0.001）, while that did not show obvious differenceamong spring, summer and autumn（Pï¹¥0.05）.The result of24hours of simultaneous observations of five continuous sitesshowed that the heterotrophic bacteria abundanc of site A1、B3、C4and D5was on therise from17:30to1:30period. While the heterotrophic bacteria abundanc of site C2was very low and the circadian fluctuation of heterotrophic bacteria abundancevariation was not obvious. The result of the circadian variation of three layers of D5site showed that the circadian fluctuations of heterotrophic bacteria abundancevariation were obvious at all water layers, and the fluctuations in trend were basicallythe same. But the circadian fluctuations amplitude of heterotrophic bacteriaabundance on surface was more obvious than that on10m layer and on bottom.VBR ranged from1.03to29.83and8.66on average in spring. It ranged from1.08to23.58and9.22on average in summer. It ranged from1.01to8.34and1.86onaverage in fall. It ranged from3.90to44.36and20.63on average in winter. VBRshowed obvious difference between winter and other seasons（P﹤0.001）, while it didnot show obvious difference among spring, summer and autumn（Pï¹¥0.05）.The correlations between virioplankton abundance and heterotrophic bacteriaabundance, picophytoplankton abundance（not published data of the lab）, VBR andenvironmental factors were as follows：in spring, virioplankton abundance waspositively related to VBR and the heterotrophic bacteria abundance; in summer,virioplankton abundance was positively related to VBR, temperature and nitrate, andnegatively related to water depth; in fall, virioplankton abundance was positivelyrelated to VBR and Euk, and negatively related to salinity; in winter, virioplanktonabundance was positively related to VBR, nitrate, nitrite and ammonium salt, andnegatively related to Syn, temperature and salinity.