北部湾北部海域夏季浮游细菌空间分布特征及其影响因素

于2020年7月至8月在北部湾北部海域设立50个站位对浮游细菌和环境因子进行调查，探讨浮游细菌空间分布以及对环境因子的响应。研究结果显示：表层浮游细菌丰度变化范围为0.33～91.47×105cells/mL，平均值为12.61×105cells/mL；中层浮游细菌丰度变化范围为0.22～7.48×105cells/mL，平均值为2.15×105cells/mL；底层浮游细菌丰度的变化范围为1.76～71.33×105cells/mL，平均值为17.74×105cells/mL。浮游细菌丰度在水平方向上呈近岸沿海向远岸深海区域逐渐降低的趋势；垂直方向上浮游细菌丰度与深度相关性不显著（P>0.05），近岸海域浮游细菌丰度在垂直方向上没有明显的趋势，但远岸海域表层和中层丰度接近，底层丰度大于表层和中层的丰度。Pearson相关性分析显示，表层丰度与盐度、pH呈显著负相关（P<0.05），与硝酸盐、亚硝酸盐、硅酸盐呈极显著正相关（P<0.01）；中层丰度与温度、磷酸盐呈极显著正相关（P<0.01），与硝酸盐呈显著正相关（P<0.05）；底层与铵盐呈显著负相关（P<0.05），表明浮游细菌的空间分布受到温度、盐度、pH、营养盐等多个环境因子的共同影响。

Distribution characteristics of bacterioplankton in seawater of the northern Beibu Gulf and its environmental influence factors

From July 2020 to August 2020, 50 stations were set in the northern Beibu Gulf to investigate bacterioplankton and environmental factors, Spatial distribution of bacterioplankton and the correlation between bacterioplankton abundance and environmental factors were also alalyzed. The bacterioplankton abundance in surface layer ranged from 0.33×105 cells/mL to 91.47×105 cells/mL, with an average of 12.61×105 cells/mL; the abundance in middle layer ranged from 0.22×105 cells/mL to 7.48×105 cells/mL, with an average of 2.15×105 cells/mL; the abundance in bottom layer ranged from 1.76×105 cells/mL to 71.33×105 cells/mL, with an average of 17.74×105 cells/mL. The bacterioplankton abundance in the horizontal direction showed a decreasing trend from coastal areas to deep sea areas. There was no significant correlation between the bacterioplankton abundance and the depth in the vertical direction(P>0.05). There was no obvious vertical trend in the bacterioplankton abundance in the coastal waters, but the abundance in surface layer and middle layer in the in the offshore water were close, and the abundance in bottom layer was higher than that in surface layer and middle layer. Pearson correlation analysis showed that the abundance in surface layer had significantly negative correlations with salinity and pH ( P < 0.05 ), and very significantly positive correlations with nitrate, nitrite and silicate ( P < 0.01 ); the abundance in middle layer had very significantly positive correlations with temperature and phosphate ( P < 0.01 ), and significantly positive correlations with nitrate ( P < 0.05 ); the abundance in bottom layer had significantly negative correlation with ammonium ( P < 0.05 ), indicating that the spatial distribution of bacterioplankton was affected by multiple environmental factors such as temperature, salinity, pH and nutrients.