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

Abstract:

From July 2020 to August 2020, 50 stations were set up 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 analyzed.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 and in the offshore water was 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 had 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 had significantly positive correlations with nitrate (P<0.05); the abundance in bottom layer had significantly negative correlation with ammonium (P<0.05). This indicated that the spatial distribution of bacterioplankton was affected by multiple environmental factors such as temperature, salinity, pH and nutrients.