南黄海大型水母暴发区浮游生物群落代谢及细菌生产力

Metabolism of plankton community and bacterial production in jellyfish bloom area of southern Yellow Sea

于2013年6月(航段P1、P2)和2014年6月(航段P3、P4)上下旬4个航段,分别采用黑白瓶法和3H-亮氨酸示踪法测定南黄海大型水母沙海蜇(Nemopilema nomurai)暴发区的浮游生物群落代谢和细菌生产力(BP).结果表明,在水母暴发的航段中,细菌生产力和群落呼吸(CR)升高,净群落生产力(NCP)为负值.2013年6月,发现在水母生物量急剧增加的P2航段,细菌生产力显著升高,但细菌丰度(BA)变化不大,即单位细菌生产力显著上升,由1.75±0.87 pg/(cell·d)增加到3.31±1.22 pg/(cell·d)(p<0.05).2014年6月,水母暴发的P4航段中,细菌生产力没有显著上升,但群落总初级生产力(GPP)与群落呼吸的比值为0.46±0.25,显著低于P3航段的0.89±0.46(p<0.05);P_3、P_4净群落生产力分别为-0.84和-3.97 mmol/(m3·d),说明该区域水母暴发时呈异养状态;群落呼吸不完全由群落生产力所决定.由此可见,水母暴发可能促进单位细菌生产力增加,同时加强浮游生物群落的呼吸作用,对海洋生态系统中浮游生物群落代谢产生重要影响.

Metabolic state of plankton community and bacterial production （BP） were investigated in the southern Yellow Sea during bloom of giant jellyfish （Nemopilema nomurai） in June 2013 （section P1 and P2） and June 2014 （section P3 and P4）. The results showed that BP and community respiration （CR） increased, and net com- munity production （NCP） was negative during jellyfish bloom. In June 2013, although bacterial abundance （BA） was stable, BP significantly increased during jellyfish bloom （ section P2）, namely, cell-specific bacterial produc- tion significantly increased from 1.75 ± 0. 87 pg/（cell ·d） to 3.31 ± 1.22 pg/（cell · d） （p 〈 0. 05）. In June 2014, BP increased insignificantly on section P4, but the ratios of gross primary production （GPP） to CR de- creased significantly from section P3 （0.89 ± 0.46） to section P4 （0.46 ± 0. 25, p 〈 0.05 ）. Additionally, NCP was much lower on section P4 （ - 3.97 mmol/（ m3 · d） ） than on section P3 （ - 0. 84 mmol/（ m3 · d） ）. The negative NCP indicated that southern Yellow Sea waters were in the state of heterotrophic. CR was not entirely supported by the local primary productivity in the study areas. Our results suggest that jellyfish bloom possibly pro- mote BP and CR, and play an important role in plankton community metabolism.