南海SEATS站超微型浮游植物类群及其碳生物量和叶绿素a浓度比值的变化

(厦门大学 环境与生态学院,近海海洋环境科学国家重点实验室,福建省海陆界面生态环境重点实验室,福建 厦门 361102)

南海; 东南亚时间序列观测站; 超微型浮游植物; C:Chl-a

Variations of Pico-phytoplankton Groups and Carbon to Chlorophyll-a Ratios in the South China Sea at the SEATS Station
SHANG Yiwei,XIAO Wupeng,LIU Xin*,HUANG Bangqin

(State Key Laboratory of Marine Environmental Science,Fujian Provincial Key Laboratory for Coastal Ecology and Environmental Studies,College of the Environment & Ecology,Xiamen University,Xiamen 361102,China)

South China Sea; South East Asian Time-series Study station; pico-phytoplankton; C:Chl-a

DOI: 10.6043/j.issn.0438-0479.201805036

备注

浮游植物的碳生物量和叶绿素a浓度比值(简记为C:Chl-a)是海洋生物地球化学过程中的关键基础参数,在自然环境下有极大的变化.通过收集和整理近年来南海的东南亚时间序列观测(the South East Asian Time-series Study,SEATS)站的现场调查资料,对比分析了超微型浮游植物中三大类群的变化及其总C:Chl-a的垂直分布.叶绿素a浓度通过高效液相色谱分析获得,碳生物量依据文献报道的同纬度海区的C:Chl-a计算或基于流式细胞技术分析细胞丰度与体积后经换算得到.结果显示基于这两种方法计算得到的超微型浮游植物三大类群的碳生物量之间均存在极显著正相关(n=41,p<0.001),其中聚球藻(Synechococcus)基于高效液相色谱分析获得的碳生物量有一定的高估,而原绿球藻(Prochlorocoecus)和超微型真核藻类(pico-eukaryotes)的数据结果则基本一致,这种差异可能与聚球藻的光适应机制有关.通过计算南海SEATS站全粒径浮游植物的C:Chl-a,发现其呈现随深度递减的变化趋势,但相对于同纬度海区整体上偏小,进而讨论了南海SEATS站浮游植物时空分布模式和C:Chl-a变化的原因.

Carbon to chlorophyll-a(C:Chl-a)ratio is the most critical phytoplankton parameter in marine biogeochemical processes,but highly uncertain in the natural environment.Here,we took the South East Asian Time-series Study(SEATS)station located in the northern South China Sea basin with relatively stable environmental conditions as our study area.By compiling the observational data collected in recent years,we compared and analyzed the carbon biomass of three major pico-phytoplankton groups estimated from high performance liquid chromatography-chemical taxonomy(HPLC-CHEMTAX)analysis and flow cytometry(FCM)based cell abundances as well as cellular bio-volumes.The carbon biomass estimated from the two approaches all exhibited highly positive correlations of the three major picophytoplankton groups(n=41,p<0.001).According to the quantitative results,the carbon biomass of Synechococcus estimated by HPLC-CHEMTAX analysis has a certain overestimation,while the carbon biomass of Prochlorococcus and pico-eukaryotes are basically consistent with the results based on FCM.This may result from the light adaptation mechanism of Synechococcus.We calculated the phytoplankton total C:Chl-a in full size categories at SEATS in the South China Sea,and found that the C:Chl-a decreased with depth,and the overall value was relatively small compared with other marine ecosystems located at the same latitude.This paper systematically discussed the distributional pattern of phytoplankton community at the SEATSstation both spatially and temporally,and the likely reasons for the variations in C:Chl-a.