南海东北部分粒级叶绿素a和超微型光合生物的周日变化  

Diel variations of size-fractionated chlorophyll a and picophytoplankton in the northeastern South China Sea

作　　者：姜歆[1,2,3] 黄良民 谭烨辉[1,2] 李佳俊 柯志新[1,2] 赵春宇 

机构地区：[1]中国科学院南海海洋研究所中国科学院热带海洋生物资源与生态重点实验室,广东广州510301 [2]广东省应用海洋生物学重点实验室,广东广州510301 [3]中国科学院大学,北京100049

出　　处：《海洋通报》2017年第6期689-699,共11页Marine Science Bulletin

基　　金：中国科学院海洋专项(XDA11020305);国家自然科学基金(41130855)

摘　　要：分别于2014年春、秋和2015年夏3个季节对南海东北部A站位(118°E,21.5°N)分粒级叶绿素a浓度和超微型光合生物(原绿球藻、聚球藻和超微型真核藻类)细胞丰度的昼夜变化进行了24 h时间序列连续观测和分析。通过萃取荧光法分析叶绿素a浓度,发现叶绿素a浓度呈现明显的昼夜变化,春季正午最高,秋季和夏季基本变化趋势为白天升高,夜晚降低;而因夏季中午的光抑制作用,叶绿素a的浓度相对较低。超微型光合生物(0.2~3μm)对总叶绿素a的贡献最高(>71.49%),小型浮游植物(>20μm)贡献率最低(<10.41%)。通过流式细胞技术检测到3个超微型光合生物类群;其中,原绿球藻为优势类群,最大细胞丰度达1.05×10~5cells/m L,其次是聚球藻,超微型真核藻类的细胞丰度最低,但由于其单位细胞内的叶绿素a含量高,所以可能对叶绿素a的贡献最大。聚球藻丰度基本上白天下降,傍晚到午夜上升;秋季和夏季,超微型真核藻类的丰度白天高,夜晚低,而春季则相反;原绿球藻在秋季和春季的昼夜变化规律和超微型真核藻类相似。在多种因素共同影响下,光照是调控叶绿素a浓度和超微型光合生物丰度昼夜变化的一个关键因素。季节变化上,原绿球藻的细胞丰度季节间没有统计学差异(P>0.05),聚球藻的季节变化为秋>夏>春,超微型真核藻类的季节变化规律和聚球藻相反。A time-series station（118°E,21.5°N） was assigned to study the seasonal and diurnal variations of size-frac-tionated chlorophyll a（Chl a） and picophytoplankton（Prochlorococcus,Synechococcus,and picoeukaryotes） in the northeastern South China Sea in spring,autumn 2014 and summer 2015,respectively.Chl a concentration showed remarkable diel variations,with the highest concentration of spring occurred in the midday.In summer and autumn,Chl a concentration generally increased in the daylight and decreased in the nighttime.However,Chl a concentration was low in the midday of summer because of the photoinhibition.Picophytoplankton（0.2~3 μm） was the major contributor to the total Chl a（pico-Chl a/total Chl a〉71.49 %）,and micro-phytoplankton（〉20 μm） was the minor one（micro-Chl a/total Chl a10.41 %）.Three groups of picophytoplankton were identified by using flow cytometry.In the three seasons,Prochlorococcus was the most abundant in Station A with the maximum abundance 1.05×10^5 cells/m L,followed by Synechococcus.Picoeukaryotes were the minor group but probably contributed most to Chl a due to the higher cellular Chl a content.Among various factors,light is a key factor to control the diurnal variations of Chl a and picophytoplankton.Synechococcus abundance generally decreased during the day and increased from dusk to midnight.Higher abundance of picoeukaryotes occurred during the day and the lower occurred during the night in autumn and summer.An opposite diel variation was observed in spring for picoeukaryotes.The diel variation of Prochlorococcus was similar to picoeukaryotes in spring and autumn.There was no statistical difference of Prochlorococcus abundance between seasons（P〉0.05）.The abundance of Synechococcus was the highest in autumn,followed by summer and spring,while the seasonal variation of picoeukaryotes was opposite to that of Synechococcus.

关 键 词：分粒级叶绿素a 超微型光合生物 昼夜变化 季节变化 南海东北部 

分 类 号：Q178.1[生物学—水生生物学] P735[生物学—普通生物学]