中国科学院海洋研究所机构知识库

      浮游动物是食物网中初级生产者与高级消费者之间的营养纽带，并且通过摄 食、排粪、被动沉降等过程调节颗粒有机碳从表层向深海输送，因此，了解浮游 动物的群落结构及其碳循环中的作用变得越来越重要。本研究基于中国第 36 次 南极科学考察期间（2019 年 12 月至 2020 年 1 月）于南极宇航员海使用北太平 洋网（网口 0.5 m²，筛绢孔径 330 μm）和 Multinet 网（网口 0.5 m²，筛绢孔径 200 μm）采集的浮游动物样品，对调查海域浮游动物的丰度、群落结构、优势种 种群结构及其与环境因子之间的关系进行了研究，并探讨了宇航员海域夏季浮游 动物被动沉降对碳通量的贡献。

      2019/2020 年南极夏季宇航员海浮游动物主要由桡足类、磷虾、毛颚类、浮 游被囊类等类群组成，其丰度在 8.9-102.0 ind.m^-3 之间，最高丰度记录在宇航员 海中部靠北区域。调查海域桡足类丰度对浮游动物总丰度的贡献可达 90%以上，其中、大中型桡足类 Calanoides acutus、Metridia gerlachei、Calanus propinquus 和 Rhincalanus gigas 分布广泛，而小型桡足类 Oithona similis、Oithona frigida、Ctenocalanus citer、Oncaea conifera 等在数量上占比较高。通过聚类分析可将宇 航员海浮游动物在区域上划分为 5 个群落，普里兹湾涡流、威德尔涡流、南极绕 极流等水文动力过程是宇航员海浮游动物群落分布模式的主要控制因素，另外， Bio-env 分析显示，饵料（叶绿素a）也对该海区浮游动物的种群和群落结构具有重要影响。

      在宇航员海域浮游动物垂直分布上，浮游动物可划分为上层、中层和深层等 3 个群落，上层群落主要由 0-100 m 水层样品组成，其浮游动物平均丰度为 178.4 ind.m^-3，优势种为 C. acutus、C. propinquus、M. gerlachei、R. gigas、O. similis、 O. frigida、Oncaea antarctica 等；中层群落主要由 100-500 m 水层样品组成，其 浮游动物平均丰度为 15.0 ind.m^-3，优势种为 O. conifera、Aetideopsis minor、 Bathycalanus bradyi、Heterorhabdus autrinus、Paraeuchaeta antarctica；深层群落 主要由 500-1500 m 水层采集的浮游动物样品组成，其浮游动物平均丰度为 2.2 ind.m^-3，优势种为 A. minor 和 B. bradyi。这种群落划分很大程度上归因于浮游动 物优势物种丰度尤其是桡足类丰度的差异而不是浮游动物物种组成的变化，具有水深特异性的温度、盐度、叶绿素等环境因子是浮游动物垂向分布的关键影响因 素。

      优势桡足类 C. acutus、C. propinquus、R. gigas 和 M. gerlachei 在各水层的自 然死亡比例具有明显的物种差异，其中 M. gerlachei 在调查站位均未发现死亡个 体，其它三个物种自然死亡比例随着水层的增加大体呈现增加的趋势，其中在中 深层水体（500-1500 m）的自然死亡比例可达 50%左右。宇航员海夏季浮游动物 被动沉降在数量来源组成上主要由小型桡足类构成，在有机碳碳含量组成上主要 由优势桡足类（C. acutus、C. propinquus 和 R. gigas）的残骸和蜕皮组成。夏季 初期宇航员海浮游动物被动沉降对不同水层碳通量的贡献从表层水体（100-200 m）的 0.08%，增加到中深层水体的 0.15%。

      Zooplankton is usually considered as trophic links between primary producers and higher trophic level species. Zooplankton also plays a substantial role in organic carbon exporting from the ocean surface to interior through feeding, fecal pellets and passive sinking. It is important to study the composition of zooplankton community and its contribution to carbon pump. Based on zooplankton samples collected using a Norpac Net (0.5 m², 330 μm mesh size) and a Multinet (0.5 m², 200 μm mesh size) in Cosmonaut Sea during the 36th Chinese National Antarctic Research Expedition (December 2019 to January 2020), we studied zooplankton community structure, abundance, population structure of dominant species and their relationship with environmental factors. We also investigated the contribution of zooplankton passive sinkers to carbon flux in Cosmonaut Sea.

      Zooplankton in Cosmonaut Sea in the summer of 2019/2020 varied from 8.93 ind.m^-3 to 102.0 ind.m^-3, with the highest value recorded in the northern part of sampling region. Zooplankton is mainly composed of copepods, krill, chaetognaths and tunicates. Zooplankton abundance at each station is maily composed of copepods (more than 90%). The large copepods, C. acutus, M. gerlachei, C. propinquus and R. gigas, were widely distributed in the survey area, while small copepods like O. similis, O. frigida, C. citer, and O. conifera were numerically dominant. Five groups of zooplankton community, broadly linked to physical oceanographic processes like the Prydz Bay Gyre, Weddell Gyre, and Antarctic Circumpolar Current, were divided based on cluster analysis. Food availability (chlorophyll a) also had an important impact on the population structure and community structure of zooplankton. Three zooplankton communities, namely a surface community (0-100 m), mesopelagic community (100-500 m) and an upper bathypelagic community (500-1500 m), were identified based on samples collected using a Multinet (0.5 m², 200 μm mesh size) in the 0-1500 m water column. The surface community, mainly included copepods C. acutus, C. propinquus, M. gerlachei, R. gigas, O. similis, O. frigida and O. antarctica, was typified by the highest abundance (178.4 ind.m^-3). The mesopelagic community showed moderate abundance (15.0 ind.m^-3) and the dominant species were O. conifera, A. minor, B. bradyi, H. autrinus and P. antarctica. The upper bathypelagic community, characterized by the lowest abundance (2.2 ind.m^-3), was dominated by deep-water copepods like A. minor and B. bradyi. This community structure was mainly due to the variation in the abundance of dominant species, especially the copepods, rather than the variation in species composition. The depth-related differences in environmental factors had strong influences on the vertical pattern of zooplankton community.

     The dominant copepods C. acutus, C. propinquus, R. gigas and M. gerlachei showed significant differences in the natural mortality of each water strata. No dead M. gerlachei was found in the survey area, while the natural mortality of the other three copepods increased along the depth layer and was higher than 50% in the mesopelagic layer (500-1500 m). The passive sinking zooplankton during austral summer of Cosmonaut Sea was numerically dominated by small copepods, while carcasses and moults of dominant copepods (C. acutus、C. propinquus and R. gigas) made higher contribution to particulate organic carbon. The contribution of passive sinking zooplankton to carbon flux increased from 0.08% in the surface water (100-200 m) to 0.16% of the mesopelagic layer.

第 1 章 研究背景........................................................................................1

1.1 变化中的南大洋生态系统.............................................................................. 1

1.2 浮游动物在南大洋生态系统中的作用.......................................................... 2

1.3 南大洋浮游动物群落生态学研究进展.......................................................... 3

1.4 南大洋生物泵碳通量研究进展...................................................................... 4

1.4.1 生物泵的概念........................................................................................ 5

1.4.2 浮游动物被动沉降及其对生物泵碳通量的贡献................................ 5

1.4.3 浮游动物优势类群粪便对生物泵碳通量的贡献................................ 6

1.4.4 浮游动物群落组成、垂直移动及食性转变对生物泵碳通量的影响7

1.5 本文研究内容及意义...................................................................................... 9

1.5.1 本文研究内容........................................................................................ 9

1.5.2 研究意义.............................................................................................. 10

第 2 章 宇航员海浮游动物群落结构研究............................................. 11

2.1 引言................................................................................................................ 11

2.2 材料与方法.................................................................................................... 12

2.2.1 现场取样.............................................................................................. 12

2.2.2 样品和数据分析.................................................................................. 13

2.3 结果................................................................................................................ 14

2.3.1 环境因子.............................................................................................. 14

2.3.2 浮游动物群落...................................................................................... 15

2.3.3 桡足类优势物种的种群结构.............................................................. 20

2.3.4 环境因子对群落结构的影响.............................................................. 21

2.4 讨论................................................................................................................ 21

2.4.1 宇航员海浮游动物组成及群落结构.................................................. 21

2.4.2 环境因子对浮游动物群落的影响...................................................... 23

2.5 小结................................................................................................................ 24

第 3 章 宇航员海浮游动物垂直分布特征.............................................25

3.1 引言................................................................................................................ 25

3.2 材料与方法.................................................................................................... 26
3.2.1 现场取样.............................................................................................. 26

3.2.2 样品和数据分析.................................................................................. 27

3.3 结果................................................................................................................ 27

3.3.1 浮游动物群落垂直结构...................................................................... 27

3.3.2 桡足类优势种的种群垂直结构.......................................................... 30

3.4 讨论................................................................................................................ 31

3.4.1 宇航员海不同水层浮游动物物种组成及垂直分布特征.................. 31

3.4.2 宇航员海不同水层优势桡足类种群变动.......................................... 33

3.5 小结................................................................................................................ 33

第 4 章 宇航员海浮游动物被动沉降组成及其对碳通量的贡献........ 35

4.1 引言................................................................................................................ 35

4.2 材料与方法.................................................................................................... 36

4.2.1 样品采集.............................................................................................. 36

4.2.2 中性红染色实验.................................................................................. 37

4.2.3 实验室样品分析.................................................................................. 37

4.3 结果................................................................................................................ 38

4.3.1 优势桡足类死亡比例.......................................................................... 38

4.3.2 浮游动物被动沉降组成...................................................................... 39

4.3.3 浮游动物被动沉降通量...................................................................... 40

4.4 讨论................................................................................................................ 42

4.4.1 宇航员海浮游动物被动沉降的组成及指示意义.............................. 42

4.4.2 宇航员海浮游动物被动沉降对碳通量的贡献.................................. 42

4.5 小结................................................................................................................ 43

第 5 章 结论与展望................................................................................. 45

5.1 结论................................................................................................................ 45

5.2 展望................................................................................................................ 45

参考文献....................................................................................................46

附 录..........................................................................................................56

致 谢........................................................................................................57

作者简历及攻读学位期间发表的学术论文与研究成果.......................58