海洋生态与环境科学重点实验室知识库

浮游纤毛虫是一类具有纤毛的单细胞原生动物，隶属于原生动物亚界（Protozoa）－纤毛门（Ciliophora）－旋毛纲（Spirotrichea）－寡毛亚纲（Oligotrichina）及环毛亚纲（Choreotrichia），包括无壳纤毛虫和砂壳纤毛虫。浮游纤毛虫个体微小（多数体长在10－200 μm之间），且分布广泛，是海洋微型浮游动物重要组成部分。浮游纤毛虫是pico-（0.2－2 μm）和nano-（2－20 μm）级海洋浮游生物的摄食者，又是中型浮游动物和仔稚鱼等的重要食物供应者，是连接微食物网和经典食物链的重要中介，在海洋生态系统的物质循环和能量流动中发挥重要作用。因此对浮游纤毛虫生态学的研究具有重要意义。

浮游纤毛虫在各海区不同水层中的垂直分布和群落变化研究较少，本论文研究了热带大洋海山区（雅浦、马里亚纳和卡罗琳海山）、近岸海区（南海北部陆架陆坡海区）、大洋至近岸海区（热带西太平洋和南海北部陆架陆坡海区）和热带至寒带海区（热带西太平洋、白令海和北冰洋海区）中浮游纤毛虫的垂直分布和群落特征（含无壳纤毛虫粒级、砂壳纤毛虫所占丰度比例、口径组、冗余度等），并对浮游纤毛虫丰度与温度、盐度和叶绿素之间的关系进行了初步探讨。

分别于2014年12月至2015年1月、2016年3月至4月和2017年7月至8月对雅浦（水深300－5000 m）、马里亚纳（水深30－5000 m）和卡罗琳海山区（水深50－5000 m）中浮游纤毛虫的垂直分布以及其群落结构进行了研究。雅浦、马里亚纳和卡罗琳海山中，浮游纤毛虫丰度和生物量垂直分布均为“双峰”型，即表层和深层叶绿素a最大值（Deep Chlorophyll a Maximum，DCM）层有高值，丰度范围分别为0－331 ind./L，0－405 ind./L和0－405 ind./L，生物量范围分别为0.0－0.6 μg C/L，0.0－0.9 μg C/L和0.0－1.1 μg C/L。浮游纤毛虫群落特征中，无壳纤毛虫是浮游纤毛虫的最主要类群，大于50μm粒级无壳纤毛虫所占丰度比例从表层至底层逐渐降低。砂壳纤毛虫丰度占总纤毛虫的丰度比例小于10%。根据各砂壳纤毛虫种类分布水层的不同，我们将其分为了四个类群（I：0－100 m水层；II：50－200 m水层；III：100 m以深水层和V：各水层均有分布），其中类群I和V是优势类群。三个海区中28－32 μm口径组均是种类数最多的口径组，但是砂壳纤毛虫所占丰度比例最大口径组却均为24－28 μm。雅浦、马里亚纳和卡罗琳海山区中冗余度分别为79.0%、79.5%和78.9%。雅浦、马里亚纳和卡罗琳海山共鉴定出砂壳纤毛虫33属89种，广布型和暖水型是砂壳纤毛虫的优势类群，分别占砂壳纤毛虫总种类数的93.5%、93.2%和94.7%。未发现近岸型砂壳纤毛虫。三个海山中浮游纤毛虫丰度和温度均呈显著正相关关系。

于2017年3月对南海北部陆架陆坡海区（水深110－2000 m）中浮游纤毛虫的垂直分布以及其群落结构进行了研究，发现调查海域存在一个中尺度的反气旋暖涡，结合调查期间每日卫星数据和海区水文垂直分布特征，将调查海区分为暖涡外和暖涡内海区。暖涡外和暖涡内海区中，浮游纤毛虫丰度和生物量的垂直分布分别为“表层高”和“双峰”型，暖涡外和暖涡内浮游纤毛虫丰度分别为2－767 ind./L和14－458 ind./L，生物量分别为0.0－2.7 μg C/L和0.0－1.3 μg C/L。暖涡外表层纤毛虫丰度值高于暖涡内。浮游纤毛虫群落特征中，从表层至DCM层10－20 μm粒级无壳纤毛虫丰度占总无壳纤毛虫丰度比例在暖涡外均低于暖涡内，同时砂壳纤毛虫丰度占总纤毛虫丰度比例平均值和暖涡内站位相比低了约2%。类群I和V砂壳纤毛虫是暖涡外和暖涡内砂壳纤毛虫的优势类群（丰度高值分别在表层和DCM层），但暖涡外表层类群I和V的丰度比例差值比暖涡内低31%。暖涡外砂壳纤毛虫口径组数、种丰富度和冗余度均高于暖涡内。时间序列站中，浮游纤毛虫白天和夜间的垂直分布均为“双峰”型，但是夜间各层丰度和生物量均高于白天，浮游纤毛虫可能具有昼夜垂直迁移现象。

分别于2015年6月和2015年11月至12月对南海北部陆架陆坡海区（水深110－2000 m）和热带西太平洋大断面（水深均大于2000 m）中浮游纤毛虫的垂直分布以及其群落结构进行了研究。热带西太平洋和南海北部陆架陆坡海区中，浮游纤毛虫的垂直分布分别为“双峰”型和 “表层高”，浮游纤毛虫的丰度分别为0－443 ind./L和2－809 ind./L，生物量分别为0.0－0.7 μg C/L和0.0－1.4 μg C/L。南海北部陆架陆坡受珠江冲淡水（近岸水）入侵影响的站位中，表层浮游纤毛虫的丰度值远远高于南海陆坡水。浮游纤毛虫群落特征中，无壳纤毛虫是主要的组成类群，砂壳纤毛虫所占丰度比例在近岸水（1.5%）小于陆坡水（6.4%）和热带西太平洋大洋水（5.9%）。热带西太平洋海区中砂壳纤毛虫口径组数、种丰富度和冗余度均高于南海北部陆架陆坡海区。砂壳纤毛虫主要由类群I和类群V组成，并且丰度高值分别出现在表层和DCM层。500 m以深水层未发现砂壳纤毛虫。我们推测无壳纤毛虫类群也和砂壳纤毛虫类群相似，可以分为表层高类群和DCM层高类群。同样在表层和DCM层的浮游生物食物网的结构和功能则也有可能不同。

分别于2015年11月至12月、2016年7月和8月对热带西太平洋大断面（水深均大于2000 m）、白令海（水深均大于500 m）和北冰洋海区（水深均大于200 m）中浮游纤毛虫的垂直分布以及其群落结构进行了研究。热带西太平洋、白令海和北冰洋海区中浮游纤毛虫丰度和生物量的垂直分布分别为“双峰”型、“表层高”和“DCM层高”。在热带西太平洋、白令海和北冰洋海区0－200 m水层中，丰度分别为35－443 ind./L、152－3267 ind./L和12－1615 ind./L，生物量分别为0.0－0.7 μg C/L、0.3－11.6 μg C/L和0.0－4.5 μg C/L。浮游纤毛虫群落特征中，砂壳纤毛虫丰度占总纤毛虫丰度比例在白令海海区（42.6%）要高于热带西太平洋（7.8%）和北冰洋海区（2.0%）。10－20 μm粒级无壳纤毛虫丰度占总无壳纤毛虫丰度比例在热带西太平洋海区中最高，而白令海和北冰洋中大于30 μm粒级无壳纤毛虫在各水层中所占比例均高于热带西太平洋海区。混合营养纤毛虫丰度及其占总无壳纤毛虫丰度比例在白令海和北冰洋海区均高于热带西太平洋海区。热带西太平洋海区小口径组（12－16 μm）砂壳纤毛虫占总砂壳纤毛虫丰度比例最高，而北冰洋海区中则是大口径组（60－64 μm）所占丰度比例最高。砂壳纤毛虫的冗余度从北冰洋到热带西太平洋海区是增加的。三个海区中无壳纤毛虫丰度与温度和Chl a浓度均呈极显著正相关关系。

本论文对各海区中浮游纤毛虫的垂直分布和群落结构特征进行对比，发现从大洋至近岸海区中，浮游纤毛虫的垂直分布由“双峰”型变成“表层高”，砂壳纤毛虫种类数、冗余度等均降低；从热带至寒带海区中，砂壳纤毛虫种类数、口径组数和冗余度等特征均呈降低趋势，但是无壳纤毛虫粒级和优势砂壳纤毛虫口径组却呈增大的趋势。温度可能是影响浮游纤毛虫丰度的重要的影响因素。

Planktonic ciliates are unicellular, eukaryotic protists with cilium around its body which belong to Protozoan－Ciliophora－Oligotrichea－Oligotrichina and Tintinnina, including aloricate ciliates and tintinnids. Planktonic ciliate are small size (size range of 10－200 μm), living with planktonic life and ubiquitous in various marine habitats. Planktonic ciliates are primary consumers of pico-(0.2－2 μm) and nano-(2－20 μm) sized producers, and are important food sources for metazoan and fish larvae. As the dominant component of the microzooplankton, the marine planktonic ciliate is a key medium through microbial food web to classical food chain, which plays an important role in material circulation and energy flow of marine ecosystem. Therefore, it’s very important to understand ecology roles of planktonic ciliates.

Fundamental research about the vertical distribution and community structure variation of planktonic ciliates in different seas were rare. In this dissertation, we studied planktonic ciliates vertical distribution and community structure in the tropical oceanic area (the Yap, Mariana and Caroline seamounts), shelf area (the northern South China Sea (nSCS)), the oceanic to shelf area (the tropical western Pacific and the nSCS) and the tropical to cold area (the tropical western Pacific, the Bering Sea and the Arctic Ocean). The community structure including aloricate ciliate size-fraction, proportion of tintinnid abundance to total ciliate, lorica oral diameter (LOD) size-class and redundancy of tintinnid species and so on. Eventually, we carried out a preliminary study about the relationship between the ciliate abundance and temperature, salinity and the chlorophyll a in different seas.

The vertical distribution and community structure of planktonic ciliates were investigated in the Yap (depths 300－5000 m), Mariana (depths 30－5000 m) and Caroline seamounts (depths 50－5000 m) of the tropical western Pacific from December 2014 to January 2015, March to April 2016 and July to August 2017, respectively. In the Yap, Mariana and Caroline seamounts, vertical distribution pattern of planktonic ciliates abundance and biomass both showed “bimodal-peak”, with high anundance and biomass value appeared in the surface and DCM (Deep Chlorophyll a Maximum) layers. Planktonic ciliate abundance ranged from 0－331 ind./L, 0－405 ind./L and 0－405 ind./L, respectively. Biomass ranged from 0.0－0.6 μg C/L, 0.0－0.9 μg C/L and 0.0－1.1 μg C/L, respectively. For planktonic ciliate community structure, the aloricate ciliates were the dominant groups in three seamounts, and the abundance proportion of the above 50 μm size-fraction to total aloricate ciliate decreased from surface to the bottom. The proportion of tintinnid abundance to total ciliate was less than 10%. According to the inhabited depth, tintinnid could be divided into four groups: I: 0－100 m depth; II: 50－200 m depth; III: > 100 m depth and V: occured in each depth. Group I and V were the dominant tintinnid groups. The 28－32 μm LOD size-class had the top species richness while the 22－28 μm LOD size-class had the top abundance proportion of tintinnids in three seamounts. The redundancy in the Yap, Mariana and Caroline seamounts were 79.0%, 79.5% and 78.9%, respectively. In the Yap, Mariana and Caroline seamounts, 89 tintinnid species of 33 genera were identified. Among them, Cosmopolitan and warm water were the main genera in three seamounts which occupied 93.5%, 93.2% and 94.7% in total tintinnids species richness, respectively. No neritic species were found in three seamounts. Relationshilp between ciliate abundance and temperature showed positive correlation.

The vertical distribution and community structure of planktonic ciliates were investigated in the northern South China Sea (nSCS, depths 110－2000 m) from March 2017. We found a meso-scale anti-cyclonic warm eddy in the survey stations. Combined the satellite data and the hydrography during the survey stations, we classified the nSCS into the reference stations and the warm eddy center areas. In the reference stations and the warm eddy center areas, vertical distribution pattern of planktonic ciliates abundance and biomass showed “surface-peak” and “bimodal-peak”. In the reference stations and warm eddy center, ciliate abundance ranged from 2－767 ind./L and 14－458 ind./L, respectively. Ciliate biomass ranged from 0.0－2.7 μg C/L and 0.0－1.3 μg C/L, respectively. At the reference stations, the surface abundance was higher than in the warm eddy center. For planktonic ciliate community structure, the 10－20 μm size-fraction of aloricate ciliate was less abundant from surface to DCM layers in the reference stations than in the eddy center, and the average ratio of tintinnid to total ciliate abundance in the reference stations was about 2% lower than in the eddy center. The vertical distribution of tintinnid species groups I and V had higher abundances in the reference stations than in the warm eddy center showed surface and DCM peaks, respectively. But the difference value between the groups I and V of the surface layer in the reference stations was 31% lower than in the warm eddy center. In the reference stations, the number of lorica oral diameter (LOD) size-classes, species richness, and ratio of redundant species were also larger than in the warm eddy center. In the time series station, ciliate vertical distribution pattern was bimodal-peak in both the day and night time. But ciliate average abundance of each depth in the night time was higher than in the day time. Planktonic ciliate may conduct diel vertical migration.

 The vertical distribution and community structure of planktonic ciliates were investigated in the nSCS (depths 110－2000 m) and the tropical western Pacific (depths above 2000 m) from June 2015 and November to December 2015, respectively. In the tropical western Pacific and the nSCS, vertical distribution pattern of planktonic ciliates abundance and biomass showed “bimodal-peak” and “surface-peak”, respectively. Ciliate abundance ranged from 2－767 ind./L and 14－458 ind./L, and biomass ranged from 0.0－2.7 μg C/L and 0.0－1.3 μg C/L, respectively. At stations influenced by shelf water, the surface abundance was much greater than in slope waters. For planktonic ciliate community structure, the aloricate ciliates were the dominant groups, tintinnid abundance to total ciliate of the surface layer in the shelf water (1.5%) was less than in the slope water (6.4%) and tropical western Pacific (5.9%). Both the tintinnid species number, LOD size-classes number and the redundancy in the tropical western Pacific were higher than in the nSCS. Within the ciliates, the vertical distribution of tintinnid species groups I and V had higher abundances overall and showed surface and DCM peaks, respectively. There was no tintinnid species below 500 m depth in our study. We speculate that aloricate ciliates might also have surface peak and DCM peak groups. The overall vertical distribution patterns showed that the planktonic food web may function differently within the surface waters and the DCM layer.

The vertical distribution and community structure of planktonic ciliates were investigated in the the tropical western Pacific (water depths above 2000 m), the Bering Sea (water depths above 500 m) and the Arctic Ocean (water depths above 200 m) from November to December 2015, July to August 2016, respectively. In the tropical western Pacific, the Bering Sea and the Arctic Ocean, vertical distribution pattern of planktonic ciliates abundance and biomass showed “bimodal-peak”, “surface-peak” and “DCM-peak”, respectively. Ciliate abundance ranged from 35－443 ind./L, 152－3267 ind./L and 12－1615 ind./L, respectively. Ciliate biomass ranged from 0.0－0.7 μg C/L, 0.3－11.6 μg C/L and 0.0－4.5 μg C/L, respectively. For planktonic ciliate community structure, the abundance proportion of tintinnid to total ciliate in the Bering Sea (42.6%) was higher than both the tropical western Pacific (7.8%) and the Arctic Ocean (2.0%). The abundance proportion of 10－20 μm size-fraction aloricate ciliates in the tropical western Pacific was highest in these three seas, while abundance proportion of aloricate ciliate above 30 μm size-fraction in each depth in the Bering Sea and the Arctic Ocean were larger than the tropical western Pacific. In the Bering Sea and the Arctic Ocean, abundance and abundance proportion of mixotrophic ciliate to total aloricate ciliate were higher than in the tropical western Pacific. The tropical western Pacific had higher abundance proportion of tintinnids in smaller LOD (lorica oral diameter, 12－16 μm) size-class, while the Arctic Ocean had higher abundance proportion of tintinnids in larger LOD (60－64 μm) size-class. Proportion of redundant species increased from the Arctic Ocean to the tropical western Pacific. Relationship between the aloricate ciliate abundance and temperature, Chl a concentration showed strong positive correlation.

In this dissertation, we compared planktonic ciliates vertical distribution and community structure variation in different seas. From oceanic to shelf seas, vertical distribution pattern of planktonic ciliates changed from “bimodal-peak” into “surface-peak”, and both the tintinnid species number and redundancy decreased. From tropical to cold areas, tintinnid species number, LOD size-class number and redundancy decreased, while aloricate ciliate size-fraction and dominant tintinnid LOD size-class become larger. Temeperature maybe the main influence factor of ciliate abundance.