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基于稳定同位素方法的南大洋优势浮游动物饵料来源与营养级分析
张晔
Subtype博士
Thesis Advisor李超伦
2016-05
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Discipline海洋生态学
Keyword普里兹湾 南设得兰海域 浮游动物 南极大磷虾 稳定性同位素
Abstract由于其独特的地理位置和环境特征,南大洋对全球气候变化有快速、重要的反应,是研究海洋生态系统对全球变化响应与反馈的重要窗口。浮游动物是海洋生态系统的重要组成部分,它们摄食浮游植物等初级生产者,同时为高营养级消费者提供饵料,在食物网中作为物质与能量的传输通道,有着承上启下的重要作用。本文利用2012/2013年度(第29次)和2013/2014年度(第30次)中国南极科学考察(CHINARE)期间采集的普里兹湾和南设得兰海域浮游动物样品,对优势浮游动物种类的丰度、分布及种群结构进行了分析。同时对主要浮游动物种类的碳氮稳定性同位素进行了测定,基于氮同位素值剖析了普里兹湾及南设得兰海域夏季优势浮游动物的营养级水平。基于Isosource模型,定量分析了南极大磷虾在南大洋夏季的饵料来源组成特征,并结合环境参数对南极大磷虾营养策略进行了剖析,以期确定浮游食物网基本结构和主要种类的食物关系,深化对南大洋生态系统能流物流过程的了解和认知。
2012/2013年度夏季普里兹湾的调查结果显示,调查期间海冰已经基本融化至69°S,叶绿素浓度为0.01-0.97 μg/L。远海浮游动物群落的整体丰度大于近岸群落,桡足类是群落丰度的最大贡献者,占据浮游动物总丰度的95%以上。大磷虾及其他类群丰度相对较低。本次调查共采集获得浮游动物37种(类),其中尖角似哲水蚤(Calanoides acutus)、近缘哲水蚤(Calanus propinquus)、南极大磷虾(Euphausia superba)和拟长臂樱磷虾(Thysanoessa macrura)等南大洋广泛分布的优势浮游动物种类在调查海域均有分布。尖角似哲水蚤在各个站位丰度为10–7180 ind/1000 m3,平均丰度为1601.0 ind/1000 m3。近缘哲水蚤的丰度为30–4480 ind/1000 m3,平均丰度为1158.3 ind/1000 m3。大磷虾在各个站位丰度为10–880 ind/1000 m3,平均丰度为233.9 ind/1000 m3。拟长臂樱磷虾主要分布在远洋海域站位,在陆坡和近岸海域并没有发现,其丰度为10–240 ind/1000 m3,平均丰度为82.2 ind/1000 m3,低于南极大磷虾。
对2012/2013夏季普里兹湾14种主要浮游动物的碳氮稳定同位素进行了测定,结果显示:碳稳定性同位素值为-29.92‰至-26.01‰,氮稳定性同位素值为1.88‰至7.09‰。基于氮稳定同位素值获得了这些浮游动物的营养级水平组成。大磷虾和螺的营养级较低(2.12–2.13),近缘哲水蚤、巨锚哲水蚤、尖角似哲水蚤等偏植食性桡足类营养级为2.3–2.9,杂食性或偏肉食性的戈氏长腹水蚤、拟长臂樱磷虾、晶磷虾的营养级为2.9–3.2,肉食性的箭虫、𧊕、海萤、三脊刺磷虾Euphausia triacantha、南极拟真刺水蚤的营养级最高(3.4–3.5)。
南极大磷虾的幼体和成体碳稳定同位素值分别为–27.48‰和–28.26‰,氮稳定同位素值分别为1.69‰和2.78‰。基于Isosource模型定量估算了大磷虾的饵料组成。结果表明,在普里兹湾夏季,表层0 m,25 m和50 m的颗粒有机物(POM)合并得到的POM(0/25/50 m)贡献了大磷虾幼体食物组成的大部分(56–69%),中型浮游动物(mesozooplankton)是第二重要的饵料来源(13–34%),而深水层POM(100 m,200 m)和浮冰生物对大磷虾幼体食物组成分别贡献了0–24%,0–19%和0–13%。大磷虾成体的模型结果和幼体的所有不同:中型浮游动物是大磷虾成体的最主要食物源(58–71%),50 m以浅的POM(0/25/50 m)占有26–34%的食物组成;其他的潜在食物源深层POM(100 m)、POM(200 m)和浮冰生物共同组成了大磷虾成体食物的剩余部分,分别为0–11%,0–9%和0–6%。将两部分模型结果合起来可以得出,大磷虾主要的两种食物源POM(0/25/50 m)和中型浮游动物对幼体和成体的食物贡献比例不同。随着大磷虾由幼体发育到成体,POM(0/25/50 m)对大磷虾食物的贡献降低,而中型浮游动物对大磷虾食物的贡献比例增大。
2013/2014夏季南设得兰海域的调查结果显示,南极大磷虾的丰度(10.0–656720.0 ind/1000 m3,平均丰度为44403.9 ind/1000 m3)高于拟长臂樱磷虾(10.0–650.0 ind/1000 m3,平均丰度为132.9 ind/1000 m3),且它们的水平分布存在一定程度的空间分离。在研究海域东部的南奥克尼群岛(South Orkneys)附近发现了大量南极大磷虾原蚤状CI期幼体,推测南极大磷虾于2014年1月左右进行了种群补充,且由种群结构分布显示部分幼体已经发育至FI期并向南部外海迁移。尖角似哲水蚤和近缘哲水蚤在南设得兰海域的空间分布较为广泛,且两者分布基本一致。
2013/2014年夏季南设得兰周边海域9种浮游动物的氮稳定同位素值在3.29‰–5.01‰之间,营养级水平为2.00–3.37。巨锚哲水蚤作为典型的滤食物种,其营养级最低;𧊕的营养级水平相对较低;拟长臂樱磷虾是我们所获取的浮游动物中最高营养级物种,高于典型的肉食性物种南极拟真刺水蚤。南设得兰海域南极大磷虾的幼体和成体碳稳定同位素值分别为–27.05‰和–26.86‰,氮稳定同位素值分别为3.72‰和3.82‰。Isosource模型结果显示,调查期间南极大磷虾的饵料主要以浮游植物和浮冰生物为主,而POM对大磷虾饵料的贡献较低。浮游植物对南极大磷虾食物贡献大于60%,浮冰生物对大磷虾的食物贡献约为30%左右。大磷虾幼体和成体的饵料分布并没有太大差异,这一结果与2012/2013年度普里兹湾的模型结果不同。普里兹湾调查期间做站海域浮冰已经融化,大磷虾主要依靠水体中的浮游植物和浮游动物为食;而南设得兰海域调查期间浮冰正处于融化期间,大量海冰融化使得水体中有大量的浮游植物和冰藻存在。水体中较高的叶绿素浓度表明此时植物性饵料充足,此时大磷虾的幼体和成体均主要依赖浮游植物。饵料的可获得性决定着南极大磷虾的摄食类群。大磷虾的摄食策略较为灵活,在不同海域和季节,大磷虾都能够摄食其可获得的饵料来源以满足生长发育的需求。
Other AbstractBecause of the unique geographic condition and environmental characteristic, Southern Ocean has quick and important response towards global climate change, and it is also the key to research the feedback of global changes for marine ecosystem. Zooplankton is an important component in marine ecosystem. As a linkage between producers such as phytoplankton and higher consumers, zooplankton plays a key role in material and energy flow. In this study, we investigated the population dynamics of four dominant zooplanktonic species in Prydz Bay and South Shetland Islands, Antarctica using zooplankton samples and environmental factors based on 2012/2013 (29th) and 2013/2014 (30th) CHINARE. The trophic levels as well as the stable isotope values of main zooplankton in Prydz Bay and South Shetland Islands, Antarctica were analysed. Also, the diet source compositions of Antarctic krill were quantitatively estimated based on Isosource model output. The strategy of feeding patterns of Antarctic krill as well as the basic planktonic food web and main feeding interactions were analysed then to perceive the energy flow process in Southern Ocean.
The survey results in Prydz Bay during 2012/2013 summer showed that the seasonal sea ice had thawed to south of 69°S during our survey time, and the Chl a concentrations were 0.01-0.97 μg/L. The abundance of oceanic community was higher than that of neritic community. Copepods contributed more than 95% of the total zooplankton abundance. Krill and other groups had a relatively low abundance. 37 species (groups) were collected and obtained in this survey, and Calanoides acutus, Calanus propinquus, Euphausia superba (Antarctic krill) and Thysanoessa macrura which are widely distributed in Southern Ocean were all found in Prydz Bay. The abundance of C. acutus was 10–7180 ind/1000 m3, and the mean abundance was 1601.0 ind/1000 m3. The abundance of C. propinquus was 30–4480 ind/1000 m3, and the mean abundance was 1158.3 ind/1000 m3. The abundance of E.superba was 10–880 ind/1000 m3, and the mean abundance was 233.9 ind/1000 m3. T. macrura were distributed at oceanic stations rather than at shelf and neritic regions. The abundance of T. macrura was 10–240 ind/1000 m3, and the mean abundance was 82.2 ind/1000 m3, lower than Antarctic krill.
The carbon and nitrogen stable isotope values of 14 main planktonic species in Prydz Bay during summer in 2012/2013 showed that the carbon stable isotope values were from -29.92‰ to -26.01‰, whereas the nitrogen stable isotope values were from 1.88‰ to 7.09‰. The trophic levels of these planktonic species were obtained based on nitrogen stable isotope values. The trophic levels of E. superba and clio sp. were low (2.12–2.13), and herbivorous copepods C. propinquus, Rhincalanus gigas, C. acutus had trophic levels of 2.3–2.9. Omnivorous or partially carnivorous species Metridia gerlachei, T. macrura, Euphausia crystallorophias had trophic levels of 2.9–3.2, and carnivorous species Sagitta sp., Vibiliidae sp., Conchoecia innominata, Euphausia triacantha and Paraeuchaeta antarctica had highest trophic positions (3.4–3.5).
The carbon isotope values of juvenile and adult of Antarctic krill were –27.48‰ and –28.26‰, respectively; whereas the nitrogen isotope values of those were 1.69‰ and 2.78‰, respectively. The Isosource model was used to quantitatively estimate the feasible contribution of different food sources to the diet of Antarctic krill. The output showed that for juvenile krill in Prydz Bay during austral summer, POM from 0 m, 25 m, and 50 m combined (POM(0/25/50 m)) appeared to constitute the majority of the diet (56–69%), with mesozooplankton as an important secondary food source (13–34%); POM in deeper water layers (100 m, 200 m), and ice biota at 0–24%, 0–19%, and 0–13%, respectively, apparently contributed less to the diet. For adult krill, mesozooplankton was the major food source (58–71%), followed by POM (0/25/50 m) (26–34%); other potential food sources made up the remainder of the diet: POM (100 m) (0–11%), POM (200 m) (0–9%), and ice biota (0–6%). These two output indicated different contributions of POM (0/25/50 m) and mesozooplankton to the diet of krill among stages. As Antarctic krill matured, the contribution of POM(0/25/50 m) to the diet decreased, while that of mesozooplankton increased; this represents an ontogenetic diet shift from POM (0/25/50 m) to mesozooplankton.
In around South Shetland Islands, Antarctica during austral summer of 2013/2014, the abundance of E. superba (10.0–656720.0 ind/1000 m3, with mean abundance 44403.9 ind/1000 m3) was higher than that of T. macrura (10.0–650.0 ind/1000 m3, with mean abundance 132.9 ind/1000 m3), and these two krill shared different areas. A large amount of the first calyptopis stage of E. superba were found around South Orkneys, which indicated that E. superba reproduced in early days of January in 2014. The population structure distribution showed that a part of calyptopis has developed into furcilia stages and drifted to south oceanic region. C. acutus and C. propinquus distributed widely in around South Shetland Islands, Antarctica, and these two copepods distributed similarly.
The carbon stable isotope values of 9 main planktonic species in around South Shetland Islands, Antarctica during summer in 2013/2014 showed that the nitrogen stable isotope values were from 3.29‰ to 5.01‰. The trophic levels of these planktonic species were from 2.00 to 3.37. As a typical filter feeder R. gigas has lowest trophic level; and Vibiliidae sp. has low trophic level in this sea area. T. macrura was the highest trophic level species based on species we obtained, higher than carnivorous species P. antarctica. In around South Shetland Islands, Antarctica, the carbon isotope values of juvenile and adult were –27.05‰ and –26.86‰, respectively, whereas the nitrogen isotope values of those were 3.72‰ and 3.82‰, respectively. The Isosource model output showed that in our survey time, Antarctic krill relied mostly on phytoplankton and ice biota for food. While POM contributed little to krill diet. Phytoplankton made up more than 60% of the diet of krill, and ice biota appeared to constitute about 30% of the diet of krill. The diet composition distribution of juvenile and adult krill were similar based on the the outputs, which was different from the outputs based on data in Prydz Bay. In the Prydz Bay survey, the floating ice was mostly thawed, thus Antarctic krill consumed POM and mesozooplankton as their food. Whereas in South Shetland Islands, Antarctica the large floating ice were thawing, and the phytoplankton and ice algae were abundant in the water. On this condition, juvenile and adult krill might both rely on phytoplanktonic diets. The availability of food sources is the key factor of what krill eat. Antarctic krill has flexible feeding patterns, and they would consume available food to meet their needs at different sea area or season.
Language中文
Document Type学位论文
Identifierhttp://ir.qdio.ac.cn/handle/337002/116994
Collection海洋生态与环境科学重点实验室
Affiliation1.中国科学院大学
2.中国科学院海洋研究所
Recommended Citation
GB/T 7714
张晔. 基于稳定同位素方法的南大洋优势浮游动物饵料来源与营养级分析[D]. 北京. 中国科学院大学,2016.
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