IOCAS-IR  > 海洋生态与环境科学重点实验室
我国近海水母沙海蜇的食物组成以及其与浮游动物群落的营养关系
王俊健
Subtype博士
Thesis Advisor李超伦
2020-08-21
Degree Grantor中国科学院大学
Place of Conferral中国科学院海洋研究所
Degree Name理学博士
Keyword沙海蜇 食性 食物组成 浮游动物 营养关系
Abstract

近二十年来,水母类在全球多个海域出现暴发现象,暴发的数量和频率都呈增加态势。由于水母种群数量增长迅速,并且对食物具有较强的竞争力,水母对海洋食物网的影响非常大。其暴发危害着海洋经济发展和海洋生态环境的健康。沙海蜇(Nemopilema nomurai)作为世界上最大的水母种类之一,在我国长江以北海域广泛分布,是我国近海经常暴发的灾害水母种类之一。为了调查沙海蜇在中国近海浮游生态系统中的营养地位,了解其在食物网能量流动中的作用,进一步明晰沙海蜇对海洋生态系统的影响,本研究利用稳定同位素和脂肪酸标记法,系统研究了不同时间段沙海蜇的食性、食物组成,以及其在浮游生物网中的营养地位。

首先,本研究第二部分利用20168月份黄东海处于生长高峰期的沙海蜇样本进行了稳定同位素和脂肪酸的分析,初步研究了沙海蜇的食性以及各类浮游生物对它的食物贡献率,对沙海蜇高生物量的营养供给来源进行了初步判断,并对比判断了不同大小的沙海蜇的食性或食物组成差异。基于Bayesian方法的稳定同位素混合模型SIAR(Stable isotope in R)的结果表明,沙海蜇倾向于摄食较小的生物(<1000μm),这些生物的食物贡献达到70%以上。沙海蜇虽然个体很大,但是主要仍摄食粒径较小的食物,包括小型桡足类和悬浮有机颗粒(POM)。脂肪酸的结果表明,沙海蜇的食物中含有陆源食物以及碎屑等。脂肪酸聚类结果显示,沙海蜇的脂肪酸组成与太平洋磷虾(Euphausia pacifica)等浮游磷虾、莹虾类相似度最高,两类生物可能存在食物竞争关系。我们初步判断,沙海蜇暴发主要会对小型浮游动物造成摄食压力。同时,沙海蜇可能会与磷虾等营养级别较低的消费者竞争,这种影响可能会沿食物网传播给营养级别较高的生物。

研究还发现,同月份采集的沙海蜇的食物组成并不因个体大小不同而产生差异。同时,由于浮游动物群落结构在不同月份会有变化,说明沙海蜇可获得的食物随时间会有种类变化。并且,沙海蜇生长过程中存在摄食器官的变化。基于以上两点,我们提出沙海蜇在开始漂浮到成熟期间,各类浮游生物对其食物贡献会发生变化的假设。

为了研究沙海蜇漂浮阶段的营养变化,在第三部分研究中,我们利用2018年渤海红沿河海域的四个调查航次,对5679四个月份的沙海蜇进行了采集,研究了其营养来源以及食物组成的变化。研究发现,不同月份沙海蜇的营养来源、食物组成和营养级的确存在差异。稳定同位素反映,沙海蜇水母体的营养级在5-7月呈下降趋势,其中6-7月下降明显。6-9月份POMδ13C值与沙海蜇δ13C值有明显的正相关关系,仅5月份关系不明显。5月份,沙海蜇与POMδ13C差值明显高于其他月份,结合脂肪酸结果,说明5月的沙海蜇与其他月份相比食物组成中肉食成分更多。SIAR模型结果揭示了各类食物对不同月份沙海蜇的贡献变化,结果显示尽管沙海蜇的个体随时间在不断长大,然而其摄食的食物中,小粒径的食物所占比重却逐渐升高。5-7月份,桡足类对沙海蜇的食物贡献逐渐减少,相对的,POM的贡献呈上升态势。7-9月份,各粒径动物对沙海蜇的食物贡献不再有明显变化。脂肪酸结果也显示,沙海蜇体内代表陆源营养和碎屑物质的脂肪酸C18:2n-6+C18:3n-3 C20:4n-6 值随时间发展均呈现上升趋势。在浮游动物丰度较高的5-6月份,沙海蜇脂肪酸构成中依然呈现升高的C18:2n-6+C18:3n-3 C20:4n-6 值。可见,陆源营养和碎屑可能是沙海蜇暴发的助推剂。

由于稳定同位素随着生物的生长同时会产生富集作用,而生物在不同生长阶段可能会伴有摄食器官的变化,另外不同月份的浮游动物群落结构也并不相同。因此,浮游动物群落的营养多样性存在动态变化。本研究利用Community-metrics 参数法研究了浮游动物群落的稳定同位素动态变化,对2018年红沿河海域浮游动物营养生态位以及营养多样性等进行了解析。结果显示,春末夏初的6月份浮游动物营养多样性最高,且群落占营养生态位空间最大。7月份沙海蜇大量生长,浮游动物群落所占营养生态位空间降至最小,浮游动物的营养多样性也达最小,说明7月份浮游动物群落可能受到沙海蜇爆发的影响最大,导致生物的营养多样性降低。

为了解水母食物组成是否存在种间差异,本研究第五部分重点研究了红沿河海域6种常见水母的食性和食物组成,并且与沙海蜇进行了对比。红沿河海域常见的大型水母除了沙海蜇外,还包括海月水母、白色霞水母,海蜇(Rhopilema esculentum)近几年较难采集到。常见小型水母包括卡玛拉水母(Malagazzia carolinae)、球形侧腕水母(Pleurobrachia globosa)、帽铃水母(Tiaricodon coerules)和半球杯水母(Clytia hemisphaerica)。研究表明,不同种类水母食物组成存在差异。常见水母的稳定同位素和脂肪酸标记物结果均表明,大型水母中,白色霞水母的食物组成中动物性食物占比例更高,高于海月水母和沙海蜇。小型水母(卡玛拉水母、球形侧腕水母、帽铃水母和半球杯水母)也对动物性食物摄食较多,多于大型水母中的沙海蜇和海月水母。其中半球杯水母和球形侧腕水母比白色霞水母摄食动物性食物更多。

在帽铃水母和半球杯水母的食物中,POM的食物贡献比例最少,大中型桡足类的食物贡献比例最高,高于小型桡足类。而另外两种小型水母卡玛拉水母和球形侧腕水母的各粒径食物贡献比例接近。在大型水母中,浮游动物对白色霞水母食物贡献最高,其次是海月水母,二者均高于沙海蜇。动物性食物在所有六种水母中所占比例均高于沙海蜇,仅沙海蜇的营养主要由POM提供,其他水母POM的食物贡献率均低于50%,其中最高为对海月水母的贡献率(45%)。六种水母暴发对浮游生态系统的影响方式与沙海蜇不同。沙海蜇的暴发主要会大量摄食<1mm的小型浮游生物和POM,对大中型浮游动物以及更高营养级生物(鱼类等)的影响更多可能是通过蜇伤以及饵料竞争导致的。海月水母对大中型浮游动物的摄食影响高于竞争。而帽铃水母和半球杯水母对大中型浮游动物的影响主要是摄食影响,它们的对大个体生物有较高的摄食压迫。白色霞水母以及小型水母中的球形侧腕水母和卡玛拉水母对各粒级的浮游动物均会有大量的摄食消耗,与帽铃水母和半球杯水母不同的是,它们对大型的甲壳动物也会有一定程度的摄食压迫。

Other Abstract

In the last two decades, jellyfish blooms are reported increasing in abundance and frequency around the world. The mass occurrence of jellyfish causes dramatic problems on food web due to their rapid population growth rate and feeding competitions. Jellyfish bloom also brings negative impacts on the marine economic development and marine ecosystem. The giant jellyfish Nemopilema nomurai widely distributes in Yellow Sea and Bohai Sea, which was frequently reported blooming in China. In this study, we investigated the diet and food composition of N. nomurai and their trophic level in plankton community by using the stable isotopes and fatty acid biomarkers. The aim of the study was to determine the food source of N. nomurai and its role in pelagic ecosystem, and to clarify its impact on the marine ecosystem.

First, we collected N. nomurai samples in Yellow Sea and East China Sea in August 2016 to analyze their characteristics of stable isotopes and fatty acids. We further analyzed the diets of N. nomurai, the contribution rate of various plankton, and whether the food compositions various with jellyfish size. The SIAR (Stable isotope in R, based on Bayesian method) results showed that N. nomurai tended to feed on the small organisms (<1000μm), which contributed more than 70% of the total diet. N. nomurai mainly consumes the small particle size food, including small copepods and pelagic organic materials (POM), which was independent of the size of N. nomurai. The results of fatty acids showed that N. nomurai diets contained land-sourced food and detritus. Fatty acid clustering results revealed that the fatty acid composition of N. nomurai was most similar to those of Euphausia pacifica and Lucifer intermedius, which implied that there might be food competition between them. According to our study, N. nomurai bloom will directly cause feeding pressure on small zooplankton. Meanwhile, N. nomurai may compete food with the consumers in low trophic levels, such as krill, and this effect may transfer to the higher trophic level organisms up the food web.

The study also found that the food composition of N. nomurai collected in the same month did not differ among different sized individuals. Since the zooplankton community structure differed among months, it meant that the food available to N. nomurai changed with time. Meanwhile, the feeding organs of N. nomurai change during their growth. Considering the above two points, we hypothesis that when the N. nomurai developed from ephyra to medusa stage, its food composition was different in different months.

To study that if the food composition changes with time, we collected N. nomurai samples in the areas adjacent the Hongyanhe river in the Bohai Sea during May, June, July and September 2018. The result revealed that N. nomurai's diet, food composition, and trophic level changed with time. The stable isotopes result showed that the trophic level of N. nomurai decreased from May to July. The reduction was significant from June to July. The δ13C value of POM from June to September was significantly positive correlation with the δ13C value of N. nomurai. In May, the difference between δ13C of N. nomurai and POM was significantly higher than that of other months. Combined with the fatty acid results, it indicated that N. nomurai ate more carnivorous food in May than in other months. The results of the SIAR model revealed that the contribution of small size food increased with time, which was independent of the size increasing of N. nomurai. From May to July, the food contribution of copepods decreased, while the contribution of POM increased. From July to September, the contributions of different sized food resource remained unchanged. The values of fatty acids C18:2n-6+C18:3n-3 and C20:4n-6, which represented land-derived food and detritus in N. nomurai, increased over time. In May and June when the abundance of zooplankton is relatively high, the C18:2n-6+C18:3n-3 and C20:4n-6 values in the N. nomurai fatty acid composition were still high. Therefore, land-derived food and detritus may be a potential booster for the outbreak of N. nomurai.

Stable isotopes would enrich with the growth of organisms. In some species, the morphological of feeding organ changes at different growth stages. In addition, the zooplankton community structure in different months was different. Therefore, there are dynamic changes in the trophic diversity of zooplankton community. In this study, the community-wide-metrics was used to analysis the dynamic changes of the trophic niche and trophic diversity of zooplankton community in the areas adjacent the Hongyanhe river in 2018. The results showed that the trophic diversity of zooplankton was highest in late spring and early summer, and the community occupied the largest trophic niche space. Then in July when the biomass of N. nomurai reached peak, the zooplankton community occupied the smallest trophic niche space, and its trophic diversity became minimized. It indicates that the zooplankton community could be threatened the most by the outbreaks of N. nomurai in July, leading to the reduction in the zooplankton trophic diversity.

To study if the food compositions are different from species to species, we investigated the diets of six jellyfish species in the areas adjacent the Hongyanhe river. Those jellyfish species were also compared with N. nomurai. In the study area, there are four giant jellyfish species including N. nomurai, A. aurita, C. nozakii and Rhopilema esculenta (which is rarely sampled in recent years). Common small jellyfish species include Malagazzia carolinae, Pleurobrachia globosa, Tiaricodon coerules and Clytia hemisphaerica. Results showed that there were differences in the food composition of each jellyfish species. In the giant jellyfishes, the composition of carnivorous food in C. nozakii was higher than that of A. aurita and N. nomurai. Small jellyfishes (M. carolinae, P. globosa, T. coerules, and C. hemisphaerica) were omnivorous and ate more carnivorous food than N. nomurai and A. aurita. Among them, C. hemisphaerica and P. globosa consumed more carnivorous food than C. nozakii.

To the food of T. coerules and C. hemisphaerica, POM contributed least, while large and medium-sized copepods contributed highest. The contribution rate of large and medium-size copepods was higher than that of small copepods. The other two small jellyfish M. carolinae and P. globosa shared similar food composition. In giant jellyfishes, large and medium-sized zooplankton contributed the most food for C. nozakii, followed by A. aurita, and finally the N. nomurai. The proportions of carnivorous food in the diets of N. nomurai were lowest among all the seven jellyfish species. The nutrition of N. nomurai was mainly provided by POM. The food contribution rate of POM in the other six jellyfish species was less than 50%. Among them, POM contributed highest to A. aurita with the ratio of 45%.

On the view of food composition, the outbreaks of N. nomurai will mainly ingest the organism smaller than 1mm. Their negative impacts on large and medium-size zooplankton and fishes were mainly by killing other organisms with their stinging tentacles and competing for the same resources. Impact of A. aurita on the large and medium-size zooplankton was more by feeding than competition. The effects of T. coerules and C. hemisphaerica on large and medium-size zooplankton were mainly by feeding. The bloom of C. nozakii, P. globosa and M. carolinae would cause feeding pressure on zooplankton of all sizes including large crustaceans.

MOST Discipline Catalogue理学 ; 理学::生态学
Language中文
Table of Contents

目录

第1章 研究现状和进展 1

1.1 水母类研究进展 1

1.1.1 水母的分类地位及分布 1

1.1.2 水母类特性 2

1.1.3 影响水母暴发的因素 3

1.2 沙海蜇的研究进展 4

1.2.1 沙海蜇概述 4

1.2.2 沙海蜇分布 5

1.2.3 沙海蜇特性 6

1.3 浮游动物概述 8

1.4 海洋生态系统生物营养来源的研究方法 9

1.4.1 肠道内含物法 9

1.4.2 稳定同位素法 10

1.4.3 脂肪酸标记物法 13

1.5 本研究拟解决的关键问题以及意义 16

第2章 黄东海沙海蜇的食性以及食物组成 18

2.1 前言 18

2.2 材料与方法 19

2.2.1 采样站位与采集方法 19

2.2.2 沙海蜇和浮游动物的丰度计算 20

2.2.3 脂肪酸样品处理与分析 21

2.2.4 稳定同位素样品的处理与分析 21

2.3 结果 23

2.3.1 沙海蜇以及浮游动物在黄东海的分布 23

2.3.2 沙海蜇的脂肪酸组成以及脂肪酸标志物 30

2.3.3 沙海蜇的食物组成 34

2.3.4 沙海蜇和浮游动物的稳定同位素分析 34

2.4 讨论 36

第3章 沙海蜇食物组成的月变化 39

3.1前言 39

3.2 材料与方法 40

3.2.1 采样站位与采集方法 40

3.2.2 脂肪酸样品处理与分析 40

3.2.3 稳定同位素样品处理与分析 41

3.3 结果 41

3.3.1 沙海蜇丰度与饵料丰度 41

3.3.2 沙海蜇脂肪酸构成变化 42

3.3.3 沙海蜇稳定同位素变化 47

3.4 讨论 49

第4章 沙海蜇与浮游食物网的营养关系 52

4.1 前言 52

4.2 方法 52

4.2.1 采样站位与采集方法 52

4.2.2 脂肪酸样品处理与分析方法 53

4.2.3 稳定同位素样品处理与分析方法 53

4.2.4 其他数据处理与分析 54

4.3 结果 54

4.3.1 2017年夏季浮游动物群落与多样性指数 54

4.3.2 2017年夏季沙海蜇与浮游动物群落的营养关系 59

4.3.3 2018年浮游动物群落与多样性指数 61

4.3.4 2018年沙海蜇与浮游动物群落的营养关系 66

4.3.5 2018年红沿河海域沙海蜇与浮游动物脂肪酸聚类分析 69

4.3.6 环境因子,沙海蜇分布对浮游动物群落的影响 73

4.4 讨论 76

4.4.1 群落同位素基线--悬浮颗粒有机物(POM)的变化 76

4.4.2 浮游食物网的营养关系 76

4.4.3 浮游生物群落参数的变化 78

第5章 红沿河海域常见水母的食物组成以及与浮游食物网的营养关系 79

5.1 前言 79

5.2 材料与方法 79

5.2.1 样品采集 79

5.2.2 脂肪酸样品处理与分析 80

5.2.3 稳定同位素样品处理与分析 81

5.3 结果 81

5.3.1 红沿河海域常见水母的脂肪酸组成 81

5.3.2 红沿河海域常见水母的稳定同位素 87

5.4 讨论 95

5.4.1 红沿河海域常见水母的食物来源 95

5.4.2 红沿河海域各饵料生物对水母的食物贡献率 97

第6章 结论与展望 99

6.1 主要研究结论 99

6.2 本文的创新点 100

6.3 展望 100

参考文献 103

致 谢 121

作者简历及攻读学位期间发表的学术论文与研究成果 123

Document Type学位论文
Identifierhttp://ir.qdio.ac.cn/handle/337002/164793
Collection海洋生态与环境科学重点实验室
Recommended Citation
GB/T 7714
王俊健. 我国近海水母沙海蜇的食物组成以及其与浮游动物群落的营养关系[D]. 中国科学院海洋研究所. 中国科学院大学,2020.
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