海洋生态与环境科学重点实验室知识库

绿潮是一种由大型绿藻脱离固着基形成漂浮群体后，快速增殖或聚集导致的海洋生态灾害。自2007年起，每年的4-7月中国南黄海都会暴发大规模的绿潮。绿潮的暴发严重影响了当地的旅游业和养殖业等，年均损失超过10亿元。绿潮发生期间对海洋环境带来许多影响，其中包括遮蔽海面、改变海水营养结构以及堆积腐烂造成缺氧。浮游生物作为海洋生态系统中的重要组成部分，对环境因子的改变十分敏感。为了了解绿潮发生期间浮游生物群落结构特征以及相互关系，本文在2022年及2023年7月初南黄海绿潮发生区域（119°E ~ 122.5°E，34.5°N ~ 37°N），设置26个站位并采集样本，提取表层海水eDNA并进行高通量测序获得主要浮游植物、浮游动物和浮游细菌的种群信息。利用统计分析方法，分析了各浮游生物群落结构与浒苔生物量、环境因子以及相互关系，得到以下结果：

1. 根据现场调查，2022年7月南黄海调查区域浒苔分布范围为海州湾至烟台的近岸海域，生物量为1.81 t/km²，2023年同期浒苔分布位于海州湾至青岛海域，生物量为3.28 t/km²，2023年绿潮规模更大，生物量为2022年的2倍；
2. 浒苔覆盖区浮游植物群落多样性更低，丰富度更高。2023年浮游植物丰富度大于2022年，2023年浮游植物优势种甲藻在群落中的占比高于2022年，表现为物种趋于单一化；
3. 浒苔覆盖区与无浒苔覆盖区微型浮游动物的群落结构显著不同，浒苔潮覆盖区物种丰富度高于无浒苔覆盖区。浮游动物群落优势种为桡足类，2023年浮游动物优势种桡足类占比低于2022年，且表现为桡足类占比与浒苔生物量呈负相关关系，水螅纲水母占比与浒苔生物量呈正相关关系，优势种发生更替；
4. 2023年浒苔覆盖区与无浒苔覆盖区浮游细菌群落结构有显著性差异，而2022年没有显著性差异。2023年浮游细菌丰富度大于2022年，2023年浮游细菌优势种γ-变形菌在群落中的占比高于2022年，浮游细菌群落多样性降低，物种趋于单一化趋势；
5. 通过浮游生物共现网络分析发现，2022年及2023年浒苔覆盖区浮游生物群落的相互作用均表现为正相关关系大于负相关关系，这有可能是在极端条件下，生物避免竞争所带来的能量消耗。2023年浮游生物间正相互作用强于2022年，存在绿潮的暴发会使得群落间正相互作用加强的可能性。浮游生物群落与环境中的各营养物质有着显著的相关性，不同年份影响浮游生物的环境因子存在差异；

综上所述绿潮的暴发能影响浮游植物、浮游动物以及浮游细菌群落组成及结构。绿潮发生期间浮游生物存在相互作用且趋向于正相关关系。绿潮的发生会对浮游生物群落造成物种单一化、优势种更替以及引发次生灾害等潜在影响。基于以上研究，为探究绿潮的暴发对海洋生态系统的影响提供基础数据。

Green tide is a marine ecological disaster wich is caused by the rapid growth or aggregation of large green algae. Those large green algae detach from their fixed base and form a floating population. Since 2007, a large-scale green tide has erupted in the Southern Yellow Sea of China every April to July. The outbreak of the green tide has seriously affected the local tourism and aquaculture industry, with annual losses exceeding one billion yuan. The occurrence of green tide has many impacts on the marine environment, including shading the sea surface, altering the nutrient structure of seawater, and causing a lack of oxygen. Planktonic organisms as an important component of marine ecosystems, are highly sensitive to changes in environmental factors. In order to understand the structural characteristics and interrelationships of plankton communities during the occurrence of green tide, this study investigated 26 stations and collected samples green tide occurrence areas (119°E ~ 122.5°E,34.5°N ~ 37°N) in the Southernern Yellow Sea in early July 2022 and 2023. Surface seawater eDNA was extracted and high-throughput sequencing was performed to obtain the information of phytoplankton, zooplankton, and bacterioplankton. Using statistical analysis methods th analyzed the relationship between the structure of plankton communities and the biomass of Ulva prolifera, environmental factors. The following results were obtained:

1. In July 2022, the distribution range of Ulva prolifera in the Southern Yellow Sea survey area was the nearshore sea area from Haizhou Bay to Yantai, with a biomass of 1.81 t/km². During the same period in 2023, Ulva prolifera was distributed in the sea area from Haizhou Bay to Qingdao, with a biomass of 3.28 t/km². In 2023, the scale of the green tide was larger. The biomass in 2023 was twice that in 2022;

       2. The phytoplankton communities in areas covered byUlva prolifera had a lower diversity and higher richness. The richness of phytoplankton in 2023 was higher than that in 2022. The proportion of dinophyta in 2023 was higher than in 2022, indicating a trend towards species homogenization;

3. The zooplankton community structure in the area coverd by Ulva prolifera was different from that in the area without Ulva prolifera. The species richness in areas covered by Ulva prolifera was higher than that in areas without Ulva prolifera. The dominant species of zooplanktonic communities were copepods, in 2023 was lower than that in 2022, and it was shown that the proportion of copepods was negatively correlated with the biomass of Ulva prolifera. The proportion of jellyfish in the order Hydra was positively correlated with the biomass of Ulva prolifera, and the dominant species may were replaced；
4. In 2023 the bacterioplankton community structure in the area coverd by Ulva prolifera was different from that in the area without Ulva prolifera, but this phenomenon was not found in 2022. The richness of bacterioplankton in 2023 was highter than that in 2022, in 2023, Gammaproteobacteria is the dominant species of bacterioplankton. The proportion of Gammaproteobacteria in 2023 was higher than in 2022, and the diversity of bacterioplankton communities is decreasing, with species tending towards singularity;
5. Through the analysis of planktonic collinearity network, it was found that the interactions between planktonic communities in the areas covered by Ulva prolifera in 2022 and 2023 were positively correlated rather than negatively correlated. This is due to the energy consumption caused by avoiding competition among organisms under extreme conditions. The positive interaction between plankton in 2023 was stronger than in 2022, and there was a possibility that the outbreak of green tide will strengthen the positive interaction between communities. There was a significant correlation between plankton communities and various nutrients in the environment, but there are differences in the environmental factors which can affect plankton in different years;

In summary, the outbreak of green tide can affect the composition and structure of phytoplankton, zooplankton, and bacterioplankton. During the green tide, plankton interacted with each other and tended to have a positive correlation. The occurrence of green tide have potential impacts on plankton communities, such as species homogenization, dominant species replacement, and secondary disasters. Based on the above research, provide basic data for exploring the impact of green tide outbreaks on marine ecosystems.

第1章 绪论... 1

1.1 浒苔绿潮概述... 1

1.2 绿潮发生与浮游生物关系的研究现状... 2

1.2.1 绿潮发生与浮游植物关系的研究现状... 2

1.2.2 绿潮发生与浮游动物关系的研究现状... 3

1.2.3 绿潮发生与浮游细菌关系的研究现状... 4

1.3 浮游生物群落研究方法... 5

1.3.1 利用镜检方法识别浮游生物种类... 5

1.3.2 利用分子生物学方法识别浮游生物种类... 5

1.4 生物共现网络方法分析浮游生物之间关系... 6

1.5 研究内容及意义... 7

第2章 2022年及2023年南黄海绿潮分布及环境特征... 9

2.1 前言... 9

2.2 材料与方法... 9

2.2.1 航次时间与站位... 9

2.2.2 漂浮藻类采集及生物量分析... 10

2.2.3 环境数据获取... 10

2.3 结果... 10

2.3.1 2022及2023年南黄海绿潮分布与生物量... 10

2.3.2 2022及2023年南黄海环境特征... 11

2.4 讨论... 13

2.5 小结... 14

第3章 南黄海绿潮发生期间浮游植物群落结构特征... 15

3.1 前言... 15

3.2 材料与方法... 16

3.2.1 浮游植物样品采集... 16

3.2.2 浮游植物DNA提取及测序分析... 16

3.2.3 数据统计分析... 16

3.3 结果... 17

3.3.1 南黄海绿潮发生期间浮游植物群落结构特征... 17

3.3.2 浒苔覆盖区UCR及无浒苔覆盖区NUCR浮游植物群落结构比较... 18

3.3.3 浒苔生物量与浮游植物相对丰度相关性分析... 20

3.4 讨论... 22

3.5 小结... 22

第4章 南黄海绿潮发生期间浮游动物群落结构特征... 25

4.1 前言... 25

4.2 材料与方法... 25

4.2.1 浮游动物定性样品采集... 25

4.2.2 浮游动物DNA提取及测序分析... 26

4.2.3 2023年浮游动物定量样品采集与计数... 26

4.2.4 数据统计与分析... 26

4.3 结果... 26

4.3.1 南黄海绿潮发生期间浮游动物群落结构特征... 26

4.3.2 浒苔覆盖区UCR及无浒苔覆盖区NUCR浮游动物群落结构比较... 29

4.3.3 浒苔生物量与浮游动物相对丰度相关性分析... 31

4.4 讨论... 33

4.5 小结... 35

第5章 南黄海绿潮发生期间浮游细菌群落结构特征... 37

5.1 前言... 37

5.2 材料与方法... 37

5.2.1 浮游细菌定性样品采集... 37

5.2.2 浮游细菌DNA提取以及测序分析... 38

5.2.3 2023年浮游细菌定量样品采集及计数... 38

5.2.4 数据分析与统计... 39

5.3 结果... 39

5.3.1 南黄海绿潮发生期间浮游细菌群落结构特征... 39

5.3.2 浒苔覆盖区UCR及无浒苔覆盖区NUCR浮游细菌群落结构比较... 41

5.3.3 浒苔生物量与浮游细菌相对丰度相关性分析... 43

5.4 讨论... 44

5.5 小结... 46

第6章 浮游生物相互作用与浒苔生物量相关性分析... 47

6.1 前言... 47

6.2 浮游生物共现网络图的绘制... 47

6.3 结果... 48

6.3.1 南黄海绿潮发生期间浮游生物间相互作用... 48

6.3.2 浮游生物多样性及浒苔生物量与环境因子相关关系... 51

6.4 讨论... 54

6.5 小结... 54

第7章 小结、结论与展望... 55

7.1 小结... 55

7.2 结论... 55

7.3 不足与展望... 55

参考文献... 57

致谢... 73

作者简历及攻读学位期间发表的学术论文与其他相关学术成果... 75