| 大亚湾夏季浮游植物群落结构及对淡澳河输入的响应特征* |
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| 引用本文： | 张立明,谭烨辉,李佳俊,黄小平,刘甲星.大亚湾夏季浮游植物群落结构及对淡澳河输入的响应特征*[J].热带海洋学报,2020,39(5):43-54. |
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| 作者姓名： | 张立明 谭烨辉 李佳俊 黄小平 刘甲星 |
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| 作者单位： | 1.中国科学院热带海洋生物资源与生态重点实验室, 中国科学院南海海洋研究所, 广东 广州 5103012.中国科学院大学, 北京 1000493.中国水产科学研究院南海水产研究所, 广东 广州 510300 |
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| 基金项目： | 国家自然科学基金项目(31971432);国家自然科学基金项目(41506161);南方海洋科学与工程广东省实验室(广州)项目(GML2019ZD0405);广东省科技计划项目(2017B0303014052);广东省海洋经济促进项目基金(GDOE2019A32) |
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| 摘 要： | 浮游植物是水生生态系统的基础生产者, 其群落结构直接影响到生态系统的健康和安全。河流输入是人类活动影响大亚湾水体环境最重要的途径之一, 淡水输入改变了水体温度、盐度、浊度和营养盐等环境因子, 对浮游植物群落结构产生影响。文章调查研究了2015年河流输入最强的夏季丰水期大亚湾的水体环境因子和浮游植物群落结构, 分析了在较强河流输入影响下浮游植物群落结构的动态变化及其对环境因子的响应。结果发现, 夏季大亚湾淡澳河的输入使湾顶淡澳河口区域形成层化的低盐、高温、低透明度、高营养盐的水体, 湾中部表层水体则受一定强度河流羽流影响, 而湾口和湾中部底层水体主要受外海水影响。淡澳河淡水输入是夏季大亚湾外源性氮、磷营养盐的主要来源, 而硅酸盐除河流输入外, 外海水也输入较多的营养盐使得底层水体硅酸盐浓度较高。夏季大亚湾水体营养比例失衡较严重, 溶解无机磷是限制浮游植物生长的重要因子。硅藻是大亚湾夏季浮游植物的优势类群, 调查发现3种优势种极小海链藻(Thalassiosira minima)、中肋骨条藻(Skeletonema costatum)和圆海链藻(Thalassiosira rotula)]均为硅藻。通过聚类分析, 可将大亚湾夏季浮游植物群落主要分为3种类型, 分别为: 浮游植物丰度较大的极小海链藻藻华暴发的群落, 位于淡澳河口, 受河流输入影响明显; 中肋骨条藻占据优势的群落, 分布在受一定强度的河流及其羽流影响的湾顶和湾中部区域; 浮游植物丰度较低的群落, 无明显优势种, 主要分布在湾口海水影响区域。淡澳河口的水体环境有利于小型链状硅藻极小海链藻的快速繁殖并暴发了藻华, 藻华发生时的海水环境条件为: 温度30~31°C, 盐度17‰~31‰, 水体透明度0.45~1.2m。硅藻对不同营养盐利用的差异以及随后的生物碎屑和颗粒沉降过程导致藻华发生区域Si∶N值略降低, N∶P值显著升高。河流输入影响下, 单一物种大量生长使得浮游植物群落种类组成丰度分布极不均匀, 从而导致淡澳河口浮游植物群落的种类多样性和均匀度指数降低, 种类多样性和均匀度指数均从淡澳河口向湾口逐渐增大。
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| 关 键 词： | 大亚湾 浮游植物 河流输入 群落结构 营养盐结构 |
| 收稿时间： | 2020-01-21 |
| 修稿时间： | 2020-03-30 |
Characteristics of the phytoplankton community and its response to Dan’ao River input in Daya Bay in summer* |
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| ZHANG Liming,TAN Yehui,LI Jiajun,HUANG Xiaoping,LIU Jiaxing.Characteristics of the phytoplankton community and its response to Dan’ao River input in Daya Bay in summer*[J].Journal of Tropical Oceanography,2020,39(5):43-54. |
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| Authors: | ZHANG Liming TAN Yehui LI Jiajun HUANG Xiaoping LIU Jiaxing |
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| Institution: | 1. Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China2. University of Chinese Academy of Sciences, Beijing 100049, China3. South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510300, China |
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| Abstract: | Phytoplankton are the primary producer of aquatic ecosystem, and their community structure directly affects the health and safety of aquatic ecosystem. River input is one of the most important impacts reflecting the human activities on Daya Bay waters, which influences the phytoplankton community structure by changing environmental factors such as temperature, salinity, turbidity, nutrients, and so on. We investigated water environmental factors and phytoplankton community structure in Daya Bay in the summer of 2015 when large amount of river input happened. The dynamic change of phytoplankton community structure under the influence of the strong river input and its response to environmental factors were analyzed. The results showed that stratified waters with low salinity, high temperature, declined transparency, and enhanced nutrient concentrations formed at the Dan’ao River Mouth due to river input, while the waters in the middle and opening of Daya Bay were greatly affected by seawater intrusion. Freshwater input was the main external source of nitrogen and phosphorus nutrients in Daya Bay, and both freshwater input and invasive seawater were both important source of silicate. Nutrient structure was highly imbalanced in Daya Bay in summer, and dissolved inorganic phosphorus was the important limited factor of the growth of phytoplankton. Diatoms were the dominant group of phytoplankton in Daya Bay in summer 2015, and three dominant species included Thalassiosira minima, Skeletonema costatum and Thalassiosira rotula were identified. Cluster analysis showed that phytoplankton community in Daya Bay in summer 2015 could be mainly divided into three types. Type Ⅰ: Algae assemblage occurred at the Dan’ao River Mouth with high abundance of phytoplankton and bloom of Thalassiosira minima under influence of freshwater discharge; Type Ⅱ: algae assemblage dominated by Skeletonema costatum observed at the top and middle Daya Bay under subordinate influence of river plume; Type Ⅲ: algae assemblage with low phytoplankton abundance and no obvious dominant species mainly occurred in the opening of Daya Bay under the influence of sea water. The water environments at the Dan’ao River Mouth were beneficial to the growth and bloom of tiny chain-formed Thalassiosira minima, and the bloom occurred in the environmental gradient of temperature 30 ~ 31 °C, salinity 17 ‰ ~ 31 ‰ and water transparency 0.45 ~ 1.2 m. The difference in the utilization of different nutrients by diatoms and the subsequent settlement of biogenic detritus and particles resulted in a slight decrease of Si∶N ratio and a significant increase of N∶P ratio in the area where algae bloomed. The distribution of phytoplankton abundance was extremely uneven at the Dan’ao River Mouth due to the bloom of single species under the influence of freshwater discharge, which led to the decrease of Shannon-Wiener index and Pielou’s evenness index. The two indexes both increased from the Dan’ao River Mouth to the opening of Daya Bay. |
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| Keywords: | Daya Bay phytoplankton river input community structure nutrients structure |
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