丰水期珠江口浮游植物群落结构特征及其环境影响因子分析

Phytoplankton community composition and its environmental impact factors in Pearl River Estuary during wet season

  • 摘要: 珠江口海域生态环境问题日益突出。浮游植物是评价水质、生态功能等的重要参考指标,可为该海域生态环境保护与治理提供科学依据。为了更全面地了解丰水期珠江口海域浮游植物的分布特征及环境状况,根据2020年9月和2021年5月珠江口海域浮游植物调查数据,分析了该海域丰水期浮游植物的群落结构特征及其环境影响因子。共鉴定浮游植物7门56属102种,其中硅藻种类最多 (69种),占67.65%,甲藻次之(17种),占16.67%。浮游植物丰度水平2021年5月 (1191.86×104个·m−3)高于2020年9月(103.64×104个·m−3),丰度组成均以硅藻为主,其次为蓝藻或甲藻;多样性指数和均匀度指数2021年5月(2.08和0.49)高于2020年9月 (1.65和0.41),两者均相对较低。非度量多维尺度分析 (Non-metric multidimensional scaling, NMDS) 结果显示该海域浮游植物以S8采样点为界,分为南、北2个群落;浮游植物优势种2020年9月主要为咸淡水种颗粒直链藻 (Melosira granulata) 和广盐性沿岸种假微型海链藻 (Thalassiosira pseudonana),2021年5月主要为耐盐性沿岸种短角弯角藻 (Eucampis zodiacus)。冗余分析 (Redundancy analysis, RDA) 显示影响珠江口海域浮游植物群落结构特征的环境因子主要为氮 (N)、磷 (P)、氮磷比 (N/P)、硅酸盐 (SiO3 2−)、pH和盐度。丰水期冲淡水强度对珠江口海域浮游植物种类组成、丰度分布和多样性等均有很大的影响。

     

    Abstract: The ecological environment of the Pearl River Estuary has become increasingly prominent. Phytoplankton is an important reference index for evaluating water quality, ecological functions, etc., which can provide a scientific basis for the protection and management of the ecological environment of this sea area. In order to better understand the distribution characteristics and environmental conditions of phytoplankton in the Pearl River Estuary during wet season, we analyzed the phytoplankton community structure characteristics and its environmental impact factors in the Pearl River Estuary during wet season, based on the phytoplankton survey data collected in this sea area in September 2020 and May 2021. A total of 102 species of phytoplankton belonging to 56 genera and 7 phyla were identified, among which diatom species (69 species) accounted for 67.65%, and dinoflagellate species (17 species) accounted for 16.67%. The abundance level in May 2021 (1191.86×104 cells·m−3) was higher than that in September 2020 (103.64×104 cells·m−3), and the abundance composition was mainly diatoms, followed by cyanobacteria or dinoflagellate. The diversity index and evenness index in May 2021 (2.08, 0.49) were higher than those in September 2020 (1.65, 0.41), both of which were relatively low. NMDS analysis shows that the phytoplankton community in this sea area can be divided into two groups, north and south, with S8 as the boundary. The dominant species were Melosira granulata (Brackish water species) and Thalassiosira pseudonana (Euryhaline coastal seawater species) in September 2020, while Eucampis zodiacus (salt-tolerant coastal species) in May 2021. Redundancy analysis (RDA) shows that nitrogen, phosphorus, nitrogen to phosphorus ratio, silicate, pH and salinity were the main environmental factors affecting phytoplankton community in the Pearl River Estuary. The intensity of dilute water in wet season has a great impact on the species composition, abundance distribution and diversity of phytoplankton in the Pearl River Estuary.

     

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