Abstract:

To understand the role of phytoplankton functional groups in the aquatic environment and the status of aquatic ecology in the Guizhou Plateau, phytoplankton and water quality surveys were conducted in March (dry season) and August (wet season) in 2020, 2021, and 2022, using the Chetian River in Guiyang City as an example. The concept of functional groups was used to divide phytoplankton in the Chetian River, and the spatiotemporal successional characteristics of the functional phytoplankton groups were explored. Redundancy analysis (RDA) was used to identify the main environmental factors in different hydrological periods, and the relationship between functional phytoplankton groups and their adapted habitats was revealed. The Shannon-Wiener diversity index and Q_r index were used to evaluate the water quality and environment. The results showed the following. 1) A total of 70 phyla and 70 species were identified in the Chetian River, and the phytoplankton community structure was generally of the green algae-diatom-cyanobacteria type, accounting for 42.9%, 27.1%, and 18.6%, respectively, and the abundance of phytoplankton varied in the range of 1.86×10⁴-1.28×10⁷ cells∙L⁻¹, with a mean value of 1.76×10⁶ cells∙L⁻¹, and the biomass varied in the range of 0.09-336.3 mg∙L⁻¹, with a mean value was 28.9 mg∙L⁻¹. The dominant species of phytoplankton in the lakes were Cyclotella sp., Pseudoanabaena limnetica, and Cryptomonas sp. 2) Phytoplankton can be categorized into 23 functional groups, the dominant of which are B, S1, and Y. There were significant temporal and spatial differences in the composition of functional groups, and the successional sequence was B/S1 in the dry season→LM/B/H1 in the wet season and LM in the reservoir section→MP/Y in the stream section, reflecting the characteristics of aquatic environments with variable habitats and high productivity. Among these, WT, TN, and COD_Mn were the most important environmental variables influencing the spatiotemporal distribution patterns of the phytoplankton functional groups. 3) The suitable habitat of phytoplankton functional groups showed that the Chetian River was in a moderate to eutrophic condition. The Shannon index (H) was 1.4 in the dry season and 1.7 in the wet season, which belonged to the α-moderate pollution type, and the ecological state index was 3.1 in the dry season and 2.9 in the wet season, indicating that the environment was “good-moderate”. Compared with the diversity index, the Q_r index quality assessment method based on functional group classification is more suitable for the water body of the Chetian River in the Guizhou Plateau. The research results can provide a scientific basis for protecting the ecological environment of the river water in the Guizhou Plateau.

Key words: plateau rivers, phytoplankton, functional groups, spatiotemporal succession, water quality evaluation

摘要：

为了解浮游植物功能群对贵州高原水环境的指示作用和水生态现状，以贵阳市车田河为例，于2020、2021、2022年的3月（枯水期）和8月（丰水期）对浮游植物和水质环境展开调查。利用功能群的概念对车田河浮游植物进行划分，探究浮游植物功能群时空演替特征，运用冗余分析方法（Redundancy analysis，RDA）识别不同水文期下的主要环境驱动因子，揭示浮游植物功能群与其适应生境之间的相互关系；采用Shannon-Wiener多样性指数和Q_r指数对水质环境进行评价。结果表明，1）车田河共鉴定出7门70种，浮游植物群落结构总体呈绿藻-硅藻-蓝藻型，占比分别为42.9%、27.1%、18.6%，浮游植物丰度变化范围为1.86×10⁴—1.28×10⁷ cells∙L⁻¹，均值为1.76×10⁶ cells∙L⁻¹，生物量变化范围为0.09—336.3 mg∙L⁻¹，均值为28.9 mg∙L⁻¹；浮游植物优势种主要为小环藻（Cyclotella sp.）、湖泊假鱼腥藻（Pseudanabaena limnetica）和隐藻（Crytomonas sp.）等。2）浮游植物共可归类为23个功能群，其中共同优势功能群为B、S1、Y类型，功能群的组成存在显著时空差异，演替序列表现为枯水期B/S1→丰水期LM/B/H1，水库断面LM→溪流断面MP/Y，反映出生境多变、生产力旺盛的水环境特征。其中，WT、TN和COD_Mn是影响浮游植物功能群时空分布格局的主要环境变量。3）浮游植物功能群适宜生境指示车田河为中到富营养状态，香农指数（H）枯水期为1.4、丰水期为1.7，属于α-中污型，生态状态指数枯水期为3.1、丰水期为2.9，指示环境为“好—中等”。相对于多样性指数，基于功能群分类的Q_r指数质量评价方法更适用于贵州高原车田河水体，研究结果可为贵州高原河流水生态环境保护提供科学依据。

关键词: 高原河流, 浮游植物, 功能群, 时空演替, 水质评价