Abstract:

The frequency of algal blooms triggered by eutrophication is increasing in plateau wetland ecosystems, which negatively affects the health of local ecosystems. To analyze the changes of plankton community structures during the whole process of Cyanobacterial bloom, the Haihu wetland in Xining City, Qinghai Province was investigated as a study area. Plankton community structures were monitored at six monitoring sites in March (bloom outbreak stage), April (bloom decline stage) and May (bloom end stage) in 2022. Vegan and rdacca.hp packages of the R were utilized to quantitatively analyze the environmental factors that affect the structures of the plankton communities. Results showed that: 1) a total of 94 species of 7 phyla of phytoplankton and 46 species of 4 phyla of zooplankton were identified in the above three periods. Keratella cochlearis was the dominant species in all three periods. 2) An increasing trend from upstream to downstream was observed in plankton density and biomass. The trends of phytoplankton and zooplankton exhibited contrasting patterns. The phytoplankton biomass reached the maximum value (63.84 mg·L⁻¹) in bloom decline stage, while the zooplankton biomass reached its maximum value (6.76 mg·L⁻¹) in bloom end stage. 3) Pearson Correlation and Canonical Correspondence Analysis (CCA) showed significant differences in dominant influencing factors of the dominant plankton species in three periods of algal bloom. Phytoplankton and zooplankton were significantly affected by TN and water temperature in the bloom outbreak stage (p<0.05), NH₄⁺-N and TP in the bloom decline stage (p<0.05), and pH and water temperature in the bloom end stage (p<0.05), respectively. 4) The water quality evaluation based on the zooplankton diversity index indicated that the water quality of the Haihu wetland was at a good level between medium pollution and no pollution. 5) Variance Partitioning Analysis (VPA) and Hierarchical Partitioning (HP) showed that water temperature produced stronger effect (13.01%) on phytoplankton community (p<0.01), while TN conducted stronger effect (6.70%) on zooplankton community structures (p>0.01). This study showed that the Cyanobacterial bloom significantly affected the succession of plankton community structures in the Haihu wetland, which may provide some information for the management of wetland algal blooms.

Key words: hierarchical partitioning, phytoplankton, zooplankton, canonical correspondence analysis (CCA), Qinghai Plateau, eutrophication

摘要：

由于水体富营养化引发的水华在高原湿地生态系统的暴发频率日益增加，对当地生态系统健康产生负面的影响。为分析蓝藻水华及其生消全过程中浮游生物群落结构变化特征，以青海省西宁市海湖湿地为研究区，于2022年3月（水华暴发期）、4月（水华衰退期）和5月（水华结束期）对6处监测点的浮游生物群落开展调查，通过R软件的Vegan包和rdacca.hp包对影响浮游生物群落结构的环境因子进行定量分析。结果表明，1）3个时期共鉴定出浮游植物7门94种、浮游动物4门46种；螺形龟甲轮虫（Keratella cochlearis）在3个时期均为优势动物。2）浮游生物密度和生物量呈现由上游向下游增加的趋势；浮游植物和浮游动物呈现相反的变化趋势，浮游植物生物量在衰退期达到最大值（63.84 mg·L⁻¹），而浮游动物生物量在结束期达到最大（6.76 mg·L⁻¹）。3）Pearson相关性和典范对应分析（CCA）结果显示，浮游生物优势种在水华不同时期的主要影响因素存在差异，浮游植物和浮游动物在暴发期分别受TN和水温的影响显著（p<0.05），在衰退期分别受NH₄⁺-N和TP的影响显著（p<0.05），而在结束期分别受pH和水温的影响显著（p<0.05）。4）基于浮游动物多样性指数的水质评价结果显示，海湖湿地水体介于中污与无污之间，水质状态表现为良好。5）变差分解（VPA）和层次分割（HP）分析发现，水温对浮游植物群落结构的影响最大（13.01%）（p<0.01），而TN对浮游动物群落结构的影响最大（6.70%）（p>0.01）。该研究表明，蓝藻水华显著影响海湖湿地浮游生物群落结构的演替。研究结果对利用环境手段进行水华治理具有重要意义。

关键词: 层次分割, 浮游植物, 浮游动物, CCA分析, 青藏高原, 富营养化