Ecological factors and phytoplankton community structure in Xiquanyan Reservoir,Harbin,P.R.China

Abstract

西泉眼水库作为哈尔滨市第二水源地,事关居民的饮用水安全,而浮游植物群落特征则是水库生态系统健康状况监测与评估的重要研究内容之一,能为水库生态系统健康提供科学支撑.本研究设置13个采样点,对库区和入库河流的浮游植物群落进行对比分析,采样时间为蓝藻水华易发的7月和8月.经镜检,共鉴定浮游植物7门169种,其中绿藻门最多,83种,占总种数的49.11%;硅藻门次之,47种,占总种数的27.81%;蓝藻门15种,占总种数的8.88%;隐藻门最少,仅有2种.浮游植物丰度在10.92×10⁵～88.44×10⁵cells/L之间,均值为51.6×10⁵cells/L,以8月的3^#采样点最高;生物量在2.61～22.44mg/L之间,均值为10.37mg/L,以8月的5^#采样点最高.Shannon-Wiener指数在2.46～4.69之间,均值为3.33,以7月12^#采样点最高.研究水域浮游植物优势种群以梅尼小环藻(Cyclotella meneghiniana)、肘状针杆藻(Synedra ulna)、阿氏席藻(Phormidium allorgei)和游丝藻(Planctonema sp.)为主.同时,典范对应分析表明:1)既将西泉眼水库库区和入库河流区分为两个相对独立的生态系统,又展现了同一生态系统内的月份变化趋势,说明西泉眼水库库区和入库河流区的浮游植物群落的时空分布异质性显著;2)库区内河流入库口处、库心和大坝口处浮游植物群落梯级差异显著,入库河流区水质明显优于库区;3)氨氮、硝态氮、总氮和总磷是影响浮游植物种群的主要驱动因子.研究认为,西泉眼水库水体总体上已处于中度富营养水平,并存在进一步富营养化的风险.建议水库管理部门建立水生态系统健康监测与评估预警体系,配套相应的水生态管理制度,并采取适宜的生态修复技术等生态治理措施,以确保哈尔滨市供水水源安全.;Xiquanyan Reservoir, as the second water source place of Harbin, whose water ecosystem's state of health needs to be monitored effectively. In this study, the reservoir and upper rivers were sampled at 13 points, 9 of which were in the reservoir area and the others in the inflow-river area. In July and August of 2010, the phytoplankton were both qualitative and quantitative studied, along with the investigation on the water environmental factors. The results showed that, in total,7 phyla 169 species were identified, the majority of which were Chlorphyta(83 species), Bacillaroiphyta(47 species) and Cyanophyta(15 species). The others were listed as Euglenophyta(12 species), Chrysophyta(6 species), Pyrrophyta(4 species) and Cryptophyta(2 species). In summer, the phytoplankton abundance and biomass were 10.92×10⁵-88.44×10⁵ cells/L(the mean value is 51.6×10⁵ cells/L) and 2.61-22.44mg/L(the mean value is 10.37mg/L), respectively. The Shannon-Wiener index was between 2.46-4.69 with the mean value of 3.33. Moreover, Cyclotella meneghiniana, Synedra ulna, Phormidium allorgei and Planctonema sp. were the key dominant species in summer.Canonical correspondence analysis was used to analysis the phytoplankton community structure and their relationship with environmental factors. The results showed that, 1) The phytoplankton community in different sampling sites reflected significant spatial and temporal heterogeneity; 2) The estuary area, lake central district and the dam area were of significant difference, and the river water quality was significantly better than that in reservoir area; 3) Ammonia, nitrate, total nitrogen and total phosphorus were the main driving factors of phytoplankton populations. This study suggested that, the Xiquanyan Reservoir water body has been in moderate eutrophication level, and there is a risk of further eutrophication. Therefore, we proposed reservoir management departments to establish the system of ecosystem health monitoring, assessing and early-warning, to ensure the safety of Harbin water supply.