庐山西海夏秋季浮游植物群落结构及多样性分析

为了解庐山西海生态系统结构,维护水库生态系统平衡,于2012年夏季(8月)和秋季(10月)在庐山西海均匀设置18个采样点,对浮游植物进行采样调查。结果表明,浮游植物共计8门、86种;其中,绿藻门种类最多,共43种,占总种类的59.43%;其次是硅藻门和蓝藻门,为17种和14种,分别占19.54%和16.09%。优势种共4门、14种,主要有莱哈衣藻(Chlamydomonas reinhardi)、黏四集藻(Palmellaceae mucosa)、类颤藻鱼腥藻(Anabaena oscillarioides)、卵形隐藻(Cryptomonas ovate)和尖尾蓝隐藻(Chroomonas acuta)。浮游植物密度为4.28×105~5.17×106个/L,平均为2.20×106个/L;生物量为1.24~7.01 mg/L,平均为2.90 mg/L;其中,夏季平均密度为3.15×106个/L,生物量平均为3.90 mg/L;而秋季平均密度为1.25×106个/L,生物量平均为1.89 mg/L。Shannon-Wiener多样性指数为2.84~4.45,Pielous均匀度指数为0.63~0.89,Margalef丰富度指数为1.46~3.69。庐山西海浮游植物的季节性变化明显,藻类种数、数量和生物量均表现为夏季高于秋季,生物多样性指数表现为秋季大于夏季;空间分布上,夏、秋季各采样点浮游植物的种类丰富程度、群体结构稳定程度及水质清洁程度总体较好,其中夏季过渡区较好,而秋季湖泊区较好。

Phytoplankton Community Structure and Biodiversity at Lushanxihai Reservoir in Summer and Autumn

The study of phytoplankton community structure is one of the core areas of lake ecological research, providing important information on biological resources and the ecological status of lakes. In this study, we investigated the community structure of phytoplankton in Lushanxihai Reservoir, analyzed seasonal and spatial variations, as well as the biodiversity of the phytoplankton community. The data collected were used to evaluate the water quality of Lushanxihai Reservoir. Lushanxihai, a large reservoir (308 km2) located in the northwest of Yongxiu county, Jiangxi province, provides important social functions including drinking water supply, tourism, aquaculture and water for industry and agriculture. During the summer (August) and autumn (October) of 2012, samples were collected at eighteen sites (S1-S4 in open water, S5-S12 in the transition zone and S13-S18 near the inlet). Phytoplankton samples for qualitative analysis were collected using plankton nets and identified by optical microscopy. Water samples from the surface and bottom were collected using glass bottle for four times and mixed in a 10L container. A 1L portion of the well-mixed water was removed for quantitative analysis and the phytoplankton was concentrated to 25mL by settling for 24h. Eight phyla, including 86 species, were found in Lushanxihai Reservoir. Chlorophyta was the dominant phylum and included 43 species, accounting for 59.43% of the total phytoplankton species, followed by Bacillariophyta (17 species) and Cyanophyta (14 species), accounting for 19.54% and 16.09%, respectively. Of the 86 species observed, 14 species from four phyla were dominant during the investigation and included Chlamydomonas reinhardi, Palmellaceae mucosa, Anabaena oscillarioides, Cryptomonas ovate and Chroomonas acuta. The overall mean value of phytoplankton density was 2.20×106 cell/L (range, 4.28×105 - 5.17×106 cell/L), with a mean summer value of 3.15×106 cell/l and mean autumn value of 1.25×106 cell/L. The average biomass was 2.90 mg/L (range, 1.24-7.01 mg/L), with a mean summer value of 3.90 mg/L and mean autumn value of 1.89 mg/L. The Shannon-Wiener diversity index, Pielou evenness index and Margalef richness index were 2.84-4.45, 0.63-0.89, 1.46-3.69, respectively. Phytoplankton density, biomass and species richness varied by season in Lushanxihai Reservoir, higher in summer and lower in autumn, but the biodiversity indices of phytoplankton were higher in autumn than summer. No obvious spatial variation in species diversity and community structure were observed in Lushanxihai Reservoir. The data collected during this study indicates good water quality in Lushanxihai Reservoir with water quality in the transition zone of higher quality in summer and water quality in the lacustrine zone higher in autumn.