抚仙湖浮游植物群落结构特征及多样性研究

Community Structure and Biodiversity of Phytoplankton in Fuxian Lake

为了了解抚仙湖浮游植物群落结构特征,于2014年9月（秋季）、2014年12月（冬季）、2015年3月（春季）以及2015年7月（夏季）对抚仙湖进行采样,在全湖共设置12个样点,通过野外调查及实验室研究的方法,对抚仙湖浮游植物群落结构及物种多样性进行了分析。结果表明,抚仙湖共有浮游植物8门、66属、101种,种类构成比例中,绿藻占54.46%、硅藻占21.78%、蓝藻占9.90%、其他13.86%;不同季节浮游植物的种类组成差异极显著（P〈0.01）,夏季种类最多,有79种,冬季最少,仅有61种。优势度分析显示,抚仙湖共有优势种4门、13种,其中绿藻门最多,有8种,且在全年均形成优势种,蓝藻在夏季、秋季和冬季成为优势种,硅藻和金藻在春季和夏季形成优势种。抚仙湖浮游植物细胞密度为29.9×104~193.2×104个/L,平均为61.51×104个/L;生物量为0.242~0.567 mg/L,平均为0.455 mg/L。浮游植物Margalef丰富度指数为2.31~3.18,Shannon-Weaver多样性指数为3.14~3.65,Pielou均匀度指数为0.89~0.95,综合评价抚仙湖水体为无污染至轻污染。聚类分析表明,抚仙湖浮游植物的种群结构四季变化明显,不同区域浮游植物的种类和密度差异较大。将抚仙湖浮游植物与国内外典型的贫营养湖泊进行相似性比较,Jaccard相似性指数表明,抚仙湖浮游植物群落与其他湖泊均为极不相似,说明其物种及群落结构具有一定的独特性。

Fuxian Lake,located in central Yunnan Province,is a typical deep plateau fresh water lake and a typical oligotrophic lake. In recent years,economic development in the river basin has influenced water quality in Fuxian Lake and algal blooms have occurred in the west,south and north of the lake in 2005 and 2007. The phytoplankton community structure reflects the state of water quality and we characterized the phytoplankton community structure by field investigation and laboratory research,primarily focusing on seasonal variation of species composition and diversity. Our study provides scientific evidence on the impact of exploiting the water resource that will support the effort to protect water quality in the lake basin. From September 2014 to July 2015,seasonal sampling of phytoplankton was carried out at 12 sites in Fuxian Lake： five sites（ No. 1,2,10,11,12） in the middle-south area influenced by tourism and rural non-point pollution; 5 sites（ No. 4,5,7,8,9） in the north area are influenced by tourism,rural domestic waste,fertilizer and phosphorus mining; 2 sites（ No. 3,6） in the central lake where water quality remains good. A total of 101 phytoplankton species,falling into 66 genera and 8 phyla,were identified in Fuxian Lake. Chlorophyta dominated the phytoplankton community,with 54. 46% of the total species,followed by Bacillariophyta（ 21. 78%）, Cyanophyta（ 9. 90%） and others species making up the remaining（ 13. 86%）. Species composition varied significantly by season,with the highest species richness in summer（ 79）and the lowest in winter（ 61）. There were 13 dominant species in Fuxian Lake,with absolute dominance by Chlorophyta（ 8 species）,which were detected year round. Cyanophyta dominated in summer,autumn and winter,one Bacillariophyta species dominated in spring and one Chrysophyta species dominated in summer. The range of phytoplankton density and biomass was 29. 9 × 104- 193. 2 × 104 cells / L and 0. 242- 0. 567 mg / L,with average values of 61. 51 × 104 cells / L and 0. 455 mg / L. The Margalef index,Shannon-Weaver index and Pielou evenness index ranges of the phytoplankton community were 2. 31- 3. 18,3. 14- 3. 65,and 0. 89- 0. 95,respectively. Based on our comprehensive assessment,the water quality of Fuxian Lake was rated as either not polluted or slightly polluted. Cluster analysis shows that phytoplankton community structure of Fuxian Lake changed significantly in different seasons and phytoplankton species and cell density displayed obvious spatial differences. The Jaccard index was used to measure the similarity of phytoplankton communities between Fuxian Lake and other typical oligotrophic lakes at home and aboard,and the results show that phytoplankton community structure and species in Fuxian Lake is unique.