南四湖浮游硅藻季节性演替及其与环境因子的相关性

为研究南水北调东线工程调水对南四湖硅藻藻密度、种群结构变化的影响,于2010年5月—2013年4月在南四湖进行逐月采样,应用NMDS(non-metric multi-dimensional scaling,非度量性多元标度)分析硅藻种群组成的相似性,并通过冗余分析和Pearson相关性分析研究了硅藻种群结构和环境因子间的相关性. 结果表明:①共检出硅藻23属69种,硅藻藻密度在14.3×104~663.2×104 L-1之间,呈明显的季节性变化,表现为冬春季大于夏秋季；②硅藻种群演替呈明显的季节性变化,冬春季主要以冷水种尖针杆藻(冬春季所占比例分别为15.3%、24.0%)为主,夏秋季则以暖水种扭曲小环藻(夏秋季所占比例分别为17.8%、19.1%)为主；③氮磷营养盐水平、pH和表层水温是影响南四湖硅藻种群变化的主要环境因子. 南四湖硅藻种群对于环境因子变化的反应较为灵敏,可作为南四湖水质的潜在指示工具进行长期研究. 

Seasonal Succession of Planktonic Diatom Community and Its Relationship with Environmental Factors in Nansi Lake

To explore the impacts of the South-to-North Water Diversion Project on the change of planktonic diatom abundance and community in Nansi Lake, the diatom community and water quality were analyzed through monthly sampling from May 2010 to April 2013. The similarity of the diatom community from different sampling sites and seasons was analyzed by non-metric multi-dimensional scaling. Redundancy analysis and Pearson correlation analysis were applied to analyze the relationships between the diatom community and environmental factors. The results showed that the diatom community contained 23 genera and 69 species, and diatom abundance ranged from 14.3×104 to 663.2×104 L-1, being greater in winter and spring than in summer and autumn. The diatom community showed an obvious seasonal succession; Synedra acus was the dominant genus in winter for 15.3% and spring for 24.0%, while Cyclotella comta, which represented warm assemblages, was dominant in summer for 17.8% and autumn for 19.1%. Nitrogen and phosphorus nutrients, pH and temperature were the main environmental factors affecting the change of the diatom community. The diatom community in Nansi Lake showed sensitivity to the change in environmental factors, and is suggested to be monitored over the long term as a potential indicator.