建塘江浮游植物群落结构特征及与环境因子的关系

Community Structure of Phytoplankton and Its Relationship with Environmental Factors in Jiantangjiang River

为探明浙江省建塘江水质及浮游植物群落结构特征,2017年5—10月,对建塘江水质现状和浮游植物组成进行逐月采样调查。用水质综合指数法对建塘江污染情况进行评价和分析。建塘江水质评价结果处于重污染到严重污染状态,其中总氮、总磷和高锰酸盐指数为主要的超标因子。浮游植物调查结果显示,本次调查共检出浮游植物6门20科38属48种。其中绿藻门22种,蓝藻门10种,硅藻门10种,裸藻门3种,甲藻门2种,隐藻门1种。建塘江浮游植物丰度为86.00×10~4～635.00×10~4个/L,平均丰度为310.00×10~4个/L;生物量为0.14～2.34 mg/L,平均生物量为0.96 mg/L。丰富度指数为1.02～1.68,属于α-中污;香农维纳多样性指数在各采样断面均处于2.00～3.00,属于β-中污;辛普森多样性指数与香农维纳多样性指数基本一致。相关性分析结果显示,浮游植物丰度与温度正相关,而生物量与氨氮呈现显著负相关关系。典范对应分析显示,温度在第1排序轴和第2排序轴上均有较高的贡献率;蓝藻门与温度和总磷含量正相关,表明蓝藻能够适应较高的水温;绿藻门在各个象限均有分布,第2象限包含绿藻门种类最多,说明绿藻门浮游植物能适应高氮营养盐;硅藻门主要分布在第1、2、4象限,与温度呈负相关,说明高温抑制了硅藻的生长。

Water quality and phytoplankton species composition were monthly surveyed in water of Jiantangjiang River from May to October, 2017, and water quality was evaluated by a pollution index method to explore the pollution status of water quality and phytoplankton community structure in Jiantangjiang River. It was found that the water quality in Jiantangjiang exceeded the class V environmental quality standard of surface water, the levels of total nitrogen (TN), total phosphorus (TP) and COD being the main exceeding factors. A total of 48 species (38 genera) of phytoplankton were identified over a total cultured period, belonging to six major functional groups, i.e., Chlorophyta (22 species), Bacillariophyta (10 species), Cyanophyta (10 species), Euglenophyta (3 species), Pyrrophyta (2 species), and Cryptophyta (1 species), with phytoplankton abundance of 86×10^4 -635×10^4 cell/L (average 310.00×10^4 cell/L) and phytoplankton biomass of 0.14-2.34 mg/L (average 0.96 mg/L). The Margalef index (D) was applied to evaluate the sampled water as α-moderately polluted, and variational trend of Shannon-Wiener diversity index ( H′) was ranged from 2.00 to 3.00, showing a β-moderate pollution. Simpson′s diversity index showed a same trend as Shannon-Wiener diversity index ( H′). The Pearson correlation coefficient revealed that phytoplankton abundance showed a positive correlation to the water temperature, while the biomass was negatively associated with NH^+ 4 -N content. Canonical correspondence analysis (CCA) indicated that temperature had a big contribution on both the first and the second ordination biplot. Cyanophyta showed a positive correlation with temperature and TP level, indicating that Cyanophyta adapt for high water temperature. Chlorophyta was mainly distributed in the second quadrant, indicating a good adaptability to high level of nitrogen. However, Bacillariophyta displayed a negative correlation with temperature, indicating that high temperature can inhibit growth of Bacillariophyta.