安谷水电站施工期浮游植物群落特征与分析

为了探究水电站施工建设对浮游植物群落结构的影响,于2014年5月和10月对安谷水电站工程所在的大渡河河口进行了浮游植物采样调查,并与工程建设前进行了对比分析。结果表明,调查期间共采集到浮游植物7门、48属、115种,主要由硅藻(占总种数65.21%)、绿藻(20.00%)、蓝藻(9.57%)、裸藻(2.61%)组成;优势种有美丽星杆藻(Asterionella formosa)、颗粒直链藻(Melosira granulata)、双头针杆藻(Synedra amphicephala)、细小桥弯藻(Cymbella pusilla)、尖头舟形藻(Navicula cuspidada)、变异直链藻(Melosirs varians)等17种。8个采样点浮游植物密度和生物量有明显的季节变化,且变化趋势相同,即春季高于秋季。浮游植物现存量的水平分布以安谷库尾断面最高,平均密度为123.70×10~4个/L,平均生物量为1.1658mg/L;安谷库区断面最低,平均密度为69.42×10~4个/L,平均生物量为0.4457mg/L。研究显示,安谷水电站施工期浮游植物种类、优势种、密度、生物量组成及其季节分布趋势与施工前无明显差异,但这些指标的空间分布与施工前存在一定差异。主要是工程施工造成了河道地形结构的改变,特别是直接受影响的库区、坝下水体中,浮游植物的密度、生物量、多样性指数变化明显。

Phytoplankton Community Structure Upstream and Downstream of Angu Hydropower Station During Construction

Angu Hydropower Station is the last of the cascaded power stations on Dadu River and construction began in March 2012. In this study, we analyzed the phytoplankton community structure in Dadu River cove during the construction of Angu Hydropower Station. Results were compared with those from a previous survey of the same area before the project, aiming to explore the effect of construction on phytoplankton community structure and provide data to support habitat protection and management during construction. The survey included phytoplankton species composition, density, biomass, spatial distribution and community diversity in May and October 2014 at sampling sites upstream and downstream of the dam. Samples were collected at eight sites: S1, reservoir backwater; S2, reservoir open area; S3, downstream of dam; S4, Dadu River cove; S5-7, river-left bank; S8, Minjiang River downstream of Dadu River confluence. A total of 115 phytoplankton species belonging to 48 genera and 7 phyla were recorded, dominated by Bacillariophyta (75 species, 65.21%), followed by Chlorophyta (23 species, 20.00%), Cyanophyta (11 species, 9.57%) and Euglenophyta (3 species, 2.61%). The dominant species were Asterionella formosa, Melosira granulata, Synedra amphicephala, Cymbella pusilla, Navicula cuspidada and Melosirs varians. Phytoplankton density and biomass at the eight sites varied markedly, but the seasonal dynamics were similar; the phytoplankton density and biomass in spring were higher than in autumn. The standing stock was highest in the backwater area of Angu Reservoir, with a mean density of 123.70×104 ind/L and mean biomass of 1.1658mg/L, and lowest in the open area of Angu Reservoir with a mean density of 69.42×104 ind/L and mean biomass of 0.4457 mg/L. There was no significant difference in phytoplankton species composition, dominant species, density, biomass or seasonal distribution before and during construction. However, the spatial distribution of these indicators did display differences during construction, due primarily to changes in river channel structure, especially in the reservoir and downstream, where phytoplankton density, biomass and diversity changed markedly.