新安江水库浮游植物的鉴定及群落结构变化

Phytoplankton identification and the variation of community structure in Xin’anjiang Reservoir

为探究新安江水库中浮游植物种类组成和分布以及与环境因子的相关性,采集新安江水库河流区、库区不同深度水样,利用eDNA-高通量检测技术分析浮游植物的时间动态变化和垂直剖面分布特征。结果表明,水库中浮游植物主要由硅藻门、绿藻门、隐藻门和蓝藻门组成。水库的河流区街口断面在冬季的优势属为蓝藻门的双色藻属(Cyanobium, 8.3%~37.5%)、聚球藻属(Synechococcus, 7.6%~30.3%),春季优势属为硅藻门的小环藻属(Cyclotella, 29.3%)、隐藻门的隐藻属(Cryptomonas, 16.2%)。湖泊区大坝前断面冬季和春季的主要优势属是蓝藻门的双色藻属(Cyanobium, 16.0%~60.6%)、聚球藻属(Synechococcus, 7.8%~33.0%)。街口断面小环藻属在5 m水层的相对丰度为15.2%,显著低于其他水层。大坝断面优势浮游植物双色藻属在5 m(50.7%)水层相对丰度显著高于其他两层水体(分别为25.3%和43.2%)。冗余分析表明,叶绿素、水温、化学需氧量和总氮是显著影响浮游植物群落结构和分布的环境因子,eDNA技术在分析水库浮游植物(包括原核藻类和真核藻类)的生物多样性方面具有较大的优势和前景。

To investigate the distribution of phytoplankton as well as their relationship with environmental factors,water samples from different layers were collected in the river and center regions of Xin'anjiang Reservoir.Temporal and vertical variations of phytoplankton were detected using microscopy and Illumina sequencing technique based on eDNA.The results showed that the phytoplankton in the reservoir were mainly composed of Bacillariophyta,Chlorophyta,Cryptota,and Cyanobacteria.The dominant genera at Jiekou section site in the river area of the reservoir were Cyanobium(8.3%-37.5%)and Synechococcus(7.6%-30.3%)in winter,while Cyclotella(29.3%)and Cryptomonas(16.2%)were dominant in spring.The dominant genera of the section in front of dam in winter and spring were Cyanobium(16.0%-60.6%)and Synechococcus(7.8%-33.0%).At different depths,the relative abundance of Chlorella at 5 m depth was 15.2%,which was significantly lower than that in other water layers.The relative abundance of phytoplankton Cyanobium at the 5 m depth(50.7%)was significantly higher than that in the other two layers(25.3%and 43.2%,respectively).Chlorophyll a,water temperature,chemical oxygen demand(COD_(Mn))and total nitrogen were the environmental factors affecting the composition and distribution of planktonic communities.Our findings suggested that eDNA-based technique has great potential in analyzing phytoplankton biodiversity in reservoirs,including prokaryotic algae and eukaryotic algae.