湟水河着生藻类群落结构特征及影响因子分析

Structure Characteristics and Driving Variables of Periphyton Algae Community in Huangshui River

为探究高原河流中着生藻类群落结构时空变化特征,该文选择黄河流域上游支流湟水河为对象,于2020年9月(秋季)和2021年6月(春季)对湟水河流域23个点位开展着生藻类调查,探究湟水河着生藻类群落结构时空格局及其对环境因子的响应。结果表明:湟水河共检出着生藻类5门172种,以硅藻门、绿藻门和蓝藻门为主。主要优势种时空差异明显,上游段着生藻类群落主要由小席藻、鞘丝藻和披针形曲壳藻等清洁种构成,中下游段优势种则逐渐出现放射舟形藻和谷皮菱形藻等耐污种。春季湟水河着生藻类平均密度和平均生物量低于秋季,分别为41.55×10^(4)cells/cm^(2)和66.45×10^(4)cells/cm^(2)、0.60mg/cm^(2)和12.50mg/cm^(2)。春秋两季Shannon-Wiener多样性指数均值上游段均高于中下游段。MRPP检验分析发现,着生藻类群落存在显著的时间(春季v.s.秋季)和空间(上游段v.s.中下游段)差异。就β多样性而言,上游段Jaccard指数低于中下游段,春季Jaccard指数高于秋季。RDA分析识别出春季影响湟水河着生藻类群落的环境因子是硝酸盐、总氮、总磷和溶解氧,秋季影响着生藻类群落的是浊度和总氮。研究结果表明湟水河着生藻类群落与水环境因子变化密切相关,应重点关注流域水土流失防治、氮磷营养盐控制减排等管理内容。

To investigate the spatiotemporal variations in the community structure of periphyton algae in plateau rivers,the Huangshui River,located at the upper region of the Yellow River basin,was selected as the study area.Samples of periphy-ton algae were collected in Sep.2020(autumn)and Jun.2021(spring)at 23 sites in this area.Results showed that the totals of 172 species from 5 phyla were found,and the dominant phyla included Bacillariophyta,Chlorophyta,and Cyanobacteria.Moreover,the key dominant species exhibited pronounced seasonal and spatial differences,the algal community was mainly composed of clean species such as Phormidium tenue,Lyngbya sp.and Achnanthes lanceolata,in the upper reaches while the dominant species in the middle-lower reaches were gradually exposed to pollution-tolerant species such as Navicula radiosa and Nitzchia palea.The average density and average biomass of periphyton algal in the Huangshui River in spring were lower than those in autumn,which were 41.55×10^(4) cells/cm^(2) and 66.45×10^(4) cells/cm^(2),0.60 mg/cm^(2) and 12.50 mg/cm^(2),respectively.In addition,the biomass in the upper reaches(23.59 cells/cm^(2))was also higher than that in the middle-lower reaches(0.40 cells/cm^(2)).The mean of Shannon-Wiener diversity index in the upper reaches was higher than that in the middle and lower reaches in both spring and autumn.In terms ofβdiversity,the Jaccard index in the upper reaches is lower than that in the middle and lower reaches,and the Jaccard index in spring is higher than that in autumn.MRPP analysis found there were significant seasonal(spring v.s.autumn)and spatial(upper reaches v.s.middle-lower reaches)variations in periphyton algal communities.RDA analysis identified that the environmental factors affecting the periphytic algal communities in spring were nitrate,total nitrogen,total phosphorus and dissolved oxygen,while turbidity and total nitrogen affected the periphytic algal communities in autumn.According to the close relationship between periphyton algal communities and water quality parame-ters,more attentions should be paid on the soil erosion control and nutrient concentration control in the ecosystem sustainable management of the Huangshui River.