青藏高原拉萨河流域附石藻类群落结构特征及其驱动因子分析

为探究拉萨河中下游流域附石藻类群落结构特征及其驱动因子，于2019年9月采集并鉴定附石藻类，分析了附石藻类物种组成及空间分布状况，并采用冗余分析识别了影响附石藻类群落的关键环境因子.结果表明，共计鉴定出附石藻类6门31属，附石藻类平均细胞密度为1.92×10⁶ cells·m^-2，其中硅藻门种类数和细胞密度在各采样点均最大；干、支流附石藻类种类数和细胞密度差异显著.干、支流的优势藻属差异较小，干流的主要优势属有硅藻门异极藻（Gomphonema）、脆杆藻（Fragilaria）、桥弯藻（Cymbella）和蓝藻门浮鞘丝藻（Planktolyngbya），支流的主要优势属有硅藻门异极藻（Gomphonema）、脆杆藻（Fragilaria）、桥弯藻（Cymbella）和蓝藻门颤藻（Oscillatoria）.冗余分析表明，温度、pH和溶解氧是影响干流附石藻类优势属群落结构的主要驱动因子，HCO₃^-和流速是影响支流附石藻类优势属群落结构的主要驱动因子.本研究为拉萨河中下游流域水生生态系统保护及水质管理提供基础资料和理论依据.

Structure Characteristics and Driving Variables of Epilithic Algae Community in Lhasa River Basin of Qinghai-Tibet Plateau

In order to explore the characteristics and driving factors of the epilithic algae community in the middle and lower reaches of the Lhasa River, epilithic algae was collected and identified in September 2019, the species composition and spatial distribution were analyzed, and the key environmental factors affecting the epilithic algae community were identified through redundancy analysis. The results indicated that 31 genera of epilithic algae belonging to six phyla were identified, and the average cell density of the epilithic algae was 1.92×10⁶ cells·m^-2. The number of species and cell density of the diatom phylum were the largest at each sampling point. The species number and cell density of the epilithic algae were significantly different between the main stream and tributaries. The main stream and tributaries contained relatively small differences in the dominant algae genera, which were Gomphonema, Fragilaria, Cymbella, and Planktolyngbya in the main stream and Gomphonema, Fragilaria, Cymbella, and Oscillatoria in the tributaries. The redundancy analysis revealed that temperature, pH, and dissolved oxygen were the main driving factors affecting the community structure of the dominant genus in the main stream, while HCO₃^- and flow velocity controlled the community structure of the dominant genus in the tributaries. This study provides basic data and the theoretical basis for the conservation of aquatic ecosystems and water quality management in the middle and lower reaches of the Lhasa River.