Fish and environmental variable data in mountain streams of the Ren River

The spatial-temporal patterns of fish assemblages in lotic systems can provide useful information in developing effective conservation measures. This study aimed to explore the spatial and seasonal changes in fish assemblages and their association with environmental factors in mountain streams of the Ren River, south-west China. Field investigations were conducted at 18 sites during the rainy and dry seasons in 2017. A total of 1330 individuals, belonging to three orders, eight families, 19 genera and 21 species, were collected. Analysis of similarities (ANOSIM) showed that the structure of fish assemblages varied significantly at the spatial scale, but not at the seasonal scale. In low order sites, fish assemblages were mainly dominated by cold water and rheophilic species (e.g. Rhynchocypris oxycephalus, Scaphesthes macrolepis, Metahomaloptera omeiensis and Gnathopogon herzensteini), while those in high order sites were predominated by warm water and eurytopic or stagnophilic species (e.g. Squalidus argentatus, Hemiculter leucisculus and Zacco platypus). Canonical correspondence analysis (CCA) showed that the fish assemblages were structured by a combination of large-scale landscape factors (e.g. altitude and C-link) and small-scale habitat features (e.g. channel width, water temperature and depth). Among these factors, landscape had the greatest influence on fish assemblages, while local habitat variables were less important or were only significant in certain seasons.

流水生态系统中鱼类群落的时空分布格局，可为制定高效的保护措施提供重要参考。本研究以中国西南部任河山地溪流为研究对象，旨在探究其鱼类群落的空间、季节变化特征及其与环境因子的关联。2017年的丰水期与枯水期，研究人员在18个采样点开展了野外调查。本次调查共采集到鱼类个体1330尾，隶属于3目、8科、19属、21种。相似性分析（Analysis of Similarities, ANOSIM）结果显示，鱼类群落结构在空间尺度上存在显著差异，但季节尺度上差异不显著。在低等级河段，鱼类群落以冷水性和嗜流水性物种为主，例如尖头鱥（Rhynchocypris oxycephalus）、大鳞鳞鲃（Scaphesthes macrolepis）、峨眉平鳍鳅（Metahomaloptera omeiensis）和赫氏颌须鮈（Gnathopogon herzensteini）；而高等级河段的鱼类群落则以暖水性、广适性或喜静水性物种为主，例如银𬶋（Squalidus argentatus）、白条（Hemiculter leucisculus）和宽鳍鱲（Zacco platypus）。典范对应分析（Canonical Correspondence Analysis, CCA）结果表明，鱼类群落结构受大尺度景观因子（如海拔、C-link）与小尺度生境特征（如河道宽度、水温、水深）共同调控。在上述因子中，景观因子对鱼类群落的影响最为显著，而局地生境变量的重要性相对较低，或仅在特定季节表现出显著影响。