太子河河流等级对鱼类群落结构及环境因子的影响

河流等级是一种用于评价河流生物多样性及环境特征的重要分类标准。以太子河流域为研究区域探究河流等级与鱼类群落分布之间的关系以及鱼类群落分布特征与环境因子之间的响应关系，并将太子河主要支流作为独立流域单元进行相同等级河流之间鱼类群落分布差异的比较。共设置125个点位，分3次调查鱼类群落和水环境理化特征，调查共采集到鱼类18 883尾，分属23科60种，洛氏鱥、宽鳍鱲、北方条鳅、棒花鱼为优势种，分别占鱼类总数的35.52%、8.58%、6.63%、5.53%。太子河流域鱼类群落结构在不同河流等级之间有显著差异，指示种分析表明洛氏鱥与北方条鳅是上游河段的指示种，短须颌须鮈与东北雅罗鱼是中游河段的指示种，?、大鳞副泥鳅及鰕虎鱼类是下游河段的指示种；摄食功能群在各级河流也有显著差异，杂食性鱼类的比例及物种数在三级河流和五级河流较高，昆虫食性的鱼类在一级河流和二级河流比例较高，昆虫食性鱼类的物种数在五级河流较高。河流等级对鱼类群落的物种丰富度和多样性水平有显著影响(F=3.644,P=0.008;F=2.543,P=0.043)，最大值出现在三级河流。各等级河流之间总氮和氨氮有显著差异；相同等级河流...

Effects of Stream Order and Environmental Factors on Fish Community Structure in the Taizi River Basin

In river ecology research, stream order is an important classification standard for evaluating the river biodiversity and environmental characteristics of a river. Studies have shown that there are clear differences in the community structure of fish in different stream orders; however, the question of whether this community structure is maintained when the same stream order is the same, and what impacts the environmental factors driving this have, have a clear internal relevance that needs further study. This study uses the Taizi River Basin as a research area to explore the relationship between stream orders, the distribution of fish communities, and the relationship between the response of fish community distribution characteristics and environmental factors. The main tributaries of the Taizi River were taken as independent watershed units to compare the differences in the distribution of fish communities in the same stream order. The results of the survey of the fish communities and the physical and chemical characteristics of the aquatic environment at 125 points in the Taizi River Basin show that the structure of the fish community in these watersheds are significantly different in different stream orders. Fish diversity and richness are highest in third-order streams, and an analysis of the results shows that Phoxinus lagowskii and Nemachilus nudus are the upstream indicator species; Gnathopogon imberbis and Leuciscus waleckii perform this role in the midstream;, and Hemiculter leucisculus, Paramisgurnus dabryyanus, and Gobiidae sp. are the downstream indicator species. There are also significant differences in feeding function groups in rivers of different stream orders. The number and proportion of omnivorous fishes are higher in third- and fifth-order rivers, and insectivorous fish make up a higher proportion of first- and second-order rivers. The number of fish species is higher in the fifth-order rivers, and there are significant differences in total and ammonia nitrogen in streams of different orders. Furthermore, there are also significant differences in the structure of the fish community conductivity, water temperature, ammonia nitrogen, and other environmental factors in streams of the same order. The results of this study show that there are significant differences in the community structures of fish in streams of different orders in the Taizi River Basin , and the characteristics fish distribution of in streams of the same order ,although the spatial differences in the structure of the fish communities is not affected by the physical and chemical factors of the aquatic environment .