长江安庆新洲水域鱼类群落结构及多样性

沙洲水域环境良好,饵料资源丰富,栖息生境多样,为鱼类的生长繁殖提供了优良的生存环境。为了解长江安庆新洲水域鱼类群落结构特征,于2017年4月、7月、10月和12月对安庆江段新洲水域鱼类群落进行季节性调查。共采集鱼类64种,分属5目11科48属,其中62.5%为鲤科鱼类。以物种数和多样性指数分析群落多样性特征,结果表明新洲水域鱼类种类多样性水平较高。单因素方差分析表明,该群落多样性季节差异显著(P0.05),空间差异不明显。新洲水域鱼类群落优势种为鳊(Parabramis pekinensis Basilewsky, 1855)、鲤(Cyprinus carpio Linnaeus, 1758)、贝氏■(Hemiculter bleekeri Warpachowsky, 1887)、银鮈(Squalidus argentatus Sauvage et Dabry, 1874)和似鳊(Pseudobrama simoni Bleeker, 1864)。4种摄食功能群中,杂食性(42.19%)和肉食性(35.94%)鱼类物种数比例较高;3种生态类群中,淡水定居性鱼类占绝对优势(84.37%);3种栖息水层类型中,底层鱼类物种数比例较高,占37.50%。大型经济鱼类占总渔获物比例低(0.01%),但个体较大,因而相对重要性指数(IRI)高。总体上,新洲鱼类群落多样性和丰富度指数较高,均匀度指数偏低,个体小型化趋势明显。捕捞强度过大、水利工程建设导致的江湖阻隔及外来物种入侵是新洲水域渔业资源衰退的主要因素。由此,建议持续开展长江渔业资源监测,加强长江干流沙洲水域渔业资源保护。

Community structure and species diversity of fish around the Xinzhou shoal in the Anqing section of the Yangtze River, China

Due to good water quality, abundant natural resources, and multiple biotopes, the shoal of Xinzhou provides excellent fish habitat. The community structure and species diversity of fish in the waters around the Xinzhou shoal were investigated seasonally in 2017. A total of 64 fish species from 50 genera, 12 families, and six orders were collected during the investigation, with cyprinids accounting for 62.50% of the collected species. Analysis of species richness and diversity indicated that the fish diversity of the Xinzhou waters was high, with great seasonal variation, and one-way ANOVA indicated that there were no significant spatial differences in fish diversity. Parabramis pekinensis Basilewsky, 1855, Cyprinus carpio Linnaeus, 1758, Hemiculter bleekeri Warpachowsky, 1887, Squalidus argentatus Sauvage et Dabry, 1874, and Pseudobrama simoni Bleeker, 1864, were the dominant species. Omnivorous (42.19%) and piscivorous (35.94%) fish species were the most frequent of the four feeding functional groups, and sedentary fish species (84.37%) were the most frequent of the three ecological groups, whereas demersal fishes (37.50%) were the most frequent of the three habitat types. Large commercial fishes accounts for a very small percentage of the whole fishes, but they have a high relative importance index(IRI) value due to its big body. Overall, both the diversity and richness of the fish community around the Xinzhou shoal were high, and community evenness was stable, even though the trend of miniaturization continued. Overfishing, the disconnection of lakes from the Yangtze river due to hydraulic engineering construction, and alien species invasion could explain why the fishery resources is declining in the last decades. The continuous monitoring of fish resources is recommended to better understand the dynamics of fishery resources and to support the implementation of protection and conservation measures.