长江江豚重要栖息地清节洲水域鱼类群落结构

Fish community structure around main habitat of the Yangtze finless porpoise,the Qingjiezhou shoal of Yangtze River

长江清节洲水域是长江江豚的重要栖息地之一,为了解该水域鱼类群落结构特征,于2017年4月、7月、10月和2018年2月对该水域鱼类群落进行了季节性调查。调查共采集鱼类38种,隶属于5目8科29属,其中鲤科鱼类占优势,占总种类数的68.4%。相对重要性指数结果显示鱼类群落优势种为贝氏?(Hemiculter bleekeri)、似鳊(Pseudobrama simony)、银鲴(Xenocypris argentea)和刀鲚(Coilia nasus)。按生活习性划分,定居性鱼类占绝对优势,占总种数的78.9%;在空间上,中上、中下和底层鱼类分布较为均衡,占总种数的比例依次为36.8%,28.9%和34.2%;从食性上划分,杂食性和肉食性鱼类较多,分别占总种数的44.7%和39.5%。Shannon-Weiner指数、Simpson指数、Margalef指数和Pielou均匀度指数依次分别为0.820~1.711,0.601~0.981,1.640~3.423和0.249~0.592。单因素方差分析表明,除春夏季与秋冬季的Margalef指数存在显著性差异(P<0.05),各指数在时间和空间均无显著性差异(P>0.05)。与历史资料相比,该区域鱼类群落呈现物种多样性降低和群落结构小型化的趋势。因此,建议加强该水域鱼类资源的监测和保护,以维护长江生态系统的稳定与江豚栖息地的适合度。

Protection of important habitat is crucial to the Yangtze finless porpoise.The community structure and species diversity of fish in the waters around the Qingjiezhou shoal which is an important habitat for Yangtze finless porpoise were investigated seasonally between April 2017 and February 2018.A total of 38 fish species from 29 genera,8 families,and 5 orders were collected during the investigation,with cyprinids accounting for 68.4% of the collected species.The dominant species were Hemiculter bleekeri,Pseudobrama simony,Xenocypris argentea and Coilia nasus according to the index of relative importance.Sedentary fish(78.9%)species were the most frequent of the ecological groups,and omnivorous(44.7%)and piscivorous(39.5%)fish species were the most frequent of the feeding functional groups,whereas fish species were relatively evenly in spatial distribution.The values of Shannon-Weiner index,Simpson index,Margalef index and Pielou eveness index were 0.820-1.711,0.601-0.981,1.640-3.423,0.249-0.592,respectively.One-way ANOVA indicated that there were no significant differences of fish diversity both temporally and spatially(P>0.05)except for the Margalef index between different seasons(P<0.05).Fish community tended to decline in diversity and miniaturization in individual size when compared with historical data.Therefore,strengthening monitor and protection measures are recommended to maintain the stability of the Yangtze River ecosystem and habitat suitability for the Yangtze finless porpoise.