长江口崇明东滩水域仔稚鱼种类组成及多样性

Species composition and diversity of fish larvae and juveniles in the water area of Chongming Dongtan, Yangtze River Estuary

为了探明长江口崇明东滩水域仔稚鱼种类组成及其多样性,2020年11月—2021年8月,在长江口崇明东滩周边水域设置14个站点,按季度以大型仔稚鱼网(口径1.3 m,网目0.5 mm)在各站点进行4个航次的表层水平拖网调查,共采到仔稚鱼4 556尾,隶属于8目14科48种。种类组成优势种明显,以凤鲚(Coilia mystus,25.09%)为主,其次为康氏侧带小公鱼(Stolephorus commersonnii,20.12%)和有明银鱼(Salanx ariakensis,17.11%)。春夏两季仔稚鱼密度和种类数显著高于秋冬两季,夏季密度最高,达0.658 ind./m^(3)。春季种类数最多,为28种,冬季种类数最少。种类丰富度指数、多样性指数、均匀度指数均呈相同季节变化趋势:春季最高、夏季其次、冬季最低。春夏季仔稚鱼密度北支高于南支,秋冬季南支高于北支。聚类分析结果显示,春季仔稚鱼可分为淡水类群、河口Ⅰ类群及河口Ⅱ类群;夏季可分为河口类群和海洋类群;秋季长江口崇明东滩仔稚鱼大致分为淡水类群、河口类群与海洋类群;冬季仔稚鱼种类和数量甚少。皮尔逊相关性矩阵分析显示,夏季丰富度指数、多样性指数及均匀度指数均与盐度呈相关关系,与水温、叶绿素、浊度无相关性。文中还对崇明东滩仔稚鱼优势种和群落时空分布特点及影响其分布的环境因子进行探讨。本研究结果可为长江口崇明东滩水域渔业资源的可持续开发和保护提供参考依据。

In order to investigate the species composition and diversity of larvae and juvenile fish in Chongming Dongtan and its surrounding waters,14 stations were set up in Chongming Dongtan and its surrounding waters from November 2020 to August 2021,and surface horizontal trawling surveys were conducted quarterly with large larvae and juvenile fish nets(diameter 1.3 m,mesh 0.5 mm)for four voyages at each station.A total of 4556 larvae and juveniles were collected,belonging to 8 orders,14 families and 48 species.The species composition of dominant species is obvious,of which Coilia mystus(25.09%)was the dominant fish.This was followed by Stolephorus commersonnii(20.12%)and Salanx ariakensis(17.11%).The results showed that the species number and density of larvae and juvenile fishes in spring and summer were significantly higher than those in autumn and winter,and the highest density was 0.658 ind./m^(3 )in summer.The number of species in spring was 28,and the number of species in winter was the least.The species richness index,diversity index and evenness index showed the same trend between seasons,with the highest in spring and the lowest in winter.The density of larvae and juveniles was higher in the north branch than in the south branch in spring and summer,and higher in the south branch than in the north branch in autumn and winter.The results of cluster analysis showed that larvae and juvenile fishes can be divided into freshwater group,estuarine groupⅠand estuarine groupⅡin spring.Summer can be divided into estuarine group and marine group.the larvae and juveniles in Chongming Dongtan of Yangtze River estuary in autumn could be divided into freshwater group,estuarine group and marine group.The species and number of fish larvae and juveniles in winter are very small.Pearson correlation index analysis showed that the richness index,diversity index and evenness index in summer were correlated with salinity,but not with water temperature.The temporal and spatial distribution characteristics of dominant species and communities of larvae and juvenile fish in Chongming Dongtan and the environmental factors affecting their distribution were also discussed.The results will provide important analysis data for the sustainable development and protection of fishery ecological resources in Chongming Dongtan,Yangtze River Estuary.