西江鱼类群落结构和环境影响分析

2016-2018年,于珠江干流西江桂平至肇庆6个站点开展了季节性渔获物采集和环境监测,共采集鱼类12目29科99种,单次采集10~45种,香浓威纳指数(H’)为0.90~2.93,均匀度指数(J’)为0.30~0.89,物种组成为季节和空间的周转格局。相对重要性指数表明,鲮(Cirrhinus molitorella)、广东鲂(Megalobrama terminalis)和赤眼鳟(Squaliobarbus curriculus)为主要优势种。置换多因素方差分析表明鱼类群落时空差异显著,夏-冬季间群落结构差异主要源于鲤(Cyprinus carpio)、鲮、广东鲂和赤眼鳟质量百分比(W%)差异;桂平与梧州、肇庆的显著差异主要源于鲮、广东鲂和银(Squalidus argentatus)的数量百分比(N%)差异,以及鲮、广东鲂、鲤、鲢(Hypophthalmichthys molitrix)和尼罗罗非鱼(Oreochromis niloticus)的W%差异。冗余分析分别解释了鱼类N%和W%变异的49.92%和49.61%,主要影响因子为距河口距离、水温、透明度和径流量,且鲮分布在低透明度的高温水域,广东鲂和鲢分布在下游江段,赤眼鳟分布在中上游江段,鲤分布在高透明度的低温水域。

Fish community structure and environmental effects of West River

From 2016 to 2018,we seasonally collected fish and monitored the environmental factors at the six sites from Guiping to Zhaoqing in the West River,the main stream of the Pearl River.In total,we collected 99 species belonging to 12 Orders and 29 Families.The species number collected for each sampling ranged from 10 to 45,while the Shannon-Weiner index ranged from 0.90 to2.93,and the evenness index ranged from 0.30 to 0.89.The species variation was agreed with patterns of seasonal turnover and spatial turnover.As revealed by the index of relative importance,Cirrhinus molitorella,Megalobrama terminalis and Squaliobarbus curriculus were the most dominant fish species.The permutational multivariate analysis of variance indicates that the fish community structure varied significantly among seasons and sites.The significant difference between summer and winter was mainly caused by the weight percentage variation(W%)of Cyprinus carpio,C.molitorella,M.terminalis and S.curriculus.The significant difference between Guiping and lower reaches of Wuzhou and Zhaoqing was mainly caused by the number percentage(N%)variation of C.molitorella,M.terminalis and Squalidus argentatus,and W%variation of C.molitorella,M.terminalis,C.carpio,Hypophthalmichthys molitrix and Oreochromis niloticus.Redundancy analysis explains 49.92%variation of fish N%and 49.61%of fish W%;the most important influencing variables are distance to estuary,water temperature,water transparency and runoff;C.molitorella distributes in water of low transparency and high temperature;M.terminalis and H.molitrix distributes in lower reach;S.curriculus distributes in middle and upper reach;C.carpio distributes in water of high transparency and low temperature.