西江鱼类群落多样性及其演变

Evolvement and diversity of fish community in Xijiang River

2005-2008年对珠江下游西江江段6个采样点进行鱼类多样性调查,共采集鱼类96种,隶属于13目29科75属,辐斑虫纹东方鲀(Takifugu vermicularis)、南方波鱼(Rasbora steineri)、西江鲇(Silurus gilberti)等8种为西江新记录鱼类。西江鱼类群落多度大于1%的种类有17种,前5位依次是鲮(Cirrhina molitorella)、(Hmiculter leucisxulus)、赤眼鳟(Squaliobarbus curriculus)、广东鲂(Megalobrama hoffmanni)、子陵吻虾虎鱼(Rhinogobius giurinus);多度小于0.1的有28种。西江鱼类群落以定居性、杂食性种类为主;与历史比较杂食性、定居性鱼类种类所占百分比上升,肉食性、洄游性、半洄游性鱼类所占比例下降。聚类分析发现西江鱼类群落可以分为3个类群,即:上游类群、中游类群和下游河口类群;物种组成差异分析结果表明,不同江段鱼类群落有明显的差异,相同生境类型江段的鱼类物种相似性较高;上游的物种多样性明显高于下游。通过个体生态学指数(autecology index)分析,西江鱼类群落底层生活、口下位、喜急流生活、肉食性种类受影响程度大,而口端位、杂食性、喜缓流的种类演变成优势种群。航道整治、大规模无序挖沙、河口水体污染、过度捕捞等因素是影响西江鱼类群落变动的主要原因。

The survey was made in Xijiang River from 2005 to 2008. Ninety species belonging to 13 orders,29 families and 75 genura were collected from 6 sampling spots. Eight species including Takifugu vermicularis, Rasbora steineri and Silurus gilberti were newly recorded in Xijiang River. There is 17 species whose relative density 〉1, relative density of 28 species 〈 0.1. The top 5 species in relalitive density were Cirrhina moitorella, Hmiculter leucisxulus, Squaliobarbus curriculus, Megalobrama hoffmanni and Rhinogobius giurinus. Fish communities were dominated by sedentary species and omnivore species. Compared with the historic data, the proportion of omnivore and sedentary species increased. For carnivore, migratory and half-migratory species declined in number. The fish community of Xijiang River can be distinguished as three cluster, upriver cluster, middle reach cluster and downriver cluster. The results indicated that fish species diversity in Xijiang River were significantly different among different sections. Fish species in similar habitats had higher similarity. The diversity of species in the upper stream is higher than that in the downstream. It also showed that these fish species living at downstream of the river with inferior mouth, relishing riffle, decreased greatly in number especially for the carnivore through the individual ecology index. While these with terminal mouth, omnivore , adept to slow current become the dominated species. It is recognized that sea-route renovation, digging sand without control, water pollution and excessive catching is the key factors to impact fish assemble in Xijiang River. [Journal of Fishery Sciences of China, 2010, 17 （ 2 ） ： 298-311]