夏季大亚湾鱼类群落结构与多样性

根据2018年8月大亚湾海域底拖网鱼类资源调查数据,分析了大亚湾夏季鱼类群落结构特征。结果表明:2018年大亚湾夏季渔获鱼类56种,隶属9目、34科、47属。其中,鲈形目(Perciformes)最多(39种,69.64%);物种组成以短吻鲾(Leiognathus brevirostris)、黄斑蓝子鱼(Siganus oramin)、拟矛尾鰕虎鱼(Parachaeturichthys polynema)、六指马鲅(Polynemus sextarius)和二长棘犁齿鲷(Evynnis cardinali)等小型低值鱼类为主;鱼类物种多样性存在明显的空间差异,表现为湾口海域最大,沿岸海域次之,湾中部海域最小。鱼类群落结构大体分为咸淡水湾内和海水广布湾口两个鱼类群组;对比1985—2017年夏季调查资料可知,30多年来大亚湾夏季鱼类群落物种多样性减小;优势种组成更替显著,由以大型中上层的经济鱼类为主演变为以小型底层、近底层的低值鱼类为主,其主要原因是人类活动对大亚湾生态系统的干扰,尤其是捕捞致使鱼类群落结构发生改变、趋向简单化。

Fish community structure and diversity in Daya Bay in summer

We investigated the composition,diversity,and structural characteristics of fish resources in summer in Daya Bay,South China Sea,based on data collected from one otter trawl survey in August 2018.The results showed that 56 species were collected in 2018,belonging to47 genera,34 families,and 9 orders.Among them,species of Perciformes(39 species)were predominant,accounting for 69.64%of the total species richness.Dominant species included Leiognathus brevirostris,Siganus oramin,Parachaeturichthys polynema,Polynemus sextarius,and Evynnis cardinali,which are low-value fish with small stature.There was significant spatial variation in fish species diversity,with the greatest value in the mouth area,followed by that of the coastal waters,and the lowest in the central area.The fish community structure could be roughly divided into two groups:bay type with brackish water and bay mouth type with seawater.Compared with the summer survey data of 1985-2017,fish species diversity in the Daya Bay had been decreased over the past 30 years.The compositions of dominant fish species had been changed significantly,from large-stature pelagic economic fish to small-stature and low-value fish in bottom and near-bottom layer.The main reason for such changes was anthropogenic disturbance,especially the fishing activities,which led to simpler fish community structure.