阳宗海鱼类群落结构及变化

Structure and Changes of Fish Community in Yangzonghai Lake

【目的】摸清阳宗海鱼类资源现状,分析鱼类变迁,为鱼类管理和湖泊水生态修复提供基础资料。【方法】于2022年3、5、8和10月在阳宗海的10个采样点,使用8种网目刺网和2种地笼开展4次实地调查。采用相对重要性指数划定优势种,采用Shannon-Wiener多样性指数、Pielou’s均匀度指数和Margalef丰富度指数分析鱼类多样性。【结果】采集到鱼类32976尾,共计791694 g,隶属7目11科23属24种;其中鲤科(Cyprinidae)11种,占45.83%;外来种19种,占79.17%;优势种为太湖新银鱼(Neosalanx taihuensis)、鲢(Hypophthalmichthys molitrix)、鳙(H.nobilis)和子陵吻鰕虎鱼(Rhinogobius giurinus)。渔获物中,3月个体数量最多,占41.62%;8月种类数量最多,占95.83%,渔获量也最大,占40.84%;明珠湾个体数量最多,占22.06%,渔获量也最大,占15.82%;阳宗大河口种类数量最多,占91.67%;小型鱼类数量占95.04%;外来种数量占99.27%、质量占97.40%。鱼类多样性为较低至一般水平。与历史记录相比,阳宗海鱼类群落结构已发生较大变化,历史记录的20种土著种仅采集到5种,且为广布、广适种;首次记录到青鱼(Mylopharyngodon piceus)、䱗(Hemiculter leucisculus)、大鳞副泥鳅(Paramisgurnus dabryanus)、鲇(Silurus asotus)、瓦氏黄颡鱼(Pelteobagrus vachelli)和粘皮鲻鰕虎鱼(Mugilogobius myxodermus)。【结论】阳宗海鱼类主要由外来种组成,小型化明显,外来种引入和生境破坏是其主要影响因素。

[Purpose]To ascertain the current situation of fish resources in Yangzonghai Lake,and to analyze the changes of fish,providing basic data for fish management and lake water ecological restoration.[Methods]Four field surveys were conducted in March,May,August and October 2022 at 10 sampling points in Yangzonghai Lake,using eight types of mesh gillnets and two types of ground cages.Relative importance index was used to identify dominant species,and the Shannon-Wiener diversity index,Pielou’s uniformity index and Margalef richness index were used to analyze fish diversity.[Results]A total of 32976 fish individuals weighing 791694 g,belonging to 24 species,23 genera,11 families and 7 orders were collected.Among them,there were 11 species of Cyprinidae(45.83%),19 exotic species(79.17%),and with dominant species of Neosalanx taihuensis,Hypophthalmichthys molitrix,H.nobilis,and Rhinogobius giurinus.The highest number of individuals(41.62%)were caught in March,with the maximal species(95.83%)and weight(40.84%)in August;Mingzhuwan had the highest number of individuals(22.06%)and weight(15.82%),with the maximal species(91.67%)in Yangzongdahekou;the number of small fish accounted for 95.04%;the number of exotic species accounted for 99.27%,and the weight accounted for 97.40%.Fish diversity was low to average.Compared with the historical record,the community structure of fish in Yangzonghai Lake had undergone great changes,and only five species of the 20 endemic indigenous species had been collected from the historical records,and they were widely spread and widely adapted species.Mylopharyngodon piceus,Hemiculter leucisculus,Paramisgurnus dabryanus,Silurus asotus,Pelteobagrus vachelli and Mugilogobius myxodermus were recorded for the first time.[Conclusion]Yangzonghai Lake fish are mainly composed of exotic species,the miniaturization is obvious,and the introduction of exotic species and habitat destruction are the main influencing factors.