长江常熟江段近岸小型鱼类群落结构及多样性探析

BIODIVERSITY AND COMMUNITY STRUCTURE OF SMALL-SIZED FISH IN THE NEARSHORE OF CHANGSHU REACH IN THE YANGTZE RIVER

2009年3月～2010年2月,利用密目插网对长江常熟江段小型鱼类进行了连续监测,首次对该江段的小型鱼类群落组成、优势种组成及生物多样性进行了剖析。结果表明:该江段共有小型鱼类24种,隶属于5目7科,其中鲤形目最多。根据IRI指数分析,贝氏、刀鲚、窄体舌鳎、蛇鮈和光泽黄颡鱼为优势种,共占总数量的83.44%,占总重量的82.02%;贝氏和窄体舌鳎在各个季节中均为优势种,刀鲚在春、夏、秋3季为优势种。基于渔获数量的分析结果显示,常熟江段各月多样性特征值范围为:Shannon-Wiener指数(H’)1.18～1.76,Margalef指数(R)0.87～2.07,Pielou指数(J’)0.48～0.83,McNaughton指数(Dn)0.57～0.86。Margalef指数和Mc-Naughton指数春季最高,冬季最低;Shannon-Wiener指数和Pielou指数冬季最高,夏季最低。最后探讨了影响该江段小型鱼类群落结构的各种因素,提出了合理开发和保护小型渔业资源的建议。

Based on the fishery survey by setting net from March 9,009 to February 2010,the community structure, dominant species composition and biodiversity of small-sized fishes have been analyzed. 24 species of small-sized fishes were collected,which belongs to 5 orders, 7 families,and most of the species were be- long to Cypriniformes. The dominant species were Hemiculter bleekeri, Coilia nasus, Cynoglossus trigram- mus ,Saurogobio dabryi and Pelteobaggrus nitidus ,which occupied 83.44~ of the total catch in number, and 82.02O/6o of the total weight. Herniculter bleekeri and Cynoglossus trigrammus were the dominant spe- cies in each season,and Coilia nasus in spring, summer and autumn. Four diversity indexes, Shannon-Wie- nerds index （H＇） ,Margalef＇s index（R＇） ,Pilou＇ s index（J＇） ,McNaughton＇s index（Dn） ,were calculated by catch in number to analyze the characteristics of species diversity of fishery communities. The inter-month- ly range of H＇values was 1.18 to 1.76, R＇was 0. 87 to 2.07, J＇ was 0. 48 to 0.83 and Dn was 0.57 to 0.86. Based on research sets by season,in spite of any calculation unit,both by quantity and by weight,the highest value of R＇ and Dn was in spring while the lowest was in winter, and the highest value of H＇ and J＇ were all present in winter while the lowest were in summer. Various factors affecting the small-sized fi- shes resources in this reach were discussed, and several suggestions of how to develop and protect small- sized fishey resources were provided.