近年长江湖口江段鱼类群落组成及多样性

2007~2009年每月2次，其中4~6月每月5次对湖口江段的鱼类群落特征及其多样性组成进行了调查，共收集鱼类样本4 241尾，隶属7科19属26种。群落优势种为黄颡鱼（〖WTBX〗Pseudobagrus fulvidraco）和粗唇鮠（Leiocassi crassilabis〖WTBZ〗），占样本个体总数的6403%；Shannon Wiener多样性指数 (〖WTBX〗H′〖WTBZ〗)为1782，Simpson优势度指数 (〖WTBX〗λ〖WTBZ〗)为054，Pielou均匀度指数 (〖WTBX〗J′〖WTBZ〗)为0547，Margalef种类丰富度指标 (〖WTBX〗D〖WTBZ〗)为2993，Wilhm 改进指数（〖WTBX〗H″〖WTBZ〗）1873，相对稀有种数 (〖WTBX〗R〖WTBZ〗)为5769%；长江湖口江段鱼类群落中体重50~500 g的中小型鱼类占绝对优势，体重>500 g的大型鱼类占的比例非常小，经济鱼类趋于小型化，鱼类群落稳定性较低，生物多样性处于较低水平。 鱼类群落可分为3个生态类型，其中江海洄游性鱼类有3种、河湖洄游性鱼类4种、定居性鱼类19种；食鱼性鱼类有8种，食无脊椎动物性鱼类11种，杂食性鱼类3种，食浮游生物性鱼类有2种，草食性鱼类2种

SPECIES COMPOSITION AND BIODIVERSITY OF FISH COMMUNITY IN HUKOU SECTION OF THE YANGTZE RIVER

The investigation on the species composition and biodiversity of fish community in Hukou section of the Yangtze River was carried out two times monthly from 2007 to 2009,including five times in April June.A total of 26 species and 4 243 individuals were collected,belonging to 19 genera,7 families.The dominant species were 〖WTBX〗Pseudobagrus fulvidraco〖WTBZ〗 and 〖WTBX〗Leiocassi crassilabi〖WTBZ〗，accounting for 6403% of the total fish species.The eigenvalues of species diversity were Shannon wiener’s index (〖WTBX〗H〖WTBZ〗′) being 1782，Simpson’s (〖WTBX〗λ〖WTBZ〗 ) being 054，Pielou’s index (〖WTBX〗J〖WTBZ〗′) being 0547，Margalef’s index(〖WTBX〗D〖WTBZ〗) being 2993,Wilhm's index (〖WTBX〗H〖WTBZ〗″) being 1873 and Relative rare species (〖WTBX〗R〖WTBZ〗) being 5769%.In the fish community,middle small fishes with a mean body weight 50-500 g were the most superior in numbers,but big fishes with a mean body weight more than 500 g were the less percentage in numbers,the capture size of commercial fishes became smaller,and the stability and biodiversity of fish community were lower levels in the Hukou section.The fish community could be classified into 3 ecological types， i.e.，river sea estuarine fish (3 species )，river lake estuarine fish (4 species )，migratory fish (19 species)；piscivorous fishs (8 species )，invertebrate fish (11 species)，omnivorous fishes (3 species)，planktivorous fish (2 species),herbivorous fish (2 species