长江口春季鱼类浮游生物群落结构与环境因子的关系

随着源源不断的淡水径流入海与营养物质的输入，使长江口及其邻近海域成为生产力最高的水域，也孕育了我国近海重要的舟山渔场、吕泗渔场和长江口渔场。成淡水的交汇形成了长江口水域复杂的水文物理条件，使之成为众多鱼类的产卵场和育幼场(赵保仁等，1992；罗秉征等，1994)。河口鱼类浮游生物群落结构及其季节变化格局，既受制于其生殖种群的资源量，也与水域环境稳定性密切相关(Blaber et al.，1997；Joyeux，1998；Whitfield，1999)，因而受到国内外的广泛关注。有关以成体为基础的河口鱼类群落生态学已有较多的调查研究(杨伟祥等，1992；朱鑫华等，1994a，b)；而鱼类补充群体的研究，亦多集中于鱼卵和仔稚鱼的种类组成和分布等(杨东菜等，1990；沙学绅，1962)。本文利用1999年5月长江口生态环境与资源综合调査资料，主要研究鱼类浮游生物群落结构及其与环境因子的关系，以期深入探讨河口区鱼类补充过程与近海资源数量变动的关系，为动态监测三峡工程对河口生态环境影响提供科学依据。

RELATIONSHIP BETWEEN COMMUNITY STRUCTURE OF ICHTHYOPLANKTON AND ENVIRONMENTAL FACTORS IN THE ESTUARY OF CHANGJIANG RIVER IN SPRING

The analyses of data, obtained in comprehensive surveys on the fisheries ecology and oceanography in the Changjiang River estuary May, 1999 indicated that the ichthyoplankton community structure and its spatiotemporal dynamics could be related to the construction of the Three-Gorge Dam in the upstream and the recruitment mechanism of commercial fisheries in the waters. It was showed that hydro-physical conditions in the Changjiang River Estuary are complicated with great variation in salinity and transparency. Under this variable environment, sixteen families and 20 species of ichthyoplankton were recorded with 6644 eggs and 14932 larvae in the samples. In both the vertical and surface sampling, the number of Engraulis japonicus was dominated, comprising 95.53% in the vertical water body, and 90.80% in the surface; the second was Chaeturichthys hexanema; and the third was Chaeturichthys hexanema and Hemisalanx prognathus Liza haematocheila. was the second and third in vertical waterbody; and in the surface water body, the second and third were Chaeturichthys hexanema and Coilia mystus. With regard to the index of relative importance (IRI), Engraulis japonicus was absolutely dominant component; Chaeturichthys hexanema were dominant components, with IRI of more than 100 4 regular components with IRI of 10-100 were Coilia mystus, Hemisalanx prognathus, Liza haematocheila and Pseudosciaena polyactis. Surface temperature significantly affected egg survival and occurrence in horizontal samples; the obviously close relation of zooplankton biomass to larvae development in the vertical samples could indicate the direct impact from the hydroelectric facility in the upstream Changjiang River on the developmental environment in the ecosystem.