崇明岛内河大型底栖动物群落组成及分布特征

大型底栖动物是河流生态系统中重要的生态类群，研究其群落组成及分布特征能为河流生态系统管理提供理论支撑。2018年6月(夏季)和11月(秋季)，在崇明岛内河设置16个固定站点，开展了拖网和地笼相结合的大型底栖动物调查，分析研究了崇明岛内河大型底栖动物群落的组成与分布特征及影响因子。调查期间共采集到大型底栖动物14种，分属5目8科，主要为节肢动物。其中，淡水型10种，河口半咸水型3种，降海洄游型1种。从空间分布来看，北横引河记录12种，南横引河记录6种，竖河记录11种；不同河道大型底栖动物群落组成均以淡水型种类为主，主要优势物种为日本沼虾(Macrobrachium nipponense)和秀丽白虾(Exopalaemon modestus)；北横引河大型底栖动物群落的物种数、多度及生物量均高于南横引河；而竖河介于两者之间。夏季大型底栖动物群落的物种数、多度和生物量均高于秋季，季节变化是崇明岛内河大型底栖动物群落组成变化的重要特征之一。综合来看，崇明岛内河大型底栖动物群落组成特征兼具内陆河流和河口区特点，它与崇明岛区位特征、河流水文及生境条件、水质特征及区域人类活动等多种因素有关。

Community composition and distribution characteristics of the benthic macroinvertebrates in the inland rivers of Chongming Island

The benthic macroinvertebrate is the important ecological group in river ecosystem. The study of the community composition and distribution characteristics on the benthic macroinvertebrate can provide theoretical support for river ecosystem management. In June (summer) and November (autumn) 2018, surveys on the benthic macroinvertebrate with trawl and ground cages were carried out in 16 fixed sampling sites in the inland rivers of Chongming Island. The community composition, distribution characteristics and corresponding influencing factors of the benthic macroinvertebrates were analyzed then. A total of 14 species belonging to 5 orders, 8 families of the benthic macroinvertebrates were collected in the surveys. Most of them were arthropods. Among them, 10 species were freshwater type, 3 species were estuarine brackish water type and 1 species was catadromous migration type. And 12, 6 and 11 benthic macroinvertebrate species were recorded in the Beiheng Canal, Nanheng Canal, and the vertical canals respectively. The dominants of the benthic macroinvertebrates were freshwater species, and the common species were Macrobrachium nipponense, and Exopalaemon modestus. The number of species, abundance and biomass of the benthic macroinvertebrates in the Beiheng Canal and the vertical canals were higher than those in the Nanheng Canal. The number of species, abundance and biomass of the benthic macroinvertebrates in the summer were higher than those in the autumn. Seasonal variations were one of the important features of the characteristics of the benthic macroinvertebrate assemblages in the inland rivers of Chongming Island. Add all these together, the inland rivers of Chongming Island had some characteristics of both estuaries and inland rivers, which were related to the geographical location, hydrological conditions, riverine habitats, water quality characteristics and regional human activities of the Chongming Island.