长江口横沙浅滩及邻近水域夏季游泳动物群落结构分析

为了解长江口横沙浅滩及邻近水域游泳动物群落结构状况，分析其是否受河口工程建设的影响，本研究于2019年6月对该水域展开底拖网数据调查，通过分析其优势种、物种多样性、群落结构特征来了解群落结构现状。结果显示，夏季该水域共出现游泳动物68种，种类组成主要以节肢动物和鱼类为主。优势种分别为安氏白虾（Exopalaemon annandalei）、葛氏长臂虾（Palaemon gravieri）和矛尾虾虎鱼（Chaeturichthys stigmatias），主要为小型、低营养层次和短生命周期的物种。调查水域游泳动物生物多样性指数偏低，群落结构总体不稳定，受环境扰动较大。聚类和排序分析显示调查水域站位大致可分为两组，并且两组组间物种群落结构差异极显著（R=0.825，P<0.01），主要是受到盐度和水温的影响。总体上看，近年来长江口深水航道和滩涂围垦等工程的建设可能对横沙浅滩及邻近水域游泳动物群落结构造成了一定程度的影响。

Community structure analysis of swimming species in the Yangtze River estuary Hengsha Shoal and adjacent waters in summer

Hengsha Shoal is located in the Yangtze River estuary, which is rich in biological resources. However, in recent years, owing to construction in the estuary, the community structure of aquatic species in this area has changed. To understand the community structure of swimming species in the Hengsha Shoal and adjacent waters of the Yangtze River Estuary to determine the construction effect, this study carried out a bottom trawl data survey in the summer of 2019. The community structure was analyzed by studying the dominant species, species diversity, and community structure characteristics. The results showed that there were 68 swimming species in summer, including 29 fish species, including 8 orders and 16 families; 30 arthropod species, including 2 orders and 15 families; and 9 mollusks species including 4 orders and 7 families. The species composition mainly comprised arthropods and fishes. The dominant species were Exopalaemon annandalei, Palaemon gravieri, and Chaeturichthys stigmatias, which are mainly small, low nutrition, and short life cycle species. The population characteristics showed a trend of miniaturization and low nutrition. The survey showed that the biodiversity index in this area is low, the community structure of swimming species is generally unstable, greatly disturbed by the environment, and there are obvious spatial differences. The results of cluster and ordination analyses showed that the investigated area can be roughly divided into two groups, and the differences of species community structure between the two groups were very significant (R=0.825, P<0.01). The main contributing species of the differences between the groups were E. annandalei, P. gravieri, C. stigmatias, and Larimichthys polyactis, and salinity and water temperature were the main factors that contributed to differences of community structure. Generally, recent beach reclamation and construction of a deep-water channel may have impacted the community structure of swimming species in Hengsha waters.