西沙群岛珊瑚礁区大型底栖生物群落特征

为了解西沙群岛的珊瑚礁区大型底栖生物群落组成和分布特征，于2016—2019年期间对西沙群岛附近珊瑚礁区的大型底栖生物进行了连续的采样调查，系统分析了该海域大型底栖生物的种类组成、丰度和生物量的分布、生物多样性等生物学特性。结果表明，5个生物大类中的252种底栖生物中，甲壳动物出现的种类最多，有120种；其次为软体动物，有72种；棘皮动物37种，环节动物17种，其他门类生物6种。大型底栖生物密度为（334.45±396.40） ind·m?2，生物量为（110.79±126.56）g·m?2，Shannon-Wiener多样性指数（H’）为3.85±0.84、丰富度指数（d）为5.51±2.64、均匀度指数（J’）为0.89±0.05；多样性指数显示，2016年永兴岛及2018年西沙州海域受到轻度扰动；群落聚类分析显示，该区域大型底栖生物群落随时间变化较显著；丰度-生物量比较曲线法（ABC曲线）评价显示，2017年和2018年的部分岛屿大型底栖生物群落受到一定程度干扰。结果说明西沙群岛珊瑚礁区大型底栖生物群落总体上以软体动物和甲壳动物为主，调查时间的变化比地理位置的变化对底栖生物群落的结构有更大影响。

A survey of macrobenthos communities in coral reef areas of Xisha Islands

A survey was made of macrobenthos from 2016 to 2019 to understand the composition and distribution characteristics of macrobenthos community in the coral reef areas of Xisha islands. Four quadrats were arranged in each coral reef area of Xisha islands and the quadrat size was 0.25 m × 0.25 m. A systematic analysis was made of the species composition, richness, biomass distribution and biodiversity of the macrobenthos collected. The analysis showed that 252 species of macrobenthos were found in 5 biological groups, of which crustaceans were the most common species and had 120 species, followed by mollusc (72 species), echinoderms (37 species), annelids (17 species) and other phyla (6 species). Density of macrobenthos was (334.45±396.40) ind·m?2, biomass (110.79±126.56) g·m?2, Shannon Wiener diversity index (H') 3.85±0.84, Richness index (d) 5.51 ±2.64 and Evenness index (J') 0.89±0.05. According to the diversity index, Yongxing island in 2016 and Xishazhou in 2018 were slightly disturbed. The cluster analysis of the community showed that the macrobenthos communities in these areas changed significantly over time. An abundance/biomass comparison curve (ABC method) was used to assess the status of the macrobenthos communities, and the results showed that macrobenthos communities in some islands of Xisha Islands in 2017 and 2018 were disturbed to some extent. It is concluded that the macrobenthos communities in the coral reef areas of Xisha Islands are generally mainly composed of crustaceans and mollusks, and that the change in time of survey has a greater effect on the structure of macrobenthos community than the change in geological location.