西沙群岛七连屿礁栖鱼类物种和分类多样性

Species and taxonomic diversity of Qilianyu island reef fish in the Xisha Islands

为探讨以西沙群岛七连屿(16°55′N^17°00′N,112°12′E^112°21′E)为代表的典型小尺度范围内珊瑚礁生态系统的物种组成及分类多样性,本文以20世纪70年代、2018-2019年南海七连屿鱼类调查资料为基础,总结七连屿礁栖鱼类物种组成,并利用分类学多样性指数和G(属级)-F(科级)多样性测度指数对七连屿珊瑚礁鱼类物种组成及分类多样性进行研究。结果显示,七连屿海域礁栖鱼类隶属于8目33科70属175种,其中鲈形目(Perciformes)鱼类占绝对优势,占比81%;平均分类差异指数(Δ^+)约为54.19,分类差异变异指数(Λ^+)约为112.35。与国内外不同区域的鱼类群落组成对比发现,七连屿鱼类的Δ^+低于东海陆架、大亚湾和渚碧礁;其Λ+则均低于东海陆架和大亚湾,高于渚碧礁;科级多样性指数(F-指数)平均值为6.23,属级多样性指数(G-指数)平均值为3.09,标准化的G-F指数平均值为0.40。结果表明,七连屿鱼类群落物种间的分类多样性较高,亲缘关系比东海陆架、大亚湾和渚碧礁更为接近。从G-指数、F-指数、G-F指数综合来看,七连屿礁栖性鱼类物种多样性较高,且其科、属的分布在历史上较为合理,但2018-2019年科属多样性显著降低,建议对其及时予以保护。

Herein we investigate the species composition and taxonomic diversity of coral reef ecosystems in a typical small-scale area in Qilian in the Xisha Islands.Based on fish survey data from the Nanhai Qilian Islands fishery in the 1970s and 2018-2019,we summarized the species composition of the Qilian Islands reef fish species using the taxonomic diversity index and the G(genus)-F(family)diversity measure index.We found that the reef fish in the Qilian Islands area belonged to 175 species of 70 genera,33 families,and 8 orders.Perciformes accounted for the largest percentage,at 81%.The average classification difference index(Δ+)is about 54.19,and the classification difference variation index(Λ+)is about 112.35.We compared the community composition of Qilianyu fish to different regions,both at home and abroad.We found that theΔ+of the Qilianyu fish is lower than the East China Sea shelf,Daya Bay,and Yubi Reef,but was higher than the Qibi Reef.The average grade-of-diversity index(F-index)was 6.23.The(G-index)average was 3.09 and the normalized G-F index average was 0.40.The results indicate that the classification of species in the fish community of Qilianyu is higher,and the genetic relationship is closer,than that of the East China Sea shelf,Daya Bay,and Zhubi Reef.The G-index,F-index,and G-F index values indicate that the species diversity of the reef fish in Qilianyu is relatively high,and that the distribution of families and genera was good historically.However,in 2018-2019,the diversities of the family and genus decreased significantly,so it is suggested to protect them in time.