2017年4月采用水下录像方式对西沙赵述岛潟湖内外珊瑚礁鱼类种类组成、密度和种类相似度以及造礁珊瑚覆盖率进行评估.共鉴定珊瑚礁鱼类58种,隶属于1纲3目18科37属,其中鲈形目占绝对优势,共55种,占总种类数的94.83%.潟湖内外的珊瑚礁鱼类平均密度存在显著差异,且潟湖内(1.712 3±0.273 2 尾/m2)高于潟湖外(0.655 1±0.029 3 尾/m2).胸斑眶锯雀鲷(Stegastes fasciolatus)、三斑海猪鱼(Halichoeres trimaculatus)、宅泥鱼(Dascyllus aruanus)和栉齿刺尾鱼(Ctenochaetus striatus)为西沙赵述岛的主要鱼类,前3种主要分布在潟湖内,而栉齿刺尾鱼主要分布在潟湖外.潟湖内外珊瑚礁鱼类的种类相似性系数为0.29,属于中等不相似.潟湖内外的造礁珊瑚覆盖率分别为(7.98±9.91)%和(12.35±6.21)%,不存在显著差异.调查区内珊瑚礁鱼类以小型种类为主,珊瑚礁鱼类中食用价值高的石斑鱼科和鹦嘴鱼科的鱼类密度均不高,这可能与日渐退化的珊瑚礁生态功能和日益增加的人类活动相关.
Underwater video surveys were conducted in April 2017 to determine coral reef fish species composition,density,species similarity and stony coral coverage inside and outside the lagoon of Zhaoshu Island,Xisha Islands.Totally 58 coral reef fish species were identified from the videos of the six transects recorded,belonging to one class,three orders,18 families and 37 genera.Among the 58 species,the Perciforms is absolutely dominant with 55 species(94.83%).The fish densities were significant different between inside(1.712 3±0.273 2 ind/m2)and outside(0.655 1±0.029 3 ind/m2)the lagoon(p<0.05).The first four dominant species were Stegastes fasciolatus,Halichoeres trimaculatus,Dascyllus aruanus and Ctenochaetus striatus in Zhaoshu Island waters,of which the first three mainly occurred inside the lagoon and the last species outside the lagoon.The Jaccard's coefficient of similarity of coral reef fishes inside to those outside the lagoon was 0.29,indicating medium dissimilarity of the two habitats.The coverage of stony corals inside the lagoon(7.98±9.91)% was not significantly different from that outside the lagoon(12.35±6.21)%.Dominant fish species in the surveyed areas were small in body size,while highly-valued commercially important reef fishes such as Epinephelidae and Scaridae were of low density.This may due to the reduction in coral reef ecological function and the increase of human activities in Xisha Islands.
