Reef fish diversity and community pattern of the Xisha Islands, South China Sea

In order to explore the diversity, trophic level characteristics and distribution pattern of coral reef fishes in Xisha Islands, the fish communities were monitored using diving surveys in 6 coral reefs (Beijiao Reef, Zhaoshu Island, Xishazhou Reef, Yuzhuo Reef, Huaguang Reef, Jinqin Island) of the Xisha Islands in May 2019, and the species composition, dominant species, and community pattern were analyzed. A total of 116 fish species which belong to 3 families and 21 orders were recorded during the survey. The four most dominant species were Ctenochaetus striatus, Chromis fumea, Chlorurus japanensis, and Scarus forsteni. Shannon-Wiener diversity indices ( H') ranged from 1.57 to 2.58 among the six reefs, with an average of 2.07. Large reef fish indexes ( LRFI) ranged from 0 to 0.86 among the six reefs, with an average of 0.4. Mean trophic level ( MTL) ranged from 2.24 to 3.17 among the six reefs, with an average of 2.74.Three major groups were identified based on fish assemblages, with group A located in the lagoon composed of coral reef and seagrass bed, group B located in the Yongle Islands and Group C in the Xuande Islands.