Taxonomic diversity of fishes from two coral-reef waters of the South China Sea

Context Conservation of coral-reef fishes requires an understanding of their spatial and temporal responses to climate change and anthropogenic disturbance, which also requires an understanding of patterns in their taxonomic diversity. Aims To describe the species composition, taxonomic diversity and G-F diversity-measurement index of Qilianyu Island and Meiji Reef, South China Sea, coral-reef fish assemblages. Methods Coral reef-dwelling fish were sampled in 2018 and 2019 at Meiji Reef and Qilianyu Island by using various fishing gears, identified to the lowest taxonomic category, and their taxonomic relatedness was compared at levels of class, order, family, genus and species. Key results The reef-dwelling fish fauna of this region comprises 123 species in 5 orders (dominated by Perciformes, at 78%), 22 families and 46 genera. The average taxonomic distinctness (Δ+) of Qilianyu Island fish assemblages is 55.52, and variation in taxonomic distinctness (Λ+) is 138.18; for Meiji Reef, values for Δ+ and Λ+ are 53.02 and 135.33 respectively. Conclusions High species diversity and low taxonomic diversity are important features of coral-reef fish assemblages in the South China Sea. Implications The high species diversity of reef fish in the South China Sea, along with a well-distributed assemblage of families and genera, is crucial for preserving the region’s fish biodiversity. Consequently, timely prioritisation of reef fish conservation is essential.