Review on the fauna and distribution ecology of pelagic chaetognaths in the South China Sea and its adjacent seas

Abstract

The South China Sea and the adjacent areas are included in the Indo-Pacific biogeographic province where the highest species diversities are found for various taxa. In the present paper, we review the chaetognath fauna and distribution in these areas based on the available literature and make remarks on important knowledge gaps that warrant attention in the future. According to the literature, 42 species belonging to 14 genera have been found. The highest number of species was observed in the South China Sea, particularly to the east off the Philippines. Flaccisagitta enflata was the most dominant species in almost all areas while Aidanosagitta species dominated enclosed and shallow areas. Variation in the vertical distribution of the chaetognaths appeared to be associated with physico-chemical parameters, with the greatest abundance in the upper 100 m dominated by F. enflata and gradually decreasing to the mesopelagic zone. In general, the South China Sea and its adjacent seas represent a relatively large number of species accounting for ca. 50％ of the global total of pelagic chaetognath species. This high number of species is still an underestimate considering that a vast portion of the area and numerous islands remain unexplored.