Spatial recruitment patterns of Chaetodon butterflyfishes on coral reefs in the coastal waters of Vietnam

Understanding the demographic structure, recruitment patterns, and habitat association of reef fish communities is important for the management of coral reefs. This study assessed spatial recruitment patterns of Chaetodon butterflyfishes (species richness and abundance). The study was conducted across 532 transects of the 72 study sites laid parallel to the shore on reef flats and reef slopes in 6 key locations in the coastal waters of Vietnam, between April-June 2017. Among 23 Chaetodon species, 17 species (74%) with a total of 1,551 recruits were recorded with recruitment. The central area (Cu Lao Cham, Quy Nhon, Nha Trang, and Nui Chua) supported higher species richness of recruits compared to the south-eastern area (Con Dao) plus the south-western area (Phu Quoc). The mean density of recruits in both reef zones was notably higher in the southeastern and southwestern areas, where Chaetodon octofasciatus and C. speculum were dominant. In contrast, the north-central area (Cu Lao Cham, Quy Nhon) and the south-central area (Nha Trang, Nui Chua) exhibited greater species diversity and higher densities of C. lunulatus, C. trifascialis, C. melannotus, C. auriga, C. kleinii, and C. xanthurus. Among these, Nha Trang Bay stood out with the highest species richness and recruit density compared to other central locations. Consequently, enhancing management efforts in the existing MPAs (Cu Lao Cham, Nha Trang, Con Dao, and Phu Quoc) to preserve and represent the Chaetodon assemblage groups across Vietnam's coastal waters should be prioritized in future conservation strategies.