Seasonal dynamics of the juvenile fish community structure in the Maowei Sea mangroves

More than 50% of Chinese mangroves were lost between 1950 and 2000 to habitat destruction, prompting an urge for conservation. To assess the importance of the protected Maowei Gulf mangrove estuary for fish population assemblage in the Beibu Gulf (China), we studied species composition and abundance of juvenile fish (including larvae) from July 2012 to June 2013. A total of 11 691 specimens were collected, which belonged to 24 species and 15 families. Six perciform species constituted 93% of the total sample. Pseudogobius javanicus (53.29%) was the dominant species from August to November, Omobranchus elegans (28.49%) from April to July, non-identified species in December and January, and Liza carinata in February and March. A number of commercially important fish species were also identified. Abundance was the highest in summer/early autumn (max 162.4 in Sep), and lowest in winter/early spring (Mar = 4.5). Diversity (H’) and richness (D(ma)) indices (both max. in May: 1.67 and 1.95 respectively) were generally positively correlated with tide and temperature, and negatively with salinity. Seasonal variations play a more important role in the fish assemblage structure than tidal rhythm, with differences particularly pronounced between colder and warmer months. Despite the prominent seasonal differences in abiotic factors, this study indicates that Maowei mangroves provide habitat and food for juvenile fish throughout the year and thus are indispensable for the fish diversity in the Beibu Gulf.