Abstract: To understand the community characteristics and distribution patterns of meiofauna in the mangroves north of the Tropic of Cancer, we conducted investigations on meiofauna and its sedimentary environment across five habitats (Kandelia obovata, Avicennia marina, Aegiceras corniculatum, Spartina alterniflora distribution areas and naked flat) and two microhabitats (sediment and leaf litter) in the mangrove wetland of Zhangjiang estuary, Fujian Province, and analyzed the community features and influencing factors of meiofauna. A total of 11 meiofauna taxa were found in both sediment and leaf litter. Nematodes and copepods were the first and second dominant taxa, respectively. The average abundance of meiofauna in sediment was 1415.80±495.84 ind·10 cm^-2, and the average biomass was 681.38±165.61 μg·10 cm^-2. The average abundance of meiofauna on leaf litter was 5.36±6.48 ind·g^-1, and the average biomass was 4.81±5.67 μg·g^-1. There were significant differences in the abundance and biomass of meiofauna among different habitats. The abundance and biomass of meiofauna in naked flat were extremely significantly higher than those in the mangrove forest of A. corniculatum. Among the three mangrove habitats, the abundance of meiofauna in the A. marina forest was significantly higher than that in the A. corniculatum forest, while the biomass was extremely significantly higher than that in the A. corniculatum forest. The abundance and biomass of meiofauna were the highest in the surface layer of sediment, which gradually decreased with increasing sediment depth. Meiofauna had highest abundance and biomass on leaf litter with highest decay levels. The community structures of meiofauna were significantly different among the five habitats and the two microhabitats. There were significant differences between naked flat and the other four habitats with vegetation. The abundance and biomass of meiofauna in sediment were significantly positively correlated with sand content and significantly negatively correlated with median grain size. The abundance and biomass of meiofauna on leaf litter were extremely significantly negatively correlated with hydrolyzed tannin content and organic carbon content. The combination of sand content and organic carbon content could best explain the community structure of meiofauna in sediment. The combination of median grain size and organic carbon content could best explain the community structure of meiofauna on leaf litter. Our results indicate that the heterogeneity of habitats and microhabitats has a significant impact on the spatial distribution of meiofauna in the Zhangjiang estuary mangrove wetland. Vegetation types (including the presence or absence of vegetation), sediment grain size, and food resources in habitats were the main environmental factors affecting the spatial distribution of meiofauna.

Key words: meiofauna, mangrove, community characteristics, Zhangjiang estuary