To investigate the ecological impacts of Spartina alterniflora invasion on meiofaunal community of mangrove wetland, field sampling was conducted in an Avicennia marina mangrove wetland in Zhulin Forest, Beihai, Guangxi Zhuang Autonomous Region in September 2021. The results showed that: compared with the A. marina section and the A. marina-S. alterniflora ecotone section, the S. alterniflora section had the lowest number of meiofaunal taxa (only 7 taxa). The abundance and biomass of meiofauna differed significantly between sections and tidal levels. The S. alterniflora section showed the highest meiofaunal abundance (2561.40 ind ∙ 10 cm^-2) and biomass (2117.66 μg ∙ 10 cm^-2) at the mid-tidal level, and the lowest abundance (29.16 ind ∙ 10 cm^-2) and biomass (33.26 μg·10 cm^-2) of meiofauna at the low-tidal level. The vertical distribution pattern of meiofauna at the high-tide level in the S. alterniflora section was different from the other two sections, with the highest percentage of abundance in the deepest sediment layer (5~10 cm). The community structure of the S. alterniflora section differed significantly from the other two sections, with higher nematode abundance (1126.83 ind ∙ 10 cm^-2). Abundance and biomass of meiofauna were highly significantly and positively correlated with Phoeophorbide a content. The distribution of meiofauna community was best explained by the combination of environmental factors including sediment sorting coefficient, Phoeophorbide a content, hydrolyzed tannin content and clay content. The invasion of S. alterniflora may directly or indirectly affect the spatial distribution of the meiofauna community by changing the habitat structure of the native mangrove community and influencing the habitat conditions such as sediment grain size, food sources and stress factors (e.g. sediment anoxia).

To explore the distribution characteristics of meiofauna communities across mangrove vegetation types and internal microhabitats, an investigation was conducted in September 2021 at the Dongwei Mangrove Reserve in Guangxi Zhuang Autonomous Region. The spatial distribution of meiofauna in Kandelia obovata, Avicennia marina, Aegiceras corniculatum, Excoecaria agallocha, bare flat and internal microhabitats (sediment and leaf litter) was studied, and the influencing factors were analyzed. 10 and 11 meiofaunal taxa were identified from sediment and leaf litter, respectively. The average abundance of meiofauna in sediment was (577.22±448.52) ind.·10 cm^-2 with an average dry mass biomass of (502.33±379.25) μg·10 cm^-2. The average abundance of epiphytic meiofauna on leaf litter was (28.36±21.21) ind.·g^-1 with an average dry mass biomass of (26.14±5.57) μg·g^-1. The abundance and biomass of both sediment and leaf litter meiofauna varied significantly among habitats. No significant correlation was observed between the abundance and biomass of sediment meiofauna and the measured environmental factors. The abundance of epiphytic meiofauna on leaf litter was significantly and positively correlated with the chlorophyll a content and the pheophorbide a content of surface sediment, and biomass was significantly and positively correlated with the chlorophyll a content of surface sediment and the cellulose condensed tannins content of leaf litter. There were significant differences in meiofaunal community structure among habitats, with organic carbon content best explaining sediment meiofaunal community structure, and the combination of environmental factors, including chlorophyll a content and organic carbon content best explaining the community structure of meiofauna on leaf litter. Significant differences in meiofaunal communities between sediment and leaf litter were also observed. The results indicated that the spatial distribution of the meiofauna community in the wetlands was influenced by the combined effects of vegetation coverage, vegetation type and microhabitat type. The spatial heterogeneity of available food resources might be the primary environmental factor shaping the attributes of the meiofaunal community distribution.

To understand the community characteristics, such as the abundance and biomass of meiofauna, and their influencing factors in different typical mangrove habitats, an investigation was carried out on understory meiofauna and its sedimentary environment in five typical mangrove forests in Hainan Dongzhaigang National Nature Reserve, China in November 2020. A total of 17 meiofauna groups were identified. Nematoda and Copepoda were the first and second dominant groups with relative abundance of 77.79% and 15.65%. The average abundance and biomass of meiofauna were (487.9±134.0) ind./10 cm² and (415.0±128.1) μg/10 cm², respectively. Meiofauna abundance was not significantly different but meiofauna biomass was significantly different among the five mangrove forests. There was no significant correlation between the abundance and biomass of meiofauna and environmental factors. Community structure of meiofauna was significantly different among the five mangrove forests. The combination of "skewness coefficient+content of Chlorophyll a" could best explain the community structure.

To explore the community characteristics of meiofauna in different microhabitats in mangrove ecosystem and to supplement the research data of meiofauna in the understory of mangrove wetland in China, an investigation was conducted on meiofauna in Futian Mangrove Nature Reserve, Shenzhen in January 2021 to study the spatial distribution of meiofauna in sediment and on leaf litter, the influencing environmental factors were analyzed. 9 and 12 meiofauna taxa were identified from sediment and leaf litter, respectively. The abundance and biomass of meiofauna in sediment were significantly different among sections and among tidal levels, but the abundance and biomass of meiofauna on leaf litter showed weak spatial heterogeneity. Correlation analysis showed that the abundance and biomass of meiofauna in sediment and on leaf litter were not significantly correlated with the measured environmental factors. There was no significant difference of meiofauna community composition among sections and among tidal levels, but the difference was significant between sediment community and leaf litter community, which indicated that the community structure of mangrove meiofauna was affected by different microhabitats.