Effects of Spartina alterniflora Invasion on Community Characteristics of Meiofauna in Zhulin Mangrove Wetland

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).