Comparison of meiofauna, particularly free-living marine nematode community in interspersed habitats of mangroves and Spartina alterniflora in Zhanjiang, China

The invasion of Spartina alterniflora poses a significant threat to mangrove wetlands but its effects on free-living marine nematodes (nematodes, hereafter), the most abundant benthic animals, are understudied. This research compared sediment meiofauna, particularly nematodes, in habitats dominated by S. alterniflora (an invasive species), two native mangrove species (Avicennia marina and Sonneratia apetala), and bare mudflats in Zhanjiang, China. Results show that surface sediment of S. alterniflora had lower pH, salinity, SOM, TP, Cu, Pb and Cr than bare mudflat although the values were comparable between S. alterniflora and A. marina habitats. S. alterniflora sediment also had similar nematode abundance as that in mudflat, but its Shannon-wiener diversity (H'), Pielou's evenness (J'), Margalef's richness (D) and maturity index (MI) were significantly higher. Nematode abundance in S. alterniflora sediment was lower than that in other vegetated habitats, but its diversity indices were comparable to that in A. marina habitat. In S. alterniflora invaded habitat, the abundance of nematodes in rhizosphere was similar to that in surface sediments, but feeding types were significantly different between these two types of sediments. These findings demonstrate that S. alterniflora invasion alters nematode community composition in mudflat ecosystems.