Abstract: The habitat heterogeneity induced by micro-topographical element has important effects on the spatial heterogeneity of meiofauna. on the high salt marsh of the southern bank of the yangtze estuary, Biogenic structures such as Phragmites culms and Sesarma dehaaniburrows provided variations in surface topography, and Phragmites rhizomes and roots added structural heterogeneity to the subsurface environment. on the high marsh of the estuary, nematodes and copepodes were numerically the most abundant meiofauna taxon,while the micro-polychaete, oligochaetes, ostracods and kinorhynchs were less abundant components. There were significantly more total meiofauna in samples taken between plants than in samples from around plants. The meiofaunal density in samples taken around crab burrows was higher than that in samples from between crab burrows. Analysis for four different habitats demonstrated that all samples contained the majority of meiofauna in the top 1.0 cm fraction of sediment. Meiofauna's aggregation to the sediment surface and the spatial heterogeneity may relate to many factors, such as biogenic structure, food availability, seasonal change of predation and oxygen limitations in the deeper fraction of sediments. Biogenic structures significantly affected meiofaunal distribution and must be taken into account when quantifying meiofauna in areas with much structural heterogeneity.

Key words: Rice field, Ammonia volatilization, Wet deposition