Abstract

• Mangrove forests dominate the world's tropical and subtropical coastlines, and provide a unique ecosystem. Mangrove sediments play a critical role in biogeochemical processes by behaving as both source and sink for nutrients and other materials. The interactions of mangrove plant’s growth rate and the sediment nutrients are complex and dynamic. Nitrogen fixation is a process that converted the atmospheric nitrogen gas to ammonium and it is an important source of new nutrient in the mangrove ecosystem. However, the study of nitrogen fixation rate in rhizospheric sediment of mangrove forest is rare, and the factors that regulate N fixation within the biome remain largely unknown. In this study, the rate of nitrogen fixation in mangrove sediment was investigated using the acetylene reduction technique. Sediment samples were collected from Shwe Thaung Yan mangrove forest and were calculated the nitrogen fixation rate. The differences between sediment depths and nitrogen fixation rate, and nitrogen fixation ability at the mangrove forest were described.