Biological nitrogen fixation (acetylene reduction) associated with decomposing Avicennia marina leaves in the Beachwood Mangrove Nature Reserve

Nitrogen fixation of decomposing Avicennia marina (Forssk.) Vierh. leaves was studied over a period of 16weeks under exposed and submerged conditions. Rates of acetylene reduction activity (ARA) were highest under exposed conditions and reached a maximum after three to four weeks. Percentage total nitrogen increased during decomposition, the increase being greatest under submerged conditions, but this was not directly related to nitrogen fixation. Bacteria were considered to be the main agents of nitrogen fixation. Rates of decomposition were highest under exposed conditions. The contribution of nitrogen fixation to the nitrogen budget is significant