Abstract

Mangrove litter represents a major source of nutrients and organic matter to coastal aquatic systems.  However, the dynamics of release of these substances from decomposing leaves has been studied little at all.  Here we analyzed the release of organic matter, nitrogen, and phosphorus from decomposing Rhizophora apiculata leaves in the field and under laboratory conditions.  Both in the field and the laboratory the decomposition rate reached a maximum after 30 days of incubation.  The decomposition rate and the release of organic matter were higher at low salinity (5 ppt) than in freshwater (0 ppt) or at high salinities (15, 25 and 35 ppt). 

There was no significant difference between the dry and wet season with respect to the release of organic matter, phosphorus or nitrogen in the field, although phosphorus and nitrogen releases tended to be higher in the wet season.  The decomposition rate was always high when the leaves were completely submersed in the ditches of the mangrove-shrimp systems than when placed on land between the periodically flooded mangrove roots.  Nitrogen and phosphorus concentrations in the decomposing mangrove leaves reached a maximum after six months, suggesting an increase in food quality over the first half year. 

Key words: decomposition rate, nitrogen and phosphorus releases.

Title: Decomposition and nutrient releases of Rhizophora apiculata leaves