Internal loading and phosphorus resorption efficiency of A. marina and B. cylindrica in Uttan mangroves.

Abstract

Mangroves are one of the highly productive ecosystem. Upon senescence and decomposition of organic matter produced by mangroves, it contributes nutrients to the ecosystem. The internal loading of phosphorus (P) from two mangrove species, Avicennia marina and Bruguiera cylindrica from Uttan mangroves, was analysed by collecting litter-fall fortnightly during post monsoon season of 2008 and 2009. Litter-fall collected had only leaves, no other plant part was observed. A. marina and B. cylindrica contributed 13.15 and 8.52 g. m-2.month-1 litter-fall input to the sediment respectively. The litter-fall rate was significantly higher in 2009 (11.94 g.m-2) than 2008. The resorption efficiency (RE) was calculated by comparing the concentration of P in the matured leaves and litter fall. The matured leaves of A. marina (1754.70 mg.kg-1) had significantly higher concentration of P than that of B. cylindrica (1250.00 mg.kg-1). A. marina (37.01%) exhibited high P resorption than the B. cylindrica (33.80%).63% and 66% of P in the matured leaves of A. marina and B. cylindrica, respectively is brought back to the system through leaf-litter. In terms of internal loading of P, A. marina and B. cylindrica contributed 13.88 and 7.50 mg P. m-2. monthm-1 respectively to the ecosystem.