Production, elemental composition and in situ decomposition of litter
of Rhizophora apiculata, R. mucronata, Sonneratia alba and Avicennia o
fficinalis were studied in a mangrove ecosystem fringing Mandovi-Zuari
Estuaries on the Central West Coast of India. Litter yield ranged fro
m 10.2 tonnes ha(-1) year(-1) in A. officinalis through 11.8 (R. apicu
lata and R. mucronata) to 17 tonnes ha(-1) year(-1) in S. alba. Season
ally maximum litter fall was in pre- and post-monsoon months, with the
lowest production in the monsoon. Modelling of litter fall as a funct
ion of Julian day and six environmental parameters showed that the obs
erved changes can be explained in terms of dry/wet season and wind spe
ed, with a <10% difference between calculated and observed annual aver
ages. C, N and P contents of 13 litter fractions in the four species w
ere 41.9-43.4, 0.66-1.15 and 0.054-0.105%. N:P, C:N and C:P ratios wer
e <30, 30-100 and >1000. Total decomposition (98-100% loss in dry weig
ht and C, and >90% loss in N and P) of yellow leaves was within 15 wee
ks in the two Rhizophora spp. and S. alba, and within 8 weeks in A. of
ficinalis. Ln all four species, mass changes during decomposition obey
ed first-order kinetics. Comparison of C, N and P fluxes from the deco
mposing mangrove litter with phytoplankton, bacterial and secondary pr
oduction in the estuarine waters showed that mangrove production is im
portant mainly for the C budget of the Estuaries and in sustaining the
microbial food chain and nutrient regeneration, rather than the parti
culate food chain directly. (C) 1997 Academic Press Limited.