Affiliations: Laboratory of Microbial Ecology, Institute of
Biological Sciences (Microbiology), Faculty of Science, University of Malaya,
50603 Kuala Lumpur, Malaysia
Abstract: This study was carried out at an inter-tidal site at Cape Rachado
(02°24′48N, 101°51′31E, Fig. 1) from April 2003 until April
2004. A small mangrove forest populated with Sonneratia and Rhizophora trees
was located nearby. Bacterial respiration ranged 0.818–3.208μM
O_2h^{-1}, and the amount of carbon
respired was 9.80–38.44μg C L^{-1}
h^{-1}. Concurrent bacterial production during the
incubation was 1.23–3.28μg C L^{-1}
h^{-1}. Using both these respiration and production values,
we calculated the bacterial growth efficiency, and it ranged 4.0–11.1%.
The low growth efficiency indicated the lower substrate quality here. However
adding nutrients did not significantly increase bacterial growth rates
(Student's t-test for matched pairs: t=1.883, df=2, p>0.10). In this study,
protists consumed 0.49–5.72×10^4 bacterial cells
mL^{-1} h^{-1} or 22 ± 15% of
bacterial production. In carbon equivalents, grazing ranged 0.15–
1.81μg C L^{-1} h^{-1}. Annual
bacterial production at this site is 42.7 g C m^{-3}
yr^{-1}, and carbon consumed by the bacteria was estimated
at 585 g C m^{-3} yr^{-1}. Of this, only
8 g C m^{-3} yr^{-1} was channeled onto
protists. These calculations showed that effectively only 1% of the carbon
consumed by bacteria was passed onto protists. The role of bacteria here was
essentially that of a remineralizer, and as a sink for carbon.
