In situ mucus release by Acropora nobilis and degradation of mucus from A. nobilis and Acropora formosa, by heterotrophic bacteria were investigated at Bidong and Tioman Island, Malaysia. Mucus release rate for A. nobilis was on average 38.7 ± 35.2 mg C m -2 h -1 , of which ca. 70% consisted of dissolved organic carbon (DOC) and 30% particulate organic carbon (POC). In the mucus degradation experiment, seawater-mucus mixtures were incubated and compared with control runs for 24 h. Bacterial abundance in the seawater-mucus mixture increased significantly and coincided with a decline in DOC concentration. In controls, bacteria and DOC did not significantly change. The coral mucus had a high content of inorganic phosphate. It is suggested that the coral mucus rich in DOC and phosphate can induce the high bacterial growth.

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The distribution and abundance of planktonic calanoid copepods were studied from samples collected at 13-20 stations during four oceanographic cruises (pre-and post-monsoons, and during northeast (NE) and southwest (SW) monsoons) performed between 1998 and 2000 in the Straits of Malacca. Space and time variations of calanoid copepods were described using univariate (number of species, diversity indices, abundance) as well as multivariate (MDS, ANOSIM, SIMPER) techniques from the ''Plymouth Routines in Multivariate Ecological Research'' (PRIMER) package. There were significant differences in abundance between the cruises. k-Dominance curves also revealed significant differences in the relative species abundance distributions among the monsoon periods, and a decrease in diversity from northern to southern parts of the Straits during each cruise. Multi-dimensional scaling revealed four groups of abundances with differences in species composition. Evidence from analysis of similarity (ANOSIM) suggested that the differences in communities among monsoon periods were significant, although spatial differences among samples in geographic locations in the northern, central and southern parts of the Straits were insignificant. These differences resulted from an overall change in the balance of relative abundance of few dominant species, rather from changes of many species. Similarity percentage analyses (SIMPER) indicated that the major species contributing to the average dissimilarity between monsoons varied temporally.

In order to test the hypothesis that the microbial enrichment in the sea-surface microlayer (SML) over coral reefs is significant, we investigated the abundance and production of the microbial community in the SML and sub-surface water (SSW) at a fringing coral reef of Malaysia. Samples were taken at 2 coral sites with different live coral coverage as well as one offshore site. We detected substantially high enrichment factors (EFs) in abundance (where EF = SML/SSW: the ratio of microbial abundance in the SML relative to SSW) for all biological groups at all sites: up to 6.0 for heterotrophic bacteria, 4.2 for cyanobacteria, 18.8 for autotrophic nanoflagellates and 22.6 for heterotrophic nanoflagellates. We also found that the enrichment factors of microorganisms in coral reefs were remarkably higher than in other marine ecosystems, and a higher concentration of microorganisms was observed in the higher coral coverage site, probably due to higher organic matter released by corals. The higher microbial abundance in the SML over coral reefs may enhance gaseous exchange and carbon flow in the food web through the air-sea interface.