Description

[Synopsis]

Japan International Research Center for Agricultural Sciences (JIRCAS) and Malaysia (Fisheries Department, Forestry Department and Malaya University) organized the new project on “Brackish Water Mangrove Ecosystems* from April, 1995 * March, 2000. In three research areas of the mangrove estuary in Malaysia adopted as a project site, the characteristic differences between these are the ratios of the mangrove forests area/river area, in which the values for Matan (4.7), Merbok (2.1) and Lumut (1.1) are calculated, respectively. In the Matang mangrove estuary area (ratio: 4.7), the quantity of fish catch is larger than that in Merbok (ratio: 2.1) and Lumut (ratio: 1.1). In case of the diversity index of fish, however, shows a higher value in Merbok than in the other two mangrove areas. In Lumut, the volume of fish catch and diversity index are the lowest of the three areas. Based on these results, we conclude that the value of the ratio of mangrove forest area/river area is a useful index, with a value of between 4.7 and 2.1 being a precondition for sustainable fish production in mangrove estuary areas.
   The dominant macrobenthic animal group in Matang was the bivalves, accounting for 46 % of the total abundance, but in Lumut, polychaetes were the clearly dominant group, making up about 46 % of the total benthos population. In addition it was fount in this project that wet land retains silicates where phytoalgal diatoms are present at high concentrations, which provide not only oxygen to benthic animals inside the wet land but also flow into the sea, resulting in high concentrations of biomass in seawater. These diatoms repress the growth of dinoflagellates due to the competition among the phytoalgae comunities.