Abstract
Seven coral reef communities are defined on Shiraho fringing reef, Ishigaki Island, Japan. Then, metabolisms (net photosynthesis and calcification rates) of ten sites including six communities, which are occupied most area on the reef flat and slope, were measured by in situ incubations. In the results, net photosynthesis on the reef flat was totally positive, but reef flat acts as a source for CO2, because calcification/photosynthesis ratio is 2.5 (> 1.67). Moreover, net photosynthesis on the reef slope was negative. It is expected that almost all excess organic productions are effused to the outer reef and are consumed by the community on the reef slope. Therefore, it is, considered that total net organic production on the whole reef system is almost zero and the whole reef system also acts as a source for CO2.
