We observed the reflectance spectra of naturally bleached corals and of experimentally stressed corals exposed to high temperature and strong solar radiation, and analyzed changes in reflectance spectra, photosynthetic capacity, and zooxanthellae status. In response to stress, the corals became dominated by degraded, shrunken zooxanthellae, and their photosynthetic capacity decreased. Degraded, pale-transparent zooxanthellae dominated in the naturally bleached corals, which had low photosynthetic capacity. Differences in the type of degraded zooxanthellae in the experimentally and naturally bleached corals suggest that the degradation pattern reflects the mode of stress (acute or chronic). In both experimentally stressed and naturally bleached corals, the red edge in the reflectance spectra shifted to a shorter wavelength. In the stress experiment, the shift was observed prior to visible bleaching. We propose that spectral reflectance is a useful indicator of coral stress.

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Coral reef seawater samples from Bora Bay off Miyako Island in Okinawa, Japan were incubated with an initial volume of 20 liters. The degradation of organic carbon in this seawater was monitored for more than three months in dark, unstirred polycarbonate vessels by measuring the concentration of organic carbon in the seawater. The concentration of organic carbon gradually decreased to the background level of the refractory organic matter. The ratio of labile organic carbon to total organic carbon was about 30% in the water within the reef, and 10% in the water outside. The concentration of inorganic nutrients gradually increased with the degradation of the organic matter. In terms of the cell density and cell biomass of bacteria, the doubling rate was initially about twice a day and then declined during the incubation. Rate of degradation of labile organic carbon was about 20mmol C/m²/day in the reef. It was much smaller than the respiration rate reported for the whole coral reef community. This indicates that benthos like corals plays a major role in carbon dynamics in the coral reef. The result that the refractory organic concentration in the reef is lower than that in the outer sea indicates that the coral reef has the role of carbon sink in that organic carbon might be absorbed to the sedimentation particle.

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Changes in the surface cover and distribution of the encrusting anemone Zoanthus spp. in the infra-littoral zone at Sakurajima, Kagoshima, Japan were investigated in 1982, and during the period between 1995 and 2002. A belt transect (1×50m) was marked off, and using a 1×1m quadrat with 10cm×10cm subdivisions and scuba gear, the cover, colony size, and distribution data were collected. Data were analyzed in relation to seawater temperature and Sakurajima volcanic ash-fall data. It is most likely that abnormally high observed seawater temperatures (almost 30°C) in the summer of 1998 had a detrimental effect on the subject Zoanthus. In addition, it is conceivable that irregular scattered volcanic ash fall may also have a detrimental effect.

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To study morphological changes in zooxanthellae in bleached corals, we observed zooxanthellae in colonies of Acropora nasuta that suffered various degrees of bleaching. Colonies were collected from a shallow reef at Bise, Okinawa, from July to September in 2001. Zooxanthellae within the tissue of A. nasuta were classified into 3 types based on their coloration and shape: healthy-looking zooxanthellae (Hz.), pale zooxanthellae (Pz.) and transparent zooxanthellae (Tz.). The Pz. were pale yellow with more or less disorganized cellular content, while Tz. were swelled and vacuolated with no pigmentation. Tz. were the dominant zooxanthellae in colonies that suffered severe bleaching, while non-bleached colonies and those recovered from bleaching had mostly Hz. Some Tz, were ruptured with vacuoles spreading out of the cell. The density of zooxanthellae in severely bleached colonies was about 10⁵ cells cm^-2. The present observation suggests that, during natural bleaching due to chronic stress, zooxanthellae remained in host tissue lose pigmentation and become swelled and vacuolated suggesting necrotic death of the zooxanthellae.

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The purpose of this paper is to reveal coral reef and mangrove landscapes for pastoralists of the arid tropics, based on a case analysis of place names on Sudanese Red Sea coast. I have interviewed five informants of the Beja around 'Agetai village on Sudanese Red Sea coast. They gave me forty-five place names, and explained or interpreted those names.
They named “intestines of dogs” for the long and narrow part of the particular island and the attached coral reef flat where local people can cross by riding on camels carefully. On the other hand, they named “horns of gazelles” for the high trees of mangroves along the shoreline of the island which were left over by cutting down its branches and foliage for camel forage. They compare coral reef and mangrove landscapes to body parts of dogs and gazelles that they either take care of or hunt. Therefore, Is can characterize that they replace the physical and biological environments at macro-level in the sea (coral reef and mangrove landscapes) for biological environments at micro-level on the land (particular body parts of domesticated animals and wild animals). However, they do not have any general names (classified categories) for topographical features of coral reef.

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Coral reef fisheries resources in the Pacific Islands, Southeast Asia and Okinawa have decreased recently. Coral reef and mangrove eco-system supporting the resources is also in the threat. The fisheries resources, in essence, need proper management because the resources are renewable and considered common property. Typical conditions for tropic fisheries management are many species, many remote islands, few researchers, many subsistence fisheries, and a strong sense of community. Under these conditions the management regimes that have evolved in Western developed countries have seldom worked properly. Instead, considering efficient compliance and enforcement, the resources should be managed through partnership between the government and the communities (co-management). The resources may be managed more efficiently by a retrospective approach than a pre-emptive approach. Among management tools (e. g. seasonal closure, size limit, gear restriction, catch quota, license, etc.), Marine Protected Area (MPA) seems most effective. In Samoa and Okinawa, co-management of nearshore resources has been implemented with fisheries extension programs in analogous ways. Both cases have seemed successful to date. In the past, the Philippines was infamous for destructive fisheries, but now many successful cases of co-management have appeared with the help of NGOs and international research organizations.

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