To examine whether damage to zooxanthellar photosystem II (PSII) is the primary step of thermally induced coral bleaching, we first assessed the relationship between the maximum quantum yield of PSII (F_v/F_m) or active PSII centers (F_v/F_o) and maximum electron transport rate (ETR_max), which represent the PSII activity and electron flow beyond the PSII, respectively, in the symbiotic algae of the coral Pachyseris rugosa. Next, the photo-physiological responses of the symbionts to stress treatments of 1h high temperature (33.5°C) and/or high light (1030μmol quanta m^-2 s^-1) stress and 6h recovery were investigated. The 1h high temperature treatment in darkness produced a significant, but reversible (6h recovery) decline in ETR_max without any change in F_v/F_m. The 1h high light treatment reduced F_v/F_m, but not ETR_max. High temperature in combination with high light resulted in a more pronounced reduction in F_v/F_m, along with a significant decline in ETR_max. Neither F_v/F_m nor ETR_max recovered fully within 6h. Reversible increases in non-photochemical quenching (NPQ), energy dissipation in PSII, were also recorded. Chloramphenicol (CAP), an inhibitor of synthesis of D1 protein of PSII reaction center, revealed that a minimum of -60% of the F_v/F_m or -30% of active PSII centers (F_v/F_o) is required to maintain ETR_max in the in hospite symbionts. These results suggest that the primary step of heat-induced damage in the symbiont's photosynthetic apparatus involves a component beyond the PSII, probably at the level of the dark reaction as indicated by reduced ETR_max and the PSII damage is secondary.

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Red soil contamination into marine ecosystems such as coral reefs and estuaries is a prevalent environmental problem in the Okinawa Islands. This study was conducted to examine the chemical impact of Okinawan red soil on seawater. The different soil weights were mixed and shaken with 100mL of seawater for four hours to obtain the extracts. The pH, concentrations of Na⁺, K⁺, Ca²⁺, Mg²⁺, Al³⁺ and dissolved silica were then determined. The soil is acidic with a pH value of 5.03, dominated by SiO₂ and Al₂O₃. The pH of the Zampa cape seawater was 8.23 and decreased with soil weight to the lowest value of 4.06. The Al concentration in the seawater was 0.0256meqL^-1 and increased with soil to solution ratio to the maximum value of 5.95meqL^-1. The base metal concentrations decreased from the seawater by 23.5%, 8.04%, and 3.59% in extracts for K⁺, Ca²⁺ and Mg²⁺, respectively, while Na⁺ was relatively stable to change. The dissolved SiO₂ increased from 0.430mgL^-1 in the seawater to the maximum value of 20.0mgL^-1 in ground soil. The Summation of decreasing K⁺, Ca²⁺ and Mg²⁺ concentrations and increasing Al³⁺ and H⁺ in the extracts showed a high correlation coefficient (P<0.001), which largely suggests an exchange process. The significant correlations between logarithmic concentrations of Al³⁺ and silica vs. pH (P<0.001) also suggest the importance of H⁺ to release soluble Al as well as hydrogen-promoted weathering of silicates. Physical features such as sedimentation and turbidity do affect coral reefs, but possibly chemical effects such as the elevated Al concentration observed in coastal seawaters may also interfere with the coral's well being at significant red soil-affected areas in the Okinawa Islands.

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A new genus of paralcyoniid soft corals (Octocorallia: Paralcyoniidae) from the Indo-West Pacific is described and named Ceeceenus. The new genus is compared with the related genera Paralcyonium Milne Edwards, 1850 and Studeriotes Thomson & Simpson, 1909. Four new species are described and included in the new genus. They were found in Thailand, Japan, Palau, Papua New Guinea and Tonga.

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Regeneration of artificial injuries on scleractinian corals of massive colonies Porites lutea and branching Porites cylindrica and algal/coral competition on newly formed substrate are the subject of investigation. It was shown that the injured coral areas recovered at three stages (1) coral tissue recovery with the formation of a border between the regenerating live tissue and dead area, (2) growth and expansion of the live tissue on the substrate, and (3) new polyps development on the healed area. At the first stage of the regeneration, the rate of lesion healing was highest; it varied in respect to injury type and averaged 0.2-0.05 and 0.1-0.02mm day^-1 for P. lutea and P. cylindrica, respectively. The regeneration rate mostly depended on morphology of corals and injury type. Coral entombed spores and thalli fragments of algae settled onto partially damaged live tissue and skeleton. At the second stage, the rate of lesion healing sharply decreased and varied from 0.1 to 0.03mm day^-1 for P. lutea and from 0.05 to 0.02mm day^-1 for P. cylindrica. Position of the injuries within the colony, light intensity, as well as the composition and abundance of algae and animals settled onto the damaged areas had a significant effect on the rate and duration of the recovery process. The algae growing on dead areas of the injuries acted as a physical and in rare cases as a chemical impediment for expansion of live tissue on the available substrate. At the second stage of healing, the live tissue overgrew twenty two algal species settled onto the lesions at winter and spring seasons. At the third stage of the regeneration, the recovery depended on external and internal conditions promoting the growth of coral polyps.

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The partial pressure of CO₂ in seawater and air-sea CO₂ flux were measured at the Sesoko coral reefs in Okinawa, Japan, and the effect of various perturbations on the gas exchange coefficient is discussed. The CO₂ flux varied from -1.0 to 1.3mmol m^-2h^-1, which corresponded with the variation in partial pressure of CO₂ in seawater. Atmospheric CO₂ was absorbed by seawater during the day and released at night. This was mainly because of community photosynthesis and respiration. The gas exchange coefficient obtained from the chamber method was relatively larger than the wind dependent gas exchange coefficient. In the present study, the gas exchange coefficient was 5 and 30 times higher than that reported by Wanninkhof (1992) and Liss and Merlivat (1986), respectively when the wind velocity was set to 2.8m s^-1. Our result (13.8±2.7cm h^-1) was close to that reported by Komori and Shimada (1995), which took into account both the effects of turbulence and wind velocity on the gas exchange coefficient, indicating that not only wind, but also the effects of turbulence and other factors are important in the coefficient estimation at the Sesoko coral reefs.

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Fish faunas and diets were examined in Halodule uninervis- and Syringodium isoetifolium-dominated seagrass beds at Mauritius, western Indian Ocean, in March 2002. A total of 37 fish species (representing 16 families) were collected, 26 (14 families) of them occurring in the H. uninervis-bed and 26 (13 families) in the S. isoetifolium-bed, with 15 (10 families) common to both beds. Fishes were mainly juveniles, dominant families with regard to both species and individual numbers being Apogonidae, Mullidae, Labridae, Scaridae and Gobiidae. Zoobenthivores comprised the most dominant feeding type in both seagrass beds, harpacticoid copepods and gammaridean amphipods being the most important food resources for those fishes.

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[in Japanese]

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