論文 - 藤村　弘行

Vegetation variety affected by local environments in a coral reef lagoon

Tozaki, K; Nishihara, GN; Kawate, A; Konishi, T; Sato, Y; Ito, M; Fujimura, H; Tanaka, A

PHYCOLOGICAL RESEARCH ( Phycological Research )  72 ( 2 ) 112 - 122   2024年04月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Abstract From shore to sea, coral reefs can generally be divided into a lagoon zone, a reef crest, and a fore reef. Environmental variables, such as nutrient fluxes, light availability, and water temperature, vary among the zones and influence the biodiversity of submerged macrophytes. Additionally, the biodiversity of vegetation within the lagoon appears to be affected by multiple and extremely localized conditions. We investigated the impact of small‐scale variations on vegetation diversity, and implemented an ecological survey within a well‐defined area inside of a lagoon at Bise Point, Okinawa, Japan. A total of 20 macroalgal species (four green algae, six brown algae, and ten red algae) and four seagrass species were identified from the surveyed quadrats over a period of 19 months, from October 2019 to March 2021. Patterns in species occurrence were spatially and temporally heterogeneous. Notably, water motion and sediment flux were highly variable among the monitoring sites. Redundancy analysis allowed us to evaluate the significance of environmental factors on the vegetation of each monitoring area. Six environmental factors were considered in this study, but their impacts on local vegetation were not equivalent. Redundancy analysis suggested that water depth, flow velocity, and the ratio of the small fraction of deposition particles were the three factors with the strongest influence on local vegetation. This study provides some crucial insights into the determinants of vegetation in a coral reef lagoon. Our findings suggest that the factors we examined exert more influence on the vegetation than seasonal effects.

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人的介入によるサンゴ礁保全策の現状と可能性—サンゴの白化に着目して—

樋口 富彦, 宮島 利宏, 高木 俊幸, 湯山 育子, アゴスティーニ シルバン, 中村 隆志, 藤村 弘行

日本サンゴ礁学会誌 ( 日本サンゴ礁学会 )  26 ( 1 ) 19 - 37   2024年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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<p>海水温上昇によるサンゴの白化の頻発が大きな問題となっており，将来的に広範囲でサンゴが死滅する可能性が示唆されている。近年，大規模な死滅からサンゴを救済することを目指した人的介入方法が検討され，現場での実現可能性を含め議論されている。本稿では，白化を防止・軽減する物理環境や経験環境履歴によるストレス耐性の獲得，外的な餌の供給による栄養の増強やマンガンなどの金属元素の付加によるストレス耐性強化に加え，細菌を含めたホロビオントとしての白化対策について紹介し，人的介入によるサンゴ礁生態系保全策の現状と今後の可能性について言及する。</p>

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Nutrient uptake characteristics of Cladosiphon okamuranus (Phaeophyceae) from the Ryukyu Islands of Japan

Yoichi Sato, Eri Inomata, Hikari Nagoe, Michihiro Ito, Teruko Konishi, Hiroyuki Fujimura, Atsuko Tanaka & Gregory N. Nishihara

Journal of Applied Phycology ( Journal of Applied Phycology )  35 ( 1 ) 265 - 275   2023年02月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Correction: The Effect of Co-Culture of Two Coral Species on Their Bacterial Composition Under Captive Environments.

Ide K, Nakano Y, Ito M, Nishikawa Y, Fujimura H, Takeyama H

Marine biotechnology (New York, N.Y.) ( Marine Biotechnology )  24 ( 6 ) 1176 - 1176   2022年10月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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The Effect of Co-Culture of Two Coral Species on Their Bacterial Composition Under Captive Environments.

Ide K, Nakano Y, Ito M, Nishikawa Y, Fujimura H, Takeyama H

Marine biotechnology (New York, N.Y.) ( Marine Biotechnology )  24 ( 5 ) 871 - 881   2022年10月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Coral symbionts are important members of the coral holobiont, and coral bacterial flora are essential in host health maintenance and coral conservation. Coral symbionts are affected by various environmental factors, such as seawater temperature, pH, and salinity. Although physicochemical and chemical factors have been highlighted as possible causes of these effects, the effects of water flow and the co-culture of different species corals have not been elucidated. In this study, we designed an artificial rearing environment to examine the impact of environmental and biological factors on Acropora tenuis, one of the major coral species in Okinawa, and Montipora digitata, during their co-culture. We intervened with the water flow to reveal that the movement of the rearing environment alters the bacterial flora of A. tenuis. During the rearing under captive environment, the alpha diversity of the coral microbiota increased, suggesting the establishment of rare bacteria from the ocean. No differences in the bacterial composition between the control and water flow groups were observed under the rearing conditions. However, the structure of the bacterial flora was significantly different in the co-culture group. Comparison of bacterial community succession strongly suggested that the differences observed were due to the suppressed transmission of bacteria from the ocean in the co-culture group. These results enhance our understanding of interactions between corals and shed light on the importance of regional differences and bacterial composition of coral flora.

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Long-term trends and seasonal variations in environmental conditions in Sesoko Island, Okinawa, Japan

Singh Tanya, Sinniger Frederic, Nakano Yoshikatsu, Nakamura Shigeo, Kadena Shouhei, Jinza Mori, Fujimura Hiroyuki, Harii Saki

Galaxea, Journal of Coral Reef Studies ( 日本サンゴ礁学会 )  24 ( 1 ) 121 - 133   2022年01月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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<p>Knowledge of environmental factors is crucial in understanding biological and ecological processes. Yet information on the environment around Sesoko Island, Okinawa, Japan, one of the main locations for coral reef research in Japan, remains scarce. Data of air and sea surface temperature (SST), wind velocity, wave height, and frequency of typhoons have been manually recorded at Sesoko Station, Tropical Biosphere Research Station, the University of the Ryukyus from September 1990 to November 2021. Here we describe the seasonal and long-term trends in these environmental variables at Sesoko Island. Some of the key findings were that the air temperature and SST fluctuated by ~9-12°C throughout the year. A rise in air temperature and SST between 1990 and 2021 was observed in the winter and autumn season, respectively. The Degree Heating Week (DHW) based on the in-situ data reflected the bleaching observations around Sesoko Station. The DHW exceeded the critical bleaching level of 8°C-week in 1998 and the significant bleaching level of 4°C-week in 2001, 2016, and 2017. Weak southerly winds were dominant in summers, while stronger northeasterly winds were dominant in winters. The frequency of winds between 3.4 to 7.9 m/s and northeastern winds have increased through time. Typhoons generally occur between May and October, and the frequency of typhoons has not increased over the past 30 years. Wave heights never exceeded 0.5 m and were highest between July and September. These findings will provide a reliable baseline of the environment at Sesoko Island for further ecological studies.</p>

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Final yield of the brown alga Cladosiphon okamuranus (Chordariaceae, Phaeophyceae) may depend on nursery quality

Sato Y.

Phycological Research ( Phycological Research )  69 ( 3 ) 159 - 165   2021年07月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Cladosiphon okamuranus (Chordariaceae, Phaeophyceae) production is an important economic activity in the islands of Okinawa, Japan, and has been unstable for the past decade. Local producers surmise that unstable yields are related to highly localized environmental conditions. We report that the differential yields of C. okamuranus harvested from experimental nets during the 2019 season at two adjacent nurseries (less than 40 m apart), which were designated as a poor or good nursery by local producers, were 137 and 253 kg (wet weight), respectively. In fact, nutrient conditions between the poor and good nursery were slightly different, although involvement of some unsurveyed environmental factors cannot be excluded at present. Additionally, we report on a thallus shearing phenomenon that led to the catastrophic loss of thalli from the cultivation nets.

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Photooxidation Products from a Marine Cadinane Sesquiterpenoid

Kurnianda Viqqi, Fujimura Hiroyuki, Kanna Yoko, Tanaka Junichi

Chemistry Letters ( 公益社団法人 日本化学会 )  50 ( 2 ) 220 - 222   2021年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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<p>To show that artifacts can readily form during research on marine natural products, a common marine sesquiterpenoid <b>1</b> was treated with sunlight in the presence of a pigment. Another set of solutions were prepared and kept in shade under the bench for two weeks as negative controls. As a result, four oxygenated derivatives <b>2</b>–<b>5</b> were obtained. A unique structure of a highly oxidized molecule <b>5</b> was solved by X-ray crystallography.</p>

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A metabarcoding survey for seasonal picophytoplankton composition in two coral reefs around Sesoko Island, Okinawa, Japan

Handung Nuryadi, Thi Tra My Nguyen, Michihiro Ito, Naoko Okada, Satoshi Wakaoji, Toru Maruyama, Yoshikatsu Nakano, Hiroyuki Fujimura, Haruko Takeyama, Shoichiro Suda

Journal of Applied Phycology ( Journal of Applied Phycology )  30 ( 6 ) 3179 - 3186   2018年12月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Chemical and biological characteristics of Albion reef in the South-West of Mauritius Island with special reference to primary production and N2 fixation of benthic substrata

Beatriz E. Casareto, Ranjeet Bhagooli, Hiroyuki Fujimura, Yoshimi Suzuki

Western Indian Ocean Journal of Marine Science   Special Issue 1   85 - 93   2017年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Mitochondrial electron transport activity and metabolism of experimentally bleached hermatypic corals

Sylvain Agostini, Hiroyuki Fujimura, Hiroyuki Hayashi, Kazuhiko Fujita

Journal of Experimental Marine Biology and Ecology ( ELSEVIER SCIENCE BV )  475   100 - 107   2016年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Bleached corals (Porites cylindrica and Galaxea fascicularis) were obtained through extended incubation (over 45 days) under light depletion and privation: low light and dark conditions, and heat stress (32 degrees C). The colonies in the different treatments became bleached and had reduced metabolic rates, photosynthesis, calcification and respiration; reduced biomass, zooxanthellae density, and chlorophyll a concentrations; and reduced mitochondrial electron transport system activity, which represent potential respiration rates. The most important reduction in mitochondrial electron transport activity was shown when the activities were normalized by the unit of surface and not by the unit of host protein. This result indicates that the reduction in activity could be mainly explained by the reduction of biomass and tissue thickness. However, increased Manganese Superoxide dismutase (Mn SOD) activity, a mitochondrial SOD, suggests that ROS production occurs in the mitochondria under heat stress with the consequence of potentially damaging the electron transport system. The reduced calcification rates observed are hypothesized to be the results of a decrease in the energy available for calcification due to the reduced photosynthetic rates, limiting the availability of substrates for respiration and therefore the energy production, and the decreased in the number of active mitochondrial electron transport system. Electron transport system activity associated with respiration is the basis of all metabolic processes and is not biased by incubation like traditional measurements of respiration in an aquarium. Therefore, ETSA could be used as an overall indicator of coral health, especially for host animal health. (C) 2015 Elsevier B.V. All rights reserved.

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Response of subtropical coastal sediment systems of Okinawa, Japan, to experimental warming and high pCO2

Rumana Sultana, Beatriz E. Casareto, Rumi Sohrin, Toshiyuki Suzuki, Md. Shafiul Alam, Hiroyuki Fujimura, Yoshimi Suzuki

Frontiers in Marine Science ( Frontiers Media S. A )  3 ( JUN ) 100   2016年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Increasing seawater temperatures and CO2 levels associated with climate change affect the shallow marine ecosystem function. In this study, the effects of elevated seawater temperature and partial pressure of CO2 (pCO2) on subtropical sediment systems of mangrove, seagrass, and coral reef lagoon habitats of Okinawa, Japan, were examined. Sediment and seawater from each habitat were exposed to four pCO2-temperature treatments, including ambient pCO2- ambient temperature, ambient pCO2-high temperature (ambient temperature + 4°C), high pCO2 (936 ppm)-ambient temperature, and high pCO2-high temperature. Parameters including primary production, nutrient flux, pigment content, photosynthetic community composition, and bacterial abundance were examined. Neither high temperature nor high pCO2 alone impacted mangrove and seagrass sediment primary production significantly (Tukey's test, P &gt 0.05). However, the combined stress significantly (Tukey's test, P &lt 0.01) increased primary production in these two habitats. In sediments from the coral reef lagoon, single and combined stress treatments induced a shift from heterotrophy to autotrophy. Significant increases in net primary production (Tukey's test, P &lt 0.01), and gross primary production (Tukey's test, P &lt 0.05) under the combined stress suggested that benthic microalgae in mangrove and seagrass sediments were more responsive to high temperature and pCO2 conditions than those in coral reef lagoon sediments. Additionally, combined stress significantly increased the sediment chlorophyll a content (Tukey's test, P &lt 0.05) in all habitats. These increases were associated with increased net primary production, indicating that combined stress stimulates primary production activity by the photosynthetic benthic microalgae in all habitats. Diatom activity increased, as silicate uptake increased in all habitats. Microbial abundance significantly increased under the combined stress treatment (Tukey's test, P &lt 0.01), but did not exceed autotrophic activity. Respiration did not change significantly in any of the three habitats (Tukey's test, P &gt 0.05) under the combined stress, suggesting that heterotrophic processes were less affected by the combined stress than autotrophic processes. In summary, mangrove and seagrass sediments minimize the negative impacts of elevated temperature and pCO2 via increased primary production and carbon storage. Lagoonal sediments also act as a carbon sink under temperature and ocean acidificationstress.

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Geochemistry of two shallow CO<inf>2</inf> seeps in Shikine Island (Japan) and their potential for ocean acidification research

Sylvain Agostini, Shigeki Wada, Koetsu Kon, Akihito Omori, Hisanori Kohtsuka, Hiroyuki Fujimura, Yasutaka Tsuchiya, Toshihiko Sato, Hideo Shinagawa, Yutaro Yamada, Kazuo Inaba

Regional Studies in Marine Science ( Regional Studies in Marine Science )  2   45 - 53   2015年11月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Shallow CO2 seeps, where CO2 gas is venting underwater, offer great potential for studies into the effects of ocean acidification at the ecosystem level. To our knowledge, only two tropical system and two temperate systems of such seeps have been described worldwide. Here we describe two new temperate systems: the Mikama Bay and Ashitsuke sites, located on Shikine Island, Japan. The Mikama Bay site is located in a shallow bay. Investigation of the gas and water chemistry showed that the gas contained 98% CO2 and up to 90 ppm H2S. Total alkalinity was constant in time and space with an average of 2265 +/- 10 mu mol kg(-1). Mapping of Eh and pH showed that the low pH zones were the largest when currents were moderate. Under moderate currents, Eh values were globally higher and total sulfides concentration lower, supporting that a longer residence time of the bay water allow the oxidation of the sulfides to sulfates. Zones suitable for acidification studies: with a pH lower than 8.0, low saturation state of calcite and aragonite, and non-detectable sulfide concentration, can be defined a few meters from the main venting zone. The second site, Ashitsuke, is located in the inter-tidal zone on a shore composed of boulders. Several areas showed reduced pH sometimes restricted to a few meters and up to 20 m long along the shoreline. Temperature was higher in some of the reduced pH zones suggesting the presence of hot springs in addition to vents. This paper also highlights the need for discovering additional CO2 seeps, which by their nature often lack comparable replicates and can be confounded by factors other than CO2. In this regard, Japan offers great potential as it is home to numerous active volcanoes, representing potential venting sites in climates ranging from tropical to sub-polar. (C) 2015 Elsevier B.V. All rights reserved.

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The Nutrient and Carbon Dynamics that Mutually Benefit Coral and Seagrass in Mixed Habitats under the Influence of Groundwater at Bise Coral Reef, Okinawa, Japan

Higuchi, T, Takagi, K.K, Matoba, K, Kobayashi, S, Tsurumi, R, Arakaki, S, Nakano, Y, Fujimura, H, Oomori, T, Tsuchiya, M

International Journal of Marine Science   4 ( 1 ) 1 - 15   2014年01月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

The Nutrient and Carbon Dynamics that Mutually Benefit Coral and Seagrass in Mixed Habitats under the Influence of Groundwater at Bise Coral Reef, Okinawa, Japan

Higuchi, T., Takagi, K.K., Matoba, K., Kobayashi, S., Tsurumi, R., Arakaki, S., Nakano, Y., Fujimura, H., Oomori, T. and Tsuchiya, M.

International Journal of Marine Science ( その他の出版社 )  4 ( 1 ) 1 - 15   2014年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

Characterization of the proteinaceous skeletal organic matrix from the precious coral, Corallium konojoi

Rahman, M.A., Karl, K., Nonaka, M., Fujimura, H., Shinjo, R., Oomori, T. and Wörheide, G.

Proteomics ( その他の出版社 )  14 ( 21-22 ) 2600 - 2606   2014年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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The Japanese red and pink corals are known to be precious because of their commercial value resulting from their use in ornaments, jewelry, and medicine. Precious corals are very interesting models for biomineralization studies and possess two different skeletal structures: an axial skeleton and an endoskeleton (sclerites). Although it has long been known that the organic matrix proteins existing in coral skeletons are critical for the oriented precipitation of CaCO3 crystals, these proteins in moderate deep-sea Japanese precious corals remain uncharacterized. Therefore, in this study, we performed skeletal whole proteome analyses using 1D and 2D electrophoresis, nano-LC, and MALDI-TOF-TOF MS. We identified a total of 147 functional coral skeletal organic matrix proteins (120 from the sclerites and 36 from the axial skeleton), including two calcium-binding calmodulin. Among the organic matrix proteins identified, nine key proteins are highly typical and common in both skeletons. Strong glycosylation activity, which is essential for skeletal formation in calcifying organisms, was detected in both skeletons. This work demonstrates unique biomineralization-related proteins in precious corals and provides the first description of the major proteinaceous components of CaCO3 minerals in precious corals, enabling the comparative investigation of biocalcification in other octocorals.

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Biotic Control of Skeletal Growth by Scleractinian Corals in Aragonite–Calcite Seas.

Higuchi, T., Fujimura, H., Yuyama, I., Harii, S., Agostini, S. and Oomori, T.

PLoS ONE ( その他の出版社 )  9 ( 3 ) e91021   2014年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Modern scleractinian coral skeletons are commonly composed of aragonite, the orthorhombic form of CaCO3. Under certain conditions, modern corals produce calcite as a secondary precipitate to fill pore space. However, coral construction of primary skeletons from calcite has yet to be demonstrated. We report a calcitic primary skeleton produced by the modern scleractinian coral Acropora tenuis. When uncalcified juveniles were incubated from the larval stage in seawater with low mMg/Ca levels, the juveniles constructed calcitic crystals in parts of the primary skeleton such as the septa; the deposits were observable under Raman microscopy. Using scanning electron microscopy, we observed different crystal morphologies of aragonite and calcite in a single juvenile skeleton. Quantitative analysis using X-ray diffraction showed that the majority of the skeleton was composed of aragonite even though we had exposed the juveniles to manipulated seawater before their initial crystal nucleation and growth processes. Our results indicate that the modern scleractinian coral Acropora mainly produces aragonite skeletons in both aragonite and calcite seas, but also has the ability to use calcite for part of its skeletal growth when incubated in calcite seas.

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Multiple effects of hydrogen peroxide and temperature on antioxidants and bleaching

Higuchi,T., Suzuki,Y and Fujimura H

Proceedings of the 12th International Coral Reef Symposium ( International Coral Reef Society )    4C_3   2013年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

The effects of thermal and high-CO2 stresses on the metabolism and surrounding microenvironment of the coral Galaxea fascicularis

Agostini, S., Fujimura, H., Higuchi, T., Yuyama, I., Casareto, B.E., Suzuki, Y. and Nakano, Y.

Comptes Rendus Biologies ( その他の出版社 )  336 ( 8 ) 384 - 391   2013年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Respiratory electron transport system activity in symbiotic corals and its link to calcification

Agostini, S., Fujimura, H., Fujita, K., Suzuki, Y. and Nakano Y.

Aquatic Biology ( その他の出版社 )  18 ( 2 ) 125 - 139   2013年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Scleractinian corals host photosynthetic endosymbionts, making direct measurement of the host respiration rate via incubation methods based on O2 consumption impossible. We tested the use of the respiratory electron transport system activity (ETSA) for measuring host potential respiration. The applied method, modified from a previous study, is based on the re - duction of (4-iodophenyl)-3-(4-nitrophenyl)-5-phenyl-2H-tetrazolium chloride (INT) to formazan. After the development of a protocol suitable for corals, the method was tested on 5 different species. Metabolism, including photosynthesis, dark respiration and light and dark calcification, was measured through incubation. Host and zooxanthellae fractions were separated and their ETSAs, protein contents and zooxanthellae densities were measured. Mean ETSA/dark respiration (ETSA/R) ratios for host corals ranged from 1.7 ± 0.2 to 3.5 ± 0.6, while ratios for zooxanthellae ranged from 3.7 to 7.8. The high ratios observed for zooxanthellae indicate that their respiration may be 5 times higher under light conditions than in the dark. Considering the obtained ratios, host respiration in light could increase at most by a factor of 3.5 compared with dark respiration rates. Ratios close to 1 were found for some specimens, which suggests that higher respiration rates under light compared with dark conditions are not possible. Therefore, increased respiration in light cannot explain the observed enhancement of calcification under light conditions. ETSA was correlated with zooxanthellae density, suggesting adaptation of the levels of host ETS enzymes to the amount of translocated photosynthetates under optimal conditions. Estimated dark host respiration was correlated with photosynthesis, which suggests that it is determined mainly by the amount of energy available but also the amount of electron transport system enzymes. This constrains the amount of ATP available for calcification. Hence, we propose a mechanism by which respiration limits the calcification rate. © Inter-Research 2013.

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Bacterial enhancement of bleaching and physiological impacts on the coral Montipora digitata

Higuchi T, Agostini A, Casareto BE, Yoshinaga K, Suzuk T, Nakano Y, Fujimura H and Suzuki Y

Journal of Experimental Marine Biology and Ecology ( その他の出版社 )  440   54 - 60   2013年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Multiple effects of hydrogen peroxide and temperature on antioxidants and bleaching

Higuchi,T, Suzuki,Y, Fujimura H

Proceedings of the 12th International Coral Reef Symposium     4C_3   2012年06月 [ 査読有り ]

掲載種別: 研究論文（国際会議プロシーディングス）

Biological and Chemical Characteristics of the Coral Gastric Cavity

Agostini S, Suzuki Y, Higuchi T, Casareto BE, Yoshinaga K, Nakano Y and Fujimura H

Coral Reefs ( International Coral Reef Society )  31 ( 1 ) 147 - 156   2012年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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All corals have a common structure: two tissue layers enclose a lumen, which forms the gastric cavity. Few studies have described the processes occurring inside the gastric cavity and its chemical and biological characteristics. Here, we show that the coral gastric cavity has distinct chemical characteristics with respect to dissolved O-2, pH, alkalinity, and nutrients (vitamin B-12, nitrate, nitrite, ammonium, and phosphate) and also harbors a distinct bacterial community. From these results, the gastric cavity can be described as a semi-closed sub-environment within the coral. Dissolved O-2 shows very low constant concentrations in the deepest parts of the cavity, creating a compartmentalized, anoxic environment. The pH is lower in the cavity than in the surrounding water and, like alkalinity, shows day/night variations different from those of the surrounding water. Nutrient concentrations in the cavity are greater than the concentrations found in reef waters, especially for phosphate and vitamin B-12. The source of these nutrients may be internal production by symbiotic bacteria and/or the remineralization of organic matter ingested or produced by the corals. The importance of the bacteria inhabiting the gastric cavity is supported by the finding of a high bacterial abundance and a specific bacterial community with affiliation to bacteria found in other corals and in the guts of other organisms. The findings presented here open a new area of research that may help us to understand the processes that maintain coral health.

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Distribution and Potential Effects of Novel Antifouling Herbicide Diuron on Coral Reefs

Sheikh MA, Oomori T, Fujimura H, Higuchi T, Imo T, Akamatsu A, Miyagi T, Yokota T, Yasumura S

■■■     2012年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

Extracellular matrix protein in calcified endoskeleton: a potential additive for crystal growth and design

Rahman MA, Fujimura H, Shinjo R and Oomori T

Journal of Crystal Growth ( その他の出版社 )  324 ( 1 ) 177 - 183   2011年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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In this study, we demonstrate a key function of extracellular matrix proteins (ECMPs) on seed crystals, which are isolated from calcified endoskeletons of soft coral and contain only CaCO3 without any living cells. This is the first report that an ECMP protein extracted from a marine organism could potentially influence in modifying the surface of a substrate for designing materials via crystallization. We previously studied with the ECMPs from a different type of soft coral (Sinularia polydactyla) without introducing any seed crystals in the process, which showed different results. Thus, crystallization on the seed in the presence of ECMPs of present species is an important first step toward linking function to individual proteins from soft coral. For understanding this interesting phenomenon, in vitro crystallization was initiated in a supersaturated solution on seed particles of calcite (I 0 4) with and without ECMPs. No change in the crystal growth shape occurred without ECMPs present during the crystallization process. However, with ECMPs, the morphology and phase of the crystals in the crystallization process changed dramatically. Upon completion of crystallization with ECMPs, an attractive crystal morphology was found. Scanning electron microscopy (SEM) was utilized to observe the crystal morphologies on the seeds surface. The mineral phases of crystals nucleated by ECMPs on the seeds surface were examined by Raman spectroscopy. Although 50 mM Mg2+ is influential in making aragonite in the crystallization process, the ECMPs significantly made calcite crystals even when 50 mM Mg2+ was present in the process. Crystallization with the ECMP additive seems to be a technically attractive strategy to generate assembled micro crystals that could be used in crystals growth and design in the Pharmaceutical and biotechnology industries. (C) 2011 Elsevier B.V. All rights reserved.

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Seawater temperature proxies based on DSr, DMg, and DU from culture experiments using the branching coral Porites cylindrica

Armid A, Asami R, Fahmiati T, Sheikh, MA, Fujimura H, Higuchi T, Taira E, Shinjo R and Oomori T

Geochimica et Cosmochimica Acta ( その他の出版社 )  75 ( 15 ) 4273 - 4285   2011年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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In order to investigate the incorporation of Sr, Mg, and U into coral skeletons and its temperature dependency, we performed a culture experiment in which specimens of the branching coral (Porites cylindrica) were grown for 1 month at three seawater temperatures (22, 26, and 30 degrees C). The results of this study showed that the linear extension rate of P. cylindrica has little effect on the skeletal Sr/Ca, Mg/Ca, and U/Ca ratios. The following temperature equations were derived: Sr/Ca (mmol/mol) = 10.214(+/- 0.229) 0.0642(+/- 0.00897) x T (degrees C) (r(2) = 0.59, p < 0.05); Mg/Ca (mmol/mol) = 1.973(+/- 0.302) + 0.1002 (+/- 0.0118) x T (degrees C) (r(2) = 0.67, p < 0.05); and U/Ca (mu mol/mol) = 1.488(+/- 0.0484) - 0.0212(+/- 0.00189) x T (degrees C) (r(2) = 0.78, p < 0.05). We calculated the distribution coefficient (D) of Sr, Mg, and U relative to seawater temperature and compared the results with previous data from massive Porites corals. The seawater temperature proxies based on D calibrations of P. cylindrica established in this study are generally similar to those for massive Porites corals, despite a difference in the slope of D-U calibration. The calibration sensitivity of D-Sr, D-Mg, and D-U to seawater temperature change during the experiment was 0.64%/degrees C, 1.93%/degrees C, and 1.97%/degrees C, respectively. These results suggest that the skeletal Sr/Ca ratio (and possibly the Mg/Ca and/or U/Ca ratio) of the branching coral P. cylindrica can be used as a potential paleothermometer. (C) 2011 Elsevier Ltd. All rights reserved.

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CNP budgets of a coral-dominated fringing reef at La Re´union, France: coupling of oceanic phosphate and groundwater nitrate

Cuet P, Atkinson MJ, Blanchot J, Casareto BE, Cordier E, Falter J, Frouin P, Fujimura H, Pierret C, Susuki Y and Tourrand C

Coral Reefs ( International Coral Reef Society )  30 ( S.I. Suppl.1 ) 45 - 55   2011年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Productivity, nutrient input, nutrient uptake, and release rates were determined for a coral-dominated reef flat at La R,union, France, to assess the influence of groundwater nitrogen on carbon and nutrient budgets. Water samples were collected offshore in the ocean, at the reef crest and back reef for nutrients, picoplankton, pH, and total alkalinity. Volume transport of ocean water across the reef flat was measured using both current meters and drogues. Groundwater advected onto the reef flat and mixed with incoming ocean water. Metabolic rates for the reef community were determined to be: gross primary production = 1,000 mmol C m(-2) d(-1), community respiration = 960 mmol C m(-2) d(-1), and community calcification = 210 mmol C m(-2) d(-1). Across the reef flat, silicate behaved conservatively, there was net uptake of phosphate (0.06 mmol P m(-2) d(-1)) and net release of nitrate, ammonia, dissolved and particulate organic nitrogen (total 7.0 mmol N m(-2) d(-1)). Groundwater nitrate contributed 37% of the increase in nitrate plus ammonia. The first-order mass transfer coefficient of phosphate was 3.3 m d(-1), and for nitrate plus ammonia, 5.9 m d(-1). Gross N and P uptake from estimates of mass transfer and uptake of particles were 0.37 mmol P m(-2) d(-1) and 7.2 mmol N m(-2) d(-1), respectively giving an N:P uptake ratio of 20:1. Thus, the elevation of nitrogen across the reef flat maintains a high N:P flux, enhancing algal growth downstream of the transect. We conclude that net community production (40 mmol C m(-2) d(-1)) was sustained by net uptake of phosphate from the ocean and net uptake of new nitrogen from groundwater.

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Photochemical Formation of Hydroxyl Radicals in Tissue Extracts of the Coral Galaxea fascicularis

Higuchi T, Fujimura H, Hitomi Y, Arakaki T, Oomori T and Suzuki Y

Photochemistry and Photobiology ( その他の出版社 )  86 ( 6 ) 1421 - 1426   2010年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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サンゴ礁での石灰化と陸域の風化作用による島喚系の二酸化炭素収支

津留見　遼太,小林　秀星,樋口　富彦,大森　保,タカギ　キンバリー K.,新垣　誠司,土屋, 誠,

COE報告書（平成20年度） ( 琉球大学21世紀COEプログラム )    2009年04月

掲載種別: 研究論文（その他学術会議資料等）

　概要を見る

琉球大学21世紀COEプログラム「サンゴ礁島嶼系の生物多様性の総合解析」平成20年度成果発表会（平成21年3月14日開催）　講演・特別講演会場：理系複号棟102号室，ポスター発表会場：琉球大学50周年記念館1F （管理者追加）リポジトリ登録情報を移行しました。確認のうえ、加除修正をしてください。

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Effects of carbon dioxide on the coccolithophorid Pleurochrysis carterae in incubation experiments

Casareto BE, Niraula MP, Fujimura H and Suzuki Y

Aquatic Biology ( その他の出版社 )  7 ( 1-2 ) 59 - 70   2009年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Production (abundance and biomass) and net calcification rates of the coccolithophorid Pleurochrysis carterae under different partial pressures of CO2 (pCO(2)) were examined using short (15, 24 and 39 h), long (7 d) and dark (7 d) incubation experiments. Short incubations were conducted at ambient, 500 and 820 ppm pCO(2) levels in natural seawater that was enriched with nutrients and inoculated with P. carterae. Long incubations were conducted at ambient and 1200 ppm pCO(2) levels in natural seawater (0.2 mu m filtered as well as unfiltered) that was enriched with nutrients and inoculated with P. carterae. Dark incubations were conducted at ambient and 1200 ppm pCO(2) in unfiltered seawater that was inoculated with P. carterae. The abundance and biomass of coccolithophorids increased with pCO(2) and time. The abundance and biomass of most noncalcifying phytoplankton also increased, and were hardly affected by CO2 inputs. Net calcification rates were negative in short incubations during the pre-bloom phase regardless of pCO(2) levels, indicating dissolution of calcium carbonate. Further, the negative values of net calcification in short incubations became less negative with time. Net calcification rates were positive in long incubations during blooms regardless of pCO(2) level, and the rate of calcification increased with pCO(2). Our results show that P. carterae may adapt to increased (similar to 1200 ppm) pCO(2) level with time, and such increase has little effect on the ecology of noncalcifying groups and hence in ecosystem dynamics. In dark incubations, net calcification rates were negative, with the magnitude being dependent on pCO(2) levels.

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Detection and ecological threats of PSII herbicide diuron on coral reefs around the Ryukyu Archipelago, Japan

Sheikh MA, Fujimura H, Miyagi T, Uechi Y, Yokota T, Yasumura S, Oomori T

Marine Pollution Bulletin ( その他の出版社 )  58 ( 12 ) 1922 - 1926   2009年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Contamination and impacts of new antifouling biocide Irgarol-1051 on subtropical coral reef waters

Sheikh, M.A., Higuchi, T., Fujimura,H., Imo, T.S., Miyagi, T. and Oomori, T.

International Journal of Environmental Science and Technology ( その他の出版社 )  6 ( 3 ) 353 - 358   2009年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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U/Ca as a possible proxy of carbonate system in coral reef

Armid, A., Takaesu, Y., Fahmiati, T., Yoshida, S., Hanashiro, R., Fujimura,H., Higuchi, T., Taira, E. and Oomori, T.

Proceedings of the 11th International Coral Reef Symposium ( International Coral Reef Society )    92 - 96   2009年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

Activity of antioxidant enzymes (SOD and CAT) in the coral Galaxea fascicularis against increased hydrogen peroxide concentration in seawater

Higuchi, T., Fujimrua, H., Arakaki, T. and Oomori, T.

Proceedings of the 11th International Coral Reef Symposium ( International Coral Reef Society )    926 - 930   2009年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

The synergistic effects of hydrogen peroxide and elevated seawater temperature on the metabolic activity of the coral Galaxea fascicularis

Higuchi, T., Fujimura, H., Arakaki, T. and Oomori, T.

Marine Biology ( その他の出版社 )  156 ( 4 ) 589 - 596   2009年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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The effects of hydrogen peroxide on metabolism in the coral Goniastrea aspera

Higuchi, T., Fujimura, H., Ikota, H., Arakaki, T. and Oomori, T.

Journal of Experimental Marine Biology and Ecology ( その他の出版社 )  370 ( 1-2 ) 48 - 55   2009年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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コンクリート建造物に発生する鍾乳管の生成メカニズム

棚原朗, 山城理沙子, 宮崎美里, 藤村弘行

洞窟学雑誌 ( 日本洞窟学会 )  33   52 - 57   2008年12月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

U/Ca as a possible proxy of carbonate system in coral reef

Armid, A, Takaesu, Y, Fahmiati, T, Yoshida, S, Hanashiro, R, Fujimura,H, Higuchi, T, Taira, E, Oomori, T

Proceedings of the 11th International Coral Reef Symposium     92 - 96   2008年07月 [ 査読有り ]

掲載種別: 研究論文（国際会議プロシーディングス）

Activity of antioxidant enzymes (SOD and CAT) in the coral Galaxea fascicularis against increased hydrogen peroxide concentration in seawater

Higuchi, T, Fujimrua, H, Arakaki, T, Oomori, T

Proceedings of the 11th International Coral Reef Symposium     926 - 930   2008年07月 [ 査読有り ]

掲載種別: 研究論文（国際会議プロシーディングス）

コンクリート建造物に発生する鍾乳管の生成メカニズム

棚原朗、山城理沙子、宮崎美里、藤村弘行

洞窟学雑誌 ( 日本洞窟学会誌 )  33   52 - 57   2008年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

Distribution and possible impacts of toxic organic pollutants on coral reef ecosystems around Okinawa Island, Japan

Imo, S.T., Sheikh, M.A., Sawano, K., Fujimura, H. and Oomori, T.

Pacific Science ( その他の出版社 )  62 ( 3 ) 317 - 326   2008年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

　概要を見る

Organic pollutants have detrimental effects on the environment. In this study we evaluated the current status of contamination with organochlorine pesticides (OCPs), organo-tin compounds (OTCs), and polychlorinated biphenyls (PCBs) in the waters in and around Okinawa Island, Japan. Possible toxicological effects of these pollutants on marine life including corals are also discussed. Concentrations of total OCPs in river water were in the range of 1.02-56.4 ng liter(-1). Among the OCPs, alpha-BHC, beta-BHC, and aldrin were common in river water. OTCs detected in 30 samples of seawater were (mean +/- SD) monobutyl tin (MBT), 0.44 +/- 0.75 ng (Sri) liter(-1) dibutyl tin (DBT), 1.32 +/- 2.70 ng (Sri) liter(-1); tributyl tin (TBT), 0.72 +/- 2.90 ng (Sri) liter(-1); monophenyl tin (MPhT), 0.04 +/- 0.42 ng (Sri) liter(-1); diphenyl tin (DPhT), 0.007 ng (Sri) liter(-1); and triphenyl tin (TPhT), 0.013 ng (Sri) liter(-1). Highest concentrations of TBT, 28.5 ng (Sri) liter(-1) for water and 172 ng (Sn) g(-1) dry weight for sediment, were detected in samples from Itoman Port. Concentrations of total PCBs were 0.05-0.28 ng liter(-1) in open ocean and from 1.59 to 2.48 ng liter(-1) in coastal waters. Overall, this study shows that the coral reef ecosystems and their adjacent environments around Okinawa Island are contaminated by toxic organic contaminants (OCPs, OTCs, and PCBs). Levels of these contaminants detected in some sites have exceeded the Environmental Quality Target (EQT), which may pose a risk to health of marine life.

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Continuous-flow complete-mixing system for assessing the effects of environmental factors on colony-level coral metabolism

Fujimura, H., Higuchi, T., Shiroma, K., Arakaki, T., Hamdun, A.M., Nakano, Y. and Oomori, T

Journal of Biochemical and Biophysical Methods ( その他の出版社 )  70 ( 6 ) 865 - 872   2008年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Organic and inorganic carbon production by algal symbiont-bearing foraminifera on northwest pacific coral-reef flats

Fujita, K. and Fujimur, H.

Journal of Foraminiferal Researc ( その他の出版社 )  38 ( 2 ) 112 - 116   2008年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Algal symbiont-bearing benthic foraminifera are producers of both organic and inorganic carbon in coral-reef ecosystems. However, their contribution to the total budget of reef carbon production has not been adequately quantified. We used O-2-respirometry and alkalinity-anomaly techniques to estimate the organic and inorganic carbon production rates of three species of symbiont-bearing large foraminifera common to coral reef flats in the northwest Pacific Ocean. The species studied were Baculogypsina sphaerulata and Calearina gaudichaudii, which both harbor diatom endosymbionts, and Marginopora kudakajimensis, which harbors dinoflagellate endosymbionts. Live mature individuals were placed onto mesh in clear airtight containers filled with filtered seawater. The containers were incubated for several hours at a constant temperature and subjected to different levels of light intensity. Seawater was continuously mixed throughout the experiment. Dissolved oxygen, pH and total alkalinity were measured before and after incubation. Three species of larger benthic foraminifera were net organic and inorganic carbon producers. The P/R ratio exceeded 1 for all species. No photoinhibition was observed up to 1500 mu mol photons m(-2) s(-1), and calcification was enhanced by light. These findings suggest that the three species are net carbon producers adapted to high-light, reef-flat environments. In addition, we calculated that Baculogypsina sphaerulata and C. gaudichaudii together accounted for 2-7.5% of the gross primary production of a reef-crest community, whereas M. kudakajimensis supplied 1-11% of the gross primary production of a backreef community. The two calcarinids and M. kudakajimensis contributed similar to 1 and 10% of the inorganic carbon production of seaward reef flat and protected lagoon communities, respectively. Together with previous reports, these estimates suggest that algal symbiont-bearing foraminifera play a minor but essential role in the organic and inorganic carbon production of coral-reef ecosystems.

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［COE研究員の研究紹介］亜熱帯島嶼域におけるサンゴ礁生物群集代謝量の変遷と動態解析

その他の著者

No.1 (2005/7) ( 琉球大学21世紀COEプログラム広報委員会 )  ( 1 ) 10 - 10   2007年07月

掲載種別: 研究論文（その他学術会議資料等）

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（管理者追加）リポジトリ登録情報を移行しました。確認のうえ、加除修正をしてください。

亜熱帯島嶼域におけるサンゴ礁生物群集代謝量の変遷と動態解析

桑野　多恵子,樋口　富彦,新垣　雄光,大森　保,中野　義勝,

COE報告書（平成17年度） ( 琉球大学21世紀プログラム )    2007年07月

掲載種別: 研究論文（その他学術会議資料等）

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琉球大学21世紀プログラム「サンゴ礁島嶼系の生物多様性の総合解析」平成17年度成果発表会（平成18年3月6日開催）　会場：琉球大学大学会館3階 （管理者追加）リポジトリ登録情報を移行しました。確認のうえ、加除修正をしてください。

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チェンバー法による亜熱帯海域の底生生物群落の基礎生産量の評価

石川義朗、藤村弘行、鈴木款

Eco-Engineering ( 生態工学会誌 )  19 ( 3 ) 173 - 177   2007年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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A flexible closed chamber was applied to evaluate net primary production for three different benthic communities, which are coral, seagarass and micro-algae under the same experimental conditions at the Bisesaki, Okinawa, Japan in August, 2005. Study on the comparison among different communities at the same area, same tool and same condition is very few up to the present. A chamber was about 30 <I>l</I> for volume and 0.145 m<SUP>2</SUP> for bottom surface area. Net primary production and respiration were measured using dissolved oxygen sensor with temperature and salinity. Net primary productions were 37.0 &mu;mol<SUP>-1</SUP> h<SUP>-1</SUP> for coral community, 38.3 &mu;mol<SUP>-1</SUP> h<SUP>-1</SUP> for seagrass community and 14.6 &mu;mol<SUP>-1</SUP> h<SUP>-1</SUP> for benthic micro-community. These results indicate that net primary production of coral and seagrass communities is the almost same. It was confirmed that a use of same chamber is effective for comparison of the behavior of different living communities.

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Air-sea CO2 flux and gas exchange coefficient at the Sesoko coral reefs, Okinawa, Japan

Kitada, Y., Fujimura, H., Tokeshi, R. and Oomori, H.

Galaxea ( 日本サンゴ礁学会誌 )  8 ( 1 ) 51 - 60   2006年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

　概要を見る

沖縄県瀬底島のサンゴ礁において、大気-海水間のCO₂フラックスと海水中の二酸化炭素分圧を測定し、気体交換係数へのさまざまな撹乱の影響を議論した。CO₂フラックスは-1.0から1.3mmol m^-2h^-1まで変化し、海水中のCO₂分圧の変動と一致した。大気のCO₂は昼間に海水へ吸収され、夜間に放出された。これは、主に群集の光合成と呼吸によるものである。チャンバー法によって得られた気体交換係数は風速依存の気体交換係数に比べて大きかった。気体交換係数は風速を2.8m s^-1としたときに過去の研究 (Wanninkhof 1992; Liss and Merlivat 1986) で見積もられた値の5倍と30倍の高い値が本研究では得られた。我々の値は風速と乱流の両方の影響を考慮した Komori and Shimada (1995) に近い値が得られた。そして、そのことはサンゴ礁では風速の影響以外に乱流やその他の因子の影響が気体交換係数の見積もりに重要であるということを示している。

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Synthesis of Protodolomite from Coral Reef Sand

Fujimura, H., T. Oomori, S. Kochi, T. A. Prolla and S. Someya

Food Chemistry ( その他の出版社 )  99 ( 1 ) 15 - 18   2006年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Synthesis of protodolomite from coral reef sand

H Fujimura, T Oomori, S Kochi, TA Prolla, S Someya

FOOD CHEMISTRY ( ELSEVIER SCI LTD )  99 ( 1 ) 15 - 18   2006年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Protodolomite (calcium carbonate, PD) is widely used in calcium (Ca) and magnesium (Mg) nutritional supplements because it is rich in Ca (&gt; 20%) and Mg (&gt; 10%). Synthesis of PD usually involves the use of a NaCl solution with Ca2+ and Mg2+. In this study, we synthesized PD from coral reef sand (CRS) and magnesium chloride (MgCl2). First, CRS was dissolved in hydrogen chloride (HCl). MgCl2 was then added to the solution and the concentrations of Ca2+ and Mg2+ in the solution were adjusted to 150 and 350 mM. respectively. The solution was mixed with sodium carbonate (Na2CO3 = 156 mM) and incubated at 40 degrees C for 2 days in order to precipitate PD. The precipitate was identified as PD by X-ray diffraction analysis and atomic absorption analysis. This is the first study to synthesize PD from CRS. providing a new source of PD for the food industry. (c) 2005 Elsevier Ltd, All rights reserved.

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Air-sea CO2 Flux and Gas Exchange Coefficient at the Sesoko Coral Reefs, Okinawa, Japan.

藤村 弘行

Galaxea(Journal of Coral Reef Society of Japan) 8     51 - 60   2006年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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Simultaneous Measurement of Hydrogen Peroxide and Fe(II) in the Seawater Collected in Okinawa

Arakaki, T., H. Fujimura, A. M. Hamdun, K. Okada, H. Kondo, and T. Oomori

Journal of Oceanography ( 日本海洋学会誌 )  61 ( 3 ) 561 - 568   2005年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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The northern part of Okinawa Island suffers from red soil pollution - runoff of red soil into coastal seawater - which damages coastal ecosystems and scenery. To elucidate the impacts of red soil pollution on the oxidizing power of seawater, hydrogen peroxide (HOOH) and iron species including Fe(II) and total iron (Fe(tot), defined as the sum of Fe(II) and Fe(III)) were measured simultaneously in seawater from Taira Bay (red-soil-polluted sea) and Sesoko Island (unpolluted sea), off the northern part of Okinawa Island, Japan. We performed simultaneous measurements of HOOH and Fe(II) because the reaction between HOOH and Fe(II) forms hydroxyl radical (•OH), the most potent environmental oxidant. Gas-phase HOOH concentrations were also measured to better understand the sources of HOOH in seawater. Both HOOH and Fe(II) in seawater showed a clear diurnal variation, i.e. higher in the daytime and lower at night, while Fe(tot) cncentrations were relatively constant throughout the sampling period. Fe(II) and Fe(tot) concentrations were approximately 58% and 19% higher in red-soil-polluted seawater than in unpolluted seawater. Gas-phase HOOH and seawater HOOH concentrations were comparable at both sampling sites, ranging from 1.4 to 5.4 ppbv in air and 30 to 160 nM in seawater. Since Fe(II) concentrations were higher in red-soil-polluted seawater while concentrations of HOOH were similar, •OH would form faster in red-soil-polluted seawater than in unpolluted seawater. Since the major scavenger of •OH, Br-, is expected to have similar concentrations at both sites, red-soil-polluted seawater is expected to have higher steady-state •OH concentrations. Copyright © The Oceanographic Society of Japan.

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Ferrozine 試薬を用いる高速液体クロマトグラフィーによる沖縄島沿岸海水中の鉄(II)の光化学的挙動の研究

岡田孝一郎、中島仁美、藤村弘行、新垣雄光、棚原朗、大森保

分析化学 ( 日本分析化学会 )  54 ( 9 ) 861 - 867   2005年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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沖縄島沿岸海水中の全溶存鉄濃度｛Fe(II)＋Fe(III)｝と光化学によるFe(II) 生成についてFerrozine（FZ）試薬を用いて調べた．全溶存鉄濃度は，河川水の影響が大きい場所で最も高く，赤土土壌に汚染された海域では，清浄な海域よりも高かった．Fe(II) は，FZ試薬を用いた高速液体クロマトグラフィー（FZ-HPLC）法で調べた．既存のFZ-HPLC法を改良し，機器及び接続部にPoly Ether Ether Ketone（PEEK）樹脂を用いることで，計測機器からの汚染を抑えた．光照射実験の結果，Fe(II) の挙動は，3タイプに大別できた．Type Aは光照射時間にかかわらずFe(II) 濃度の変化が見られないタイプ，Type BはFe(II) 濃度が光照射直後増加するが，その後やや減少するタイプ，Type CはFe(II) 濃度が光照射時間とともに増加し，一定になるタイプである．Fe(II) の挙動は，Fe(III) 濃度，溶存有機物量，塩分などが影響していることが示唆された．また，光照射開始時点でFe(II) 濃度がゼロでなかったことから，沿岸海水中には溶存酸素や過酸化水素などに酸化されにくいFe(II) 化学種が存在することが明らかになった．<br>

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Ferrozine試薬を用いる高速液体クロマトグラフィーによる沖縄沿岸海水中の鉄((監))の光化学的挙動の研究

藤村 弘行, 新垣 武光, 棚原 朗, 大森 保

分析化学 54     861 - 867   2005年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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沖縄本島沿岸の海水中に光化学的に生成する過酸化物

中島仁美、岡田孝一郎、藤村弘行、新垣雄光、棚原朗

分析化学 ( 日本分析化学会 )  53 ( 9 ) 891 - 897   2004年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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沖縄島沿岸で採取した海水中で光化学的に生成する過酸化物を太陽光シミュレーターを用いて調べた．海水中で光化学反応により生成する過酸化水素の生成速度には一定のものと，減少していく2つのタイプが見られたが，有機過酸化物の光生成は見られなかった．沖縄の夏の太陽光強度に規格化した過酸化水素の光生成速度は，平均1.38±0.80 nM min^－1であった．過酸化水素の光生成初速度と溶存鉄イオン濃度及び300 nmにおける吸光度には，強い相関が見られたが，溶存有機炭素（DOC）濃度との相関は弱かった．海水中での過酸化水素の光生成に溶存有機化合物が関与していることはよく知られているが，溶存有機化合物濃度の指標となるDOC濃度との相関が弱かったことから，溶存している有機化合物の組成によって過酸化水素の光生成速度が異なることが示唆された．また，陸由来の成分が過酸化水素の光生成に関与していることが明らかになった．<br>

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How carbonate system in coral reef responds to global environmental change?

Oomori, T; Kitada, Y; Fujimura, H; Mori, M; Tokeshi, R; Noguchi, T; Taira, N; Sasaki, T

GEOCHIMICA ET COSMOCHIMICA ACTA   67 ( 18 ) A363 - A363   2003年09月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

Photochemical activity of seawater contaminated with red soil in the northern part of Okinawa

Hamdun, AM; Okada, K; Fujimura, H; Arakaki, T; Taira, H

GEOCHIMICA ET COSMOCHIMICA ACTA   67 ( 18 ) A131 - A131   2003年09月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

Carbon dioxide and air-sea CO<inf>2</inf> flux in coral reef

Fujimura H.

Mer ( Mer )  40 ( 3 ) 99 - 109   2002年08月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

サンゴ礁海域における二酸化炭素分圧と大気-海洋間のCO2フラックス

藤村弘行, 大森 保, 北田幸男, 真栄平 司

La Mar ( 日仏海洋学会 )  40 ( 3 ) 99 - 109   2002年08月 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

サンゴ礁海域における二酸化炭素分圧と大気-海洋間のCO2フラックス

藤村弘行、大森　保、北田幸男、真栄平　司

La Mar ( 日仏海洋学会誌 )  40   99 - 109   2002年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

Change of Coral Carbon Metabolism Influenced by Coral Bleaching

Fujimura, H., T. Oomori, T. Maehira, T. and Miyahira, K.

Galaxea ( 日本サンゴ礁学会誌 )  3 ( 3 ) 41 - 50   2001年 [ 査読有り ]

掲載種別: 研究論文（学術雑誌）

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塊状の造礁サンゴ <i>Favites sp.</i> と <i>Porites sp.</i> の生育するメソコズム (隔離水界) で1998年の白化現象の初期段階と後期段階における有機炭素生産量 (光合成-呼吸量) と無機炭素生産量 (石灰化-溶解量) を測定した。海水面では大気-海水間のCO₂フラックスを直接測定し、メソコズムでの炭素収支を算出した。<br>純有機炭素生産量は白化初期段階の15.8mmol m^-2 d^-1から白化後期段階の9.5mmol m^-2 d^-1に減少した。純無機炭素生産量は白化初期段階の11.2mmol m^-2 d^-1から白化後期段階の-7.0mmol m^-2 d^-1に激減した。これは昼間の石灰化量の減少と夜間の溶解量の増加によるものであり、炭酸塩の溶解を示す。大気-海水間のCO₂フラックスは白化初期段階が-1.8mmol m^-2 d^-1、白化後期段階が-1.1mmolm^-2 d^-1であり、どちらも大気から海水へCO₂が吸収された。<br>白化の初期段階と後期段階でP/R比 (=1.2) はほとんど変化しなかったことから、白化によって褐虫藻の光合成活性は変化しないことが示唆された。サンゴの白化により石灰化速度は光合成速度に較べ著しく減少した。白化はサンゴにダメージを与え、サンゴ-褐虫藻の共生系の炭素代謝に大きく影響した。

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