University of the Ryukyus · Faculty of Science · 教授

Research fieldsAnalytical chemistry・Environmental dynamic analysis・生態学、環境学

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• Estimation of bubbled oxygen flux from a coral reef community2025 · <p>We collected bubbles from the seafloor of coral reef areas to determine their quantity and chemical composition. The chemical composition was high in oxygen and low in carbon dioxide compared to that of the atmosphere. Oxygen fluxes to the atmosphere from coral reef waters are generally determined considering only dissolved oxygen in seawater, but accounting for bubbled oxygen increased such fluxes by about 70%. At the same time, the primary production rate in coral reefs is estimated only from the dissolved oxygen concentration in seawater, but accounting for bubbled oxygen increased it by about 20–30%. The composition of bubbled gases suggests that approximately 20% of the oxygen present may be derived from photosynthesis in the reef area. Global quantitative estimation of bubbled oxygen fluxes in tropical and subtropical coral reef waters remains critical for future research.</p>
• Can feeding be used for coral bleaching mitigation? Assessing the effect of using transcriptomics2025 · Yuyama, I; Yasuda, N; Higa, S; Yang, SY; Agostini, S; Higuchi, T; Miyajima, T; Nakamura, T; Furukawa, R; Mukaida, S; Fujimura, H
• Does coral community diversity increase microflora diversity and enhance environmental adaptation?2025 · Nakano, Y; Ide, K; Ito, M; Nishikawa, Y; Fujimura, H; Takeyama, H
• Feeding effect on reducing reactive oxygen species in the scleractinian coral Galaxea fascicularis2025 · <p>Reactive oxygen species (ROS) are thought to be involved in the mechanism of coral bleaching caused by high water temperature. Corals able to acquire nutriments through heterotrophy are more resilient to bleaching. However, the detailed mechanism for the alleviation of coral bleaching is not known. Here, we investigated the effects of feeding on ROS production in the coral <i>Galaxea fascicularis</i> to evaluate its potential as a mitigation technique of coral bleaching. The culture experiment was conducted with <i>G. fascicularis</i> in a 2×2 factorial design with and without food, ambient water temperature (27°C), and high water temperature (32°C). <i>Artemia salina</i> was used as a food source. The results showed that SOD enzyme activity in coral and zooxanthellae increased significantly at higher water temperatures and feeding led to a decrease of this activity. This indicates that feeding can reduce ROS production, especially in the host tissue, and potentially lessen cellular damage during heat stress. However, bleaching was not completely alleviated by feeding with reduced zooxanthellae density, chlorophyll-<i>a</i> and zooxanthellae protein contents observed under high water temperatures. Moreover the addition of food also led to lower calcification rates, regardless of temperature. These findings highlight the potential of using food addition as a mitigation technique of coral bleaching but this will require further investigation on the long term effects of feeding to better understand the limitations of the technique.</p>

• マイクロプラスチックのサンゴ礁における動態と造礁サンゴへの影響2024 · 基盤研究(C)
• サンゴの白化現象メカニズム究明と大規模白化に対する生物化学的防止・救済策の確立2018 · ■■■
• 造礁サンゴの抗酸化能向上による白化耐性の評価2015 · 基盤研究(C)
• 造礁サンゴの抗酸化能向上による白化耐性の評価2015 · ■■■

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