Pocillopora damicornis. サンゴの共生藻の温度・光への生理学的ストレス強化に繋がる高硝酸濃度の影響

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概要

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• Increase in sea surface temperature and excessive input of nutrient in reef waters, due to anthropogenic activities have been among the various factors responsible for bleaching and mortality of corals around the world. So, this study investigated the effects of elevated nitrate (NO3) concentration and temperature on the coral, Pocillopora damicornis. Coral fragments were incubated for two days at different temperatures (27°C and 32°C) and NO3 concentrations (∼0.4 μM and 10 μM). Following 48 hours of stress under 32°C and 10 μM NO3, the nubbins were moved to 27°C and ambient (∼0.4 μM) NO3 levels for 48 hours of recovery period. Maximum quantum yield (Fv /Fm) and maximum excitation pressure (Qm) at photosystem II indicated that combined effect of high temperature and high NO3 were more severe and only corals under these conditions exhibited an incomplete recovery. Furthermore, zooxanthellae density and pigment data showed that the response mechanism of these coral nubbins were different from high temperature or high NO3 stress only. Aftre the recovery phase, zooxanthellae density was higher (∼1.5 fold) whereas chlorophyll a per cell was lower (∼1.5 fold) than the control (27°C and ∼0.4 μM NO3) for combined stress of high nitrate and temperature. On the other hand, xanthophyll ratio for these nubbins was still significantly higher than the control, thus showing a possible mechanism of recovery by dissipating excess loght energy as heat. Hence, this study showed that under thermal stress, high nitrate amplifies damage to the in hospite zooxanthellae of the coral Pocillopora damicornis and recovery of the holobiont is more diffi cult after the stress.

著者

• 鈴木 款

  Graduate School Of Science And Engineering Shizuoka University

• 樋口 富彦

  Graduate School of Science and Technology, Shizuoka University

• ベアトリス・エステラ ・カサレト

  Graduate School of Science and Technology, Shizuoka University

• プラモド・クマル ・チュムン

  Graduate School of Science and Technology, Shizuoka University

• 入川 暁之

  Graduate School of Science and Technology, Shizuoka University

• ランジェッツト ・バグリー

  Department of BioSciences, Faculty of Science, University of Mauritius

• 石川 義郎

  Institute of Environmental Sciences

関連論文

• サンゴ内窒素配分におよぼす高温ストレスと硝酸塩の影響
• 深層水による低次生物量の増殖技術の開発
• Pocillopora damicornis. サンゴの共生藻の温度・光への生理学的ストレス強化に繋がる高硝酸濃度の影響
• 沖縄備瀬のサンゴと海草の共存海域における溶存有機炭素と微生物の役割

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