2019 Fiscal Year Research-status Report
Identifying "super corals" in Mauritius: what physiological factors promote high recovery after bleaching?
| Project/Area Number |
18KK0298
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| Research Institution | Shizuoka University |
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Principal Investigator |
CASARETO Beatriz 静岡大学, 創造科学技術大学院, 特任教授 (60402244)
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| Co-Investigator(Kenkyū-buntansha) |
藤原 健智 静岡大学, 創造科学技術大学院, 教授 (80209121)
天野 豊己 静岡大学, 理学部, 准教授 (90297945)
RAMPHUL CHITRA 静岡大学, 創造科学技術大学院, 研究員 (20832661)
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| Project Period (FY) |
2018-10-09 – 2021-03-31
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| Keywords | Mauritius / super coral / Coral bleaching / oxidative stress / thermal tolerant / genome analysis / Symbiodiniaceae / physiological factors |
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| Outline of Annual Research Achievements |
This study aims to describe the physiological mechanisms that promote a successful response of thermally tolerant corals, which we define as “super corals". We surveyed two target reefs: Albion (A) (shallow, human impacted) and Belle-Mare (BM) (deep, less affected). Physico-chemical and biological characters were already described in 2018 year report. We sampled 17 and 19 coral colonies in A and BM respectively. Results from these studies are: similar photosynthetic activity (Fv/Fm) 0.54 in A and 0.56 in BM; similar Chl-a concentration (microgr/cm2) as 12.4 in A and 11.9 in BM; high Chl-a allomer/Chl-a as 14 in BM vs. 7 in A; low zooxanthellae density (cells/cm2) as 770,000 in BM vs. 990,000 in A, but high Chl-a per zooxanthellae (pg/cell) as 32 in BM vs. 14 in A; high glycerol concentration (microg/mg protein) as 13.5 in BM vs. 3.6 in A; high glycerol/glucose as 0.7 in BM vs. 0.2 in A. From the present data, rather than in A, corals in BM were highly exposed to stressful condition: high Chl-a allomer/Chl-a indicated oxidative stress condition and holobiont affected judging from the high gly/glu ratio in BM corals. Nevertheless these corals were successful in keeping high Fv/Fm with healthy zooxanthellae (even under bleached condition) with high Chl-a/cell. High % of the bacterium Endozoicomonas in Pocillopora corals at BM confirmed their healthy condition. The presence of Symbiodiniaceae of Clade D (Genus Durusdinium) (thermal resistant) reinforced “super coral” features. In terms of coral species, Pocillopora eydouxi, Pavona sp and Montipora sp were the successful.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
We had successfully surveyed two targeted reefs and had identified the main environmental stressors. We had performed detailed physiological studies to identify the parameters to be applied in the evaluation of “super corals”. On these bases, we had identified “super corals” species. We had also accomplished training and education of young scientists: two recent post-doc. and 5 graduated students joint the research team during field survey in Mauritius and posterior samples treatment and data analysis. We had submitted an application for UNESCO/K. Obuchi Young Researcher Fellowship to give training to a Mauritius PhD candidate at Shizuoka University from August to October 2020. We had prepared a joint report to fulfill the requirements for an RCA between Univ. of Mauritius and Shizuoka Univ. that also covers the requested report for coral sampling permits. We had published one joint paper with Mauritius scientists (Journal of Sustainability Science and Management, accepted April 2020) and we submitted two join manuscripts to Journal of Marine Pollution (Springer) and Journal of Ocean Science (Springer). We had also submitted two joint abstract to the 14th International coral Reef Symposium (ICRS) to be held in Bremen, Germany from 5-11 July 2020, but postponed to 18-28 July 2021 due to the COVID-19 pandemic. Moreover, due to the COVID-19 we were not able to trip to Mauritius planned from 11-19 March 2020, therefore we could not develop the planned surveys and incubation experiments and the 2 days joint workshop planned to be held during the same period.
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| Strategy for Future Research Activity |
2020-2021 fiscal year: physiological responses of corals under normal vs. elevated seawater temperature and light.
(a) Continuing surveys in the two selected reefs. (b) Evaluation of coral physiological responses using incubation experiments under normal vs. stressful conditions of temperature and light with (3-4 days), and posterior recovery (4-6 days). Coral nubbins under normal (ambient) and stressful temperatures (plus 2 to 4 °C) and light (over 1500 micromol cm-2 sec-1) will be incubated to evaluate their responses in the reduction of oxidative stress and apoptosis, defense against infections, feeding under normal or bleached conditions. We will test posterior recovery capacity, by placing the corals back to ambient conditions. Experiments will be done at the University of Mauritius (UoM) laboratory facilities. (c) Similar incubations will be performed to measure coral grazing rates on plankton collected in the same reefs. (d) We will hold the second workshop at UoM.
Summary, conclusions, recommendations:
(a) Create a first molecular genetic catalogue/database for Symbiodinium from corals of Mauritius. (b) Summary of data with characterization of a “super coral” and identification of such areas in Mauritius that can provide “super corals” for the future of African Reefs (c) Make relevant recommendations for inclusion of areas bearing “super corals” in Marine Protected Areas
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| Causes of Carryover |
2019年度のモーリシャス大学との共同研究及びワークショップ（モーリシャス水産・漁業省・在モーリシャス大使館等も参加）は2020年2月23日から3月6日まで行う予定で、研究代表者の計画に従い準備を行い、飛行機・ホテル等予約が完了していた。しかし、この時期COVID-19によりモーリシャスで感染者が拡大したため、在モーリシャス大使館およびモーリシャス大学と協議して調査研究の延期を決めた。そのため、飛行機のキャンセル料を支払い、残りの大部分の旅費が次年度の繰り越しとなった。この旅費は2020年10月に予定している調査研究に調査費用として使用する。
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Research Products
(13 results)
