| Project/Area Number |
17570016
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Ecology/Environment
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| Research Institution | Yokohama National University |
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Principal Investigator |
AMEMIYA Takashi YNU, Graduate School of Environment and Information Sciences, Associate Professor, 大学院・環境情報研究院, 助教授 (60344149)
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| Co-Investigator(Kenkyū-buntansha) |
ITOH Kiminori YNU, Graduate School of Environment and Information Sciences, Professor, 大学院・環境情報研究院, 教授 (40114376)
MATSUDA Hiroyuki YNU, Graduate School of Environment and Information Sciences, Professor, 大学院・環境情報研究院, 教授 (70190478)
INAMORI Yuhei NIES, Bio-Eco Engineering Lab., Executive Researcher, バイオエコ研究室, 室長 (10142093)
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| Project Period (FY) |
2005 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2006: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2005: ¥2,900,000 (Direct Cost: ¥2,900,000)
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| Keywords | Lake / Eutrophication / Stability / Conservation Ecology / Restoration of Environment / Resilience / Biomanipulation / Regime Shift / 物質循環 |
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| Research Abstract |
Population dynamics and stability in a model lake ecosystem have been studied by using a microcosm consisting of algae (M.aeruginosa), flagellate (M.guttula), and few bacteria (P.putida, and so on). The predatory effect of M.guttula on M.aeruginosa exhibited a trade-off with respect to the concentration of nutrient; The quality of food (M.aeruginosa) was increased with increasing the nutrient concentration, thus the growth rate of M.guttula was increased. However, high nutrient conditions increased the photosynthetic activity of M.aeruginosa, which increased the pH of the solution, and thus the growth rate of M.guttula was decreased. Under the conditions of intermediate nutrient conditions, M.aeruginosa was extinct or survived depending on the initial population of M.guttula, suggesting bistability in the model system.
A micro-Fourier transform infrared (FTIR) spectroscopy was used to study changes in cell compositions of bio-molecules in M.aeruginosa depending on the nutrient concentrations. The amounts of glycogen and lipid have been found to increase in the logarithmic growing phase under the high nutrient conditions. This may suggest that M.aeruginosa absorbs and uses nutrients effectively under eutrophicated conditions.
A new mathematical model of a lake ecosystem has been constructed taking into account of increase in water temperature. Analyses of the model shows that there exists a critical value of water temperature, and that algal bloom occurs if water temperature exceeds the value in summer time, suggesting regime shift in lake ecosystems. It was also pointed out that macrophytes have significant effects on suppressing algal blooms, and that management of lake ecosystems needs feed back control by taking into account of uncertainty of lake ecosystems.
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