| Project/Area Number |
10558094
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| Research Category |
Grant-in-Aid for Scientific Research (B).
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
環境保全
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| Research Institution | The University of Tokushima |
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Principal Investigator |
MURAKAMI Hitoshi Graduate School of Engineering, The University of Tokushima, Professor, 大学院・工学研究科, 教授 (50027257)
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| Co-Investigator(Kenkyū-buntansha) |
KURATA Kengo Graduate School of Engineering, The University of Tokushima, Research Associate, 大学院・工学研究科, 助手 (40325246)
KOZUKI Yasunori Graduate School of Engineering, The University of Tokushima, Associate Professor, 大学院・工学研究科, 助教授 (60225373)
MIZUGUCHI Hiroyuki Dept.of Civil Engineering, The University of Tokushima, Professor, 工学部, 教授 (00035651)
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| Project Period (FY) |
1998 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥13,500,000 (Direct Cost: ¥13,500,000)
Fiscal Year 2000: ¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1999: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1998: ¥9,600,000 (Direct Cost: ¥9,600,000)
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| Keywords | Eutrophication / Sea Cucumber / Mytillus edullis / Ecosystem Engineering / Asteroidea / Circulation Function of Organic Matter / Restoration Technique for Ecosystem / Hypoxia / 底泥 / ナマコ / ポーラスコンクリート / 栄養塩 / 難分解性有機物 / 海水 / 硫化物 / 有効細菌 / ゴカイ / チッソ / リン / 浄化 |
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| Research Abstract |
Deterioration of bottom sediment and eutrophication of water quality have proceeded in inner bay and harbor. A vertical construction of breakwater which prevails in an enclosed sea area had reduced the complexity of habitats for marine organisms, causing unbalance of material cycle function between pelagic and bottom ecosystems. We aimed to devise a new type of breakwater that would provide a space for benthic organisms and facilitation of material cycle in an aquatic ecosystem. We also focussed on sediment reworking by feeding behavior of a common sea cucumber Stichopus japonicus inhabiting the bottom.
A preliminary steel plant was set in the front of the breakwater at the Okinosu harbor located in Tokushima city in December 1999. We conducted several investigations to elucidate the characteristics of the plant including community structures and environmental conditions. Field experiments using sea cucumbers were also carried out at the two sites, Komatsushima port and the lagoon of Rinku Park in Osaka Prefecture.
A common mussel Mytilus galloprovincialis dominated at both the plant and the vertical wall of breakwater. Dissolved oxygen concentration at the bottom was decreased below 2 mg/1 inside the plant whereas that outside the plant was remained 4 mg/1 in August. The amount of deposited seston was greater outside the plant than inside it. Relatively low concentrations of dissolved oxygen were resulted from the excessive biomass of mussels on the wall structure of the plant. We need to improve structure of the plant in order to provide habitats for benthic organisms such as sea cucumbers.
The characteristics of sediment were different due to the presence of a sea cucumber in both experimental sites. The fact that AVS contents were decreased in the presence of sea cucumbers suggested that S.japonicus had an important role in sediment reworking in a closed aquatic environment.
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