| Project/Area Number |
10660177
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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 |
General fisheries
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| Research Institution | Mie University |
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Principal Investigator |
TANIMURA Atsushi Mie University, Fac.of Bioresources, Associate Professor, 生物資源学部, 助教授 (10125213)
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| Co-Investigator(Kenkyū-buntansha) |
KAWAMURA Akito Mie University, Fac.of Bioresources, Professor, 生物資源学部, 教授 (10111163)
石川 輝 三重大学, 生物資源学部, 助手 (00273350)
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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 |
¥2,800,000 (Direct Cost: ¥2,800,000)
Fiscal Year 2000: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1999: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1998: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Keywords | culture farming / natural plankton ecosystem / Ago Bay / Matoya Bay / nutrients / chlorophyll a / microbial food chain / river discharge / 英虞湾 / カイアシ類 / Olthona / Acartia / Paracalanus / クロロフィルa / 物質循環 / 種の多様性 / ピコプランクトン / ナノプランクトン |
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| Research Abstract |
The aim of the present study is to assess the possible environmental impact caused by culture farming and river discharge. Intensive data collection and observations were carried out during 1996 and 2000 to determined the variations of physical and chemical parameters and their impacts on the natural plankton ecosystem in Ago Bay and Matoya Bay, which are both typical embayments with pearl oyster and/or oyster culture grounds, respectively.
In Ago Bay, nutrients were continuously supplied from the bottom sediment during summer. The size-fractionated chlorophyll a measurements and the microscopic observations revealed that the picoplankton and nanoplankton were major components in term of carbon biomass throughout the year. The calculated potential carbon flow from pico-sized plankton including bacteria to micro-sized plankton indicate that the conduit for organic materials is driven inainly through the microbial food web, e.g. picoplankton-heterotrophic nanoflagellates-microzooplankton,
… More
througout the year. It is also suggested that the microbial food chain affect the mesozooplankton biomass.
In Matoya Bay, the phytoplankton biomass based on chlorophyll a increased in summer and autumn. NO_3-N was mainly supplied from the inflow rivers and the concentration increased in summer and autumn in the bay. PO_4-P and NO_2-N were mainly supplied through regeneration from the bottom at the interior bay, and the active regeneration of PO_4-P occurred in summer and autumn. The main source of SiO_2-Si in the bay was the inflow rivers, but it also influenced by regeneration from the bottom at the interior bay in summer and autumn. Redfield-ratio and half saturation constants were indicated that phytoplankton biomass in the bay was usually limited by nitrogen, and occasionally, by phosphorus when river flow was higher in summer and autumn. Therefore, it was suggested that loading nitrogen from the inflow rivers and active regeneration of PO_4-P from the bottom at the interior bay triggered the increase of phytoplankton biomass in summer and autumn. Less
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