1994 Fiscal Year Final Research Report Summary
Plankton ecosystem dynamics and environment in Tokyo Bay
| Project/Area Number |
04454093
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
General fisheries
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| Research Institution | Tokyo University of Fisheries |
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Principal Investigator |
MURANO Masaaki Dept.Fisheries, Tokyo Univ.Fisheries, Professor, 水産学部, 教授 (90013565)
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| Co-Investigator(Kenkyū-buntansha) |
MARUYAMA Takashi Dept.Fisheries, Tokyo Univ.Fisheries, Assis.Prof., 水産学部, 助手 (60106755)
SEGAWA Susumu Dept. Fisheries, Tokyo Univ. Fisheries, Assoc.Prof., 水産学部, 助教授 (30092589)
ISHIMARU Takashi Dept.Fisheries, Tokyo Univ.Fisheries, Assoc. Prof., 水産学部, 助教授 (90114371)
OMORI Makoto Dept.Fisheries, Tokyo Univ.Fisheries, Professor, 水産学部, 教授 (10013567)
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| Project Period (FY) |
1992 – 1994
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| Keywords | Tokyo Bay / Ecosystem / Environment / Nutrient salt / Plankton / Model |
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| Research Abstract |
We conducted monthly observations for five yesrs (1989-1993) at two stations in inner part of Tokyo Bay and for one year at 10 stations from the innermost part to the mouth of the Bay (1993) Environmental factors such as water temperature, salinity, nutrients and Chl a were measured for five years and POC and PON for one year. We tried to figure out the average feature of seasonal changes in plnakton biomass by using five-year observation data. We also analyzed the budget of nitrogen by using a box model based on the one year whole bay observation data and also made an ecosystem model of anual change in phytoplankton biomass to assess the main factors inducing the biomass fluctuation. Results are as follows ;
1. Phytoplankton blooms occur in February, July and September.
2. Concentration fo dissolved inorganic nitrogen decreased in summer but phosphate and silicate were eluted from the bottom and their concentrations increased in summer.
3. Nutrients could rarerly be a limitting factor for phytoplnkton growth in Tokyo Bay.
4. Main form of outoflowing nitrogen from Tokyo Bay to the Ocean is particulate organic form in summer and dissolved inorganic form in winter.
The main factors controlling phytoplankton biomass are solar radiation, mixing layr depth and grazing by zooplankton.
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