1995 Fiscal Year Final Research Report Summary

Research on Accumulation Mechanism of Freshwater Red Tide in a Dam Reservoir

Research Project

Project/Area Number	06680491
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	Environmental dynamic analysis
Research Institution	KYOTO UNIVERSITY
Principal Investigator	SOMIYA Isao Kyoto University, Faculity of Engineering, Professor, 工学部, 教授 (60025947)
Co-Investigator(Kenkyū-buntansha)	ONO Yoshirou Kyoto University, Faculity of Engineering, Instructor, 工学部, 講師 (50152541) TSUNO Hiroshi Kyoto University, Faculity of Engineering, Co-Professor, 工学部, 助教授 (40026315)
Project Period (FY)	1994 – 1995
Keywords	fresh water red tide / Peridinium / dam reservoir / accumulation mechanism / head of lake / phototaxis / flow
Research Abstract	I.The diurnal change of distribution patterns and standing crop of Peridinium were observed at the head of Shourenji Dam Reservoir in autumn. There were three distribution patterns ; (a) accumulating at the surface in the day time ; (b) dispersing to lower layr and stream in the night ; (c) dispersing lower layr near the plunging point. The standing crop of Peridinium increased at similar rate of growth day by day. Since organisms were transported by the counter flow, The biomass periodically varied at 24 hours cycle in a day. These results show that the red tide develops and dissipates in the balance of growth, import and export. II.Swimming velocity vectors of Peridinium were measured under various temperature and light intensity conditions. Analyzing obtained data sets, we constructed a mathematical model that predicted the vertical swimming velocity of Peridinium community. Furthermore, using the water tank and the mathematical model that assuming the head of a water reservoir, we examined the accumulation and dispersion processes of red tide. The mathematical model including the vertical swimming responses could simulate the diurnal change of biomass. III.We developed the mathematical model that simulate the accumulation mechanism of freshwater red tide. It predicts the import and export using the fluid dynamics model, the vertical distribution using the vertical swimming model, and the growth using the ecological model. This model successfully simulated the temporal and spatial distribution of Peridinium at the head of Shourenji Dam Reservoir. These results suggested that accumulation mechanism of freshwater red tide could be treat in the term of engineering.