西九州沿岸に分布する有害渦鞭毛藻Cochlodinium polykrikoides Margalefの増殖に及ぼす水温，塩分および光強度の影響

概要

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An unarmored dinoflagellate Cochlodinium polykrikoides is one of the most harmful red tide organisms causing mass mortality of cultured fish in western Japanese and southern Korean coastal waters. The growth response of C. polykrikoides was examined on four strains in 54 different combinations of temperature (10-30°C) and salinity(16-36) under an illumination of 80 μmol m-2 S-1 with a photoperiod of 14 h light and 10 h dark cycle. C. polykrikoides grew well at a temperature range of 15-30°C, and a salinity range of 16-36. The highest growth rate was obtained with the combination of 27.5°C and 28-32 with maximum growth rates (μm) of 0.57-0.61 day-1. The effect of light intensity on the growth of C. polykrikoides was studied at seven levels ranging from 10 to 140 μmol m-2 S-1 with 14 h: 10 h light: dark photo cycle at 25°C. C. polykrikoides grew well at an irradiance of 20 μmol m-2 s-1 or more, but the growth was saturated at 120 μmol m-2 S-1. The half-saturation constant for growth of light intensity (Ks),μm and the threshold value (10) were 29.2μmol m-2 s-1, 0.54 day-1 and 4.5μmol m-2s-1, respectively. These results explain the tendency that C. polykrikoides forms red tides during warm seasons in high salinity water.
日本プランクトン学会,Plankton Society of Japanの論文