Tolerance for Prolonged Darkness of Three Phytoplankton Species, Microcystis
aeruginosa (Cyanophyceae), Scenedesmus
quadricauda (Chlorophyceae), and Melosira
ambigua (Bacillariophyceae) |
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Authors: | Eiichi Furusato Takashi Asaeda Jagath Manatunge |
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Institution: | (1) Environmental Hydraulic Institute Ltd., 5-9-7 Negishi, Minami-ku, Saitama-shi, Saitama, 336-0024, Japan; Tel./Fax:;(2) Department of Environmental Science & Human Engineering, Saitama University, 255 Shimo-okubo, Sakura-ku, Saitama-shi, Saitama 338, Japan; E-mail: |
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Abstract: | Phytoplankton community dynamics are affected not only by atural events such as overwintering but also by artificial events such as artificial circulation and related darkness conditions. In order to clarify the effect of tolerance for prolonged darkness on community succession, laboratory cultures of three phytoplankton taxa, Microcystis aeruginosa(Cyanophyceae), Scenedesmus
quadricauda(Chlorophyceae), and Melosira
ambigua(Bacillariophyceae) were carried out in darkness. The period of darkness was varied: 5, 10, 15, 20 days, and the control. Thereafter, all samples were reilluminated. After more than 10 days of darkness, M. aeruginosa decreased markedly with the length of the darkness period and was reduced to only 1% of the initial cell number after 20 days darkness. In contrast, S. quadricauda and M. ambigua retained their biomass even after 20 days of darkness. After restarting the light–dark cycle, however, all three species similarly increased exponentially and reached their maximum biomass levels. These results suggest that differences in tolerance for prolonged darkness may cause the succession of the phytoplankton under certain conditions. |
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Keywords: | algal bloom artificial circulation community succession darkness tolerance phytoplankton |
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