The Role of Mixing in the Mechanisms of Water Bloom by Microcystis spp.

概要

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Studies on the role of water mixing in the mechanisms of water bloom by Microcystis spp., which were composed from the three species, M. aeruginosa, M. viridis and M. wesenbergii, were conducted during the summer of 1983. Microcystis spp. are a species of blue-green algae that appears regularly in the summer in Lake Suwa, Japan. Centrifugation was used in order to separate Microcystis spp. from other phytoplankton. Thus, the floating part of the centrifugal tube was occupied by Microcystis spp. only, and the settling part was by other phytoplankton. It was clear from the experimental results of the present study that the Microcystis cells in the floating part were active in photosynthesis, while the cells in the settling part were less so. The results of the water mixing experiments showed that water mixing had a positive effect on the photosynthesis and on the growth of this algal population compared to non-mixing. At a mixing speed of 2.2 cm/sec, it was known to be an optimum condition for photosynthesis. The light saturation points changed by the mixing speeds, and were in the range of 10 to 20 Klux. It was concluded that the photosynthesis of the algal population was not inhibited under strong light in the summer season by forming the unique productive structure concentrated the algal colonies in the surface layer. However, a single colony was inhibited by a strong light of more than 20 Klux.
信州大学理学部の論文
1985-10-31