Studies on the succession of blue‐green algae,<i>Microcystis, Anabaena, Oscillatoria</i>and<i>Phormidium</i>in Lake Kasumigaura

Abstract

Abstract This study was conducted to examine and determine the factors affecting dominance of the blue‐green algal species of genus Microcystis, Anabaena, Oscillatoria and Phormidium from 1988 to 1990 in eutrophic Lake Kasumigaura. The algal dominancy of the three Anabaena species, A. affinis,A. flos‐aquae and A. spiroides, took place in early summer, while the dominance of the Microcystis species, M. aeruginosa, M. viridis and M. wesenbergii, took place from summer to fall. Water samples were collected at Tsuchiura Harbour in Lake Kasumigaura. The correlations between cell numbers of blue‐green algal species and water qualities were investigated. The growth rates of algae in situ were determined. Af. aeruginosa showed the highest increasing growth rate, while Af. viridis was the lowest decay rate in the Microcystis species. M. aeruginosa exhibited high single correlations between water temperature, pH, total chemical oxygen demand (T‐COD) and dissolved chemical oxygen demand (D‐COD). The cell numbers of blue‐green algal species were also compared with each other to know any correlation. The high correlations between the three Anabaena species were observed. Keywords: Microcystis Anabaena Oscillatoria Phormidium succession