Studies on the succession of blue#x2010;green algae,Microcystis, Anabaena, OscillatoriaandPhormidiumin Lake Kasumigaura

摘要

This study was conducted to examine and determine the factors affecting dominance of the blue#x2010;green algal species of genusMicrocystis, Anabaena, OscillatoriaandPhormidiumfrom 1988 to 1990 in eutrophic Lake Kasumigaura. The algal dominancy of the threeAnabaenaspecies,A. affinis,A. flos#x2010;aquaeandA. spiroides, took place in early summer, while the dominance of theMicrocystisspecies,M. aeruginosa, M. viridisandM. wesenbergii, took place from summer to fall. Water samples were collected at Tsuchiura Harbour in Lake Kasumigaura. The correlations between cell numbers of blue#x2010;green algal species and water qualities were investigated. The growth rates of algaein situwere determined. Af.aeruginosashowed the highest increasing growth rate, while Af.viridiswas the lowest decay rate in theMicrocystisspecies.M. aeruginosaexhibited high single correlations between water temperature, pH, total chemical oxygen demand (T#x2010;COD) and dissolved chemical oxygen demand (D#x2010;COD). The cell numbers of blue#x2010;green algal species were also compared with each other to know any correlation. The high correlations between the threeAnabaenaspecies were observed.