Distributions and Seasonal Variation of <i><b>Microcystis</b></i> rDNA in Sediment of Lake Kasumigaura

Abstract

Cyanobacterial blooms, consisting mainly of Microcystis spp., occur during summer in Lake Kasumigaura, Japan. Some previous studies have suggested that these blooms are enhanced by the recruitment of overwintering cells from the lake sediment. However, the volume and distribution of Microcystis in the sediment of Lake Kasumigaura are unknown. The purpose of this research was to clarify the volume, distribution, and seasonal variation of Microcystis in Lake Kasumigaura using real-time polymerase chain reaction PCR . The results showed that cell densities differed among stations and seasons. Moreover, it was suggested that cell recruitment occurred in early June in Tsuchiura Bay. Additionally, the lake bottom sediment is an unsuitable environment for the accumulation of Microcystis cells because the cells decomposed immediately and/or were transported by disconcertion at the surface of the sediment in Lake Kasumigaura.