Seasonal variations of Microcystis populations in sediments of Lake Biwa, Japan

摘要: Seasonal variations of colony numbers Microcystis aeruginosa(Kutz.) Kutz. and M. wesenbergii(Komarek) Komarek in N. V. Kondrat. sediments Lake Biwa were investigated over a period 1 year. At two stations located the shallow South Basin (ca. 4 m water depth), number Microcystisfluctuated seasonally. The had tendency to gradually decrease from winter early summer, while it increased through mid-summer autumn. Since Microcystispopulation sediment was rather small, intensive growth accumulation column should be important for formation Microcystisblooms Biwa. Microcystiscolonies samples after June observed floating counting chamber under microscope. observation suggests that recruitment colonies into mostly occurs summer. deep North (70 – 90 depth) larger than Basin. Because seasonal variation not Basin, Microcystiscells do have gas vesicles, these will return column. isolated able grow cultured conditions, same way as those Therefore, may survive long time stable conditions low temperature 8 °C) darkness, accumulating each