Algae. 1997; 12(4): 283-290.

Distribution and Population Dynamics of Microcystis (Cyanophyta) in the Naktong River

Jae-Ki Shin, Kyung-Je Cho

Water Resources Research Institute, KOWACO, Department of Biology, Inje University

Microcystis population in the Naktong River was monitored during the algal bloom period from 1994 to 1996. Blue-green algae Microcystis began to increase form May to June and decrease from May to June and decrease from October to early November, and surface algal scum were made in August after the rainly seasons. Five Microcystis species were observed i.e., M. aeruginosa, M. viridis, M. wesenbergii, M. ichthyoblabe, and M. novacekii, M. aeruginosa population tended to predominate throughout the algal bloom periods, but its variation were irregular during the season. M. viridis, M. wesenbergii, M. ichthyoblabe and M. novacekii in the lower part of Naktong River were appeared early (May~June) stage and middle (July~August) stage of bloom, respectively. Microcystis colony size exponentially increased toward the lower part of the river and their exponential growth occur scums in surface waters. Algal-bloom of Microcystis would be correlated with environmental factors such as inorganic N·P concentration, incident solar radiation, water temperature, and summer drought in the Nakton River.

Keywords : distribution, dynamics, Microcystis population, Water-bloom