Seasonal Succession of Toxic Cyanobacteria and Microcystins Concentration in Paldang Reservoir

Algae > Volume 15(1); 2000 > Article

Algae 2000;15(1): 29-35.

Hae-Kyung Park, Won-Hwa Jheong, Oh-Sang Kwon, Jae-Keun Ryu

ABSTRACT

The seasonal succession of algal growth and dominant species were investigated from 1996 to 1997 in Paldang Reservoir, which is a man-made dam lake for drinking water source. Cyanobacterial species grew dominantly during summer and autumn, and diatoms in the winter and spring. Microcystis was a dominant genus during summer time. It was revealed that water temperature was a major limiting factor to cyanobacterial production and that precipitation followed by dam gate operation also affected the abundance and dominance of cyanobacterial genera in Paldang Reservoir. The temporal variation of cyanobacterial biomass and microcystins concentration in Paldang dam site was monitored from July to December in 1997. The cyanobacterial biomass ranged to ~11,243 cells/ml and the dominant genus was Microcystis until September and changed to Aphanizomenon from October when water temperature dropped below 15degree C. The total concentrations of microcystins in lake water were 0.057~0.488μg/l. Highest concentration of microcystins in lake water was found during the exponential growth phase of Microcystis bloom. The dissolved microcystins in the lake water were detected at the end of cyanobacterial bloom, having range of 0.054~0.076μg/l.

Key words: man-made dam lake, microcystins, Microcystis, Paldang Reservoir