Changes of Dominant Species of Phytoplanktons and Hydrological Causes of Water Bloom in the Lake Unmun, Cheongdo-gun, Gyeonsangbuk-do

doi:2007.22.4.261

Algae > Volume 22(4); 2007 > Article

Algae 2007;22(4): 261-271. doi: https://doi.org/10.4490/algae.2007.22.4.261

Mi-Kyung Kim¹^*, Soon-Hwa Lee² and Chul-Hwee Lee²

¹Marine Science Research Center, Environmental Research Institute
²Architecture and Environmental Engineering, Yeungnam University, Gyongsan 712-749, Korea

ABSTRACT

The variations of species compositions, standing crops and seasonal succession of phytoplanktons including Cyanophyceae, Chlorophyceae and Bacillariophyceae were investigated with physico-chemical elements of water to clarify the causes of water bloom according to the water depth in the Lake Unmun. The increased amounts of turbidity, T-N, T-P and SS originated from heavy rain and typhoon in the middle of June provoked to produce phytoplanktons. In July and August, the dominant species was Peridinium sp., while the subdominant species was Microcystis aeruginosa. In October, Aulacoseira distans was dominant and Asterionella formosa was subdominant. During the period of water shortage, the concentrated pollutants caused the decrease of precipitation, the long stagnation time of water body and the mixed pollutants by upwelling as decreasing water temperature could accelerate the water bloom. The preventives to decrease microalgal generation should be controled by the stagnation time of water body by increasing outflow to intercept water bloom such as Aulacoseira sp. in October as well as summer.

Key words: dominant species, Lake Unmun, phytoplankton, seasonal variation, water bloom