Algae. 1996; 11(1): 161-169.

Diel Changes in Vertical Distributions of Microcystis in the Sonaktong Reservoir

Ae Ran Choi, Mee Jeung Park, Jin Ae Lee, Ik Kyo Chung

Department of Environmental Science, Inje University, Department of Marine Science, Pusan National University

Observation was made over 24 hour periods on August 28 - 29, 1995 to elucidate the diel changes of vertical distribution of Microcystis, which formed dense scum in the Sonaktong Reservoir, Korea. The profiles of chlorophyll a concentration provided a discernable diel vertical distributional pattern, which were mostly related to the changes of wind velocity. The increase in ambient pH was involved in the scum formation, and nutrient limitation was not important for the diel change of vertical distribution of Microcystis. There was highly significant relationship between FDC and chlorophyll a concentration of algal scum at the water surface, and high algal cell division rates were attributed to the development of algal scum. The mortality of Microcystis was assumed to be involved in weakening of the scum. The ultrastructure of Microcystis aeruginosa showed that the gas vesicles were the most prominent structure.

Keywords : diel changes, blue green algae, Microcystis, algal bloom, buoyancy, scum formation, eutrophication