Abstract
The vertical migration of blue-green algae in a stratified dam reservoir was investigated from 12:00 Sept. 18 to 14:00 Sept. 19, 2009 (at 2 h intervals). The result shows that the rates of sinking to depths of 5 m and 9.5 m from the surface were 0.35 m·h-1 and 0.73 m·h-1, the rates of flotation toward the surface from depths of 5 m and 9.5 m were 0.41 m·h-1 and 0.79 m·h-1. A diurnal thermocline was formed. The diurnal vertical migration cycle shows that the blue-green algae floated and covered the surface at 12:00, started sinking at 14:00, and reached the deepest part (9.5 m) at 0:00. The blue-green algae flotation toward the surface from depths of 5 m and 9.5 m was observed after 2:00 and the blue-green algae reached the surface at 12:00.
