Abstract
We analyzed the relationship between abundance of cyanobacteria and stability of density stratification in several eutrophic reservoirs in Japan. Under weak stratification conditions, which corresponded to N 2 = O (10-4) - O (10-3) (s-2), cyanobacteria rarely formed water bloom. In reservoirs where artificial destratification equipments were installed, N 2 and the abundance of cyanobacteria decreased. The difference of the minimum N 2 in which cyanobacteria can grow was supposed to depend on fetch. These results suggest that buoyancy frequency be an effective index for planning and operating artificial destratification systems for preventing water bloom.
