The influence of wind on the horizontal distribution of bloom-forming cyanobacteria in Akanoi Bay, Lake Biwa

Abstract

In the summer of 1995, bloom-forming cyanobacteria were observed on the surface of Akanoi Bay in the South Basin of Lake Biwa. During that summer season, the horizontal distribution of chlorophyll a concentration was measured, and the cell density of phytoplankton was counted microscopically. Two different horizontal distributions of the dominant bloom-forming cyanobacteria were observed under moderate wind conditions. The colonial cyanobacteria with aggregated filaments, Anabaena affinis, and mucilaginous clumps of Microcystis aeruginosa tended to be transported horizontally by wind, while Planktothrix agardhii with solitary filaments did not. This suggests that different cyanobacteria species may be affected by wind in different ways due to their varying physiology or morphology.