Consideration Focusing on the Dormant Cells of the Musty Odor-producing Cyanobacteria that Occurred in the Susobana Dam Lake

Abstract

A musty odor-producing blue-green algae, Anabaena (Dolicospermum ), outbreaks at Susobana Dam Lake in Nagano City, and a musty odor was produced at the tap water source. We investigated the cause of the outbreak, focusing on dormant cells of the genus Anabaena . Dormant cell germination experiments from the bottom mud of the dam were conducted, and field data were analyzed for the water temperature and the vertical distribution of the number of Anabaena colonies. As a result, it was suggested possibility that the dredging performed the year before the outbreak of blue-green algae accumulated dormant cells on the surface layer of the sediment and germinated as the water temperature rose, and the blue-green algae of the genus Anabaena may have occurred. At the same time, we will report a case study of sudden musty odor damage in an environment with limited equipment and personnel.