2018 Volume 41 Issue 4 Pages 91-96
To clarify the effects of the musty odor algae Coelosphaerium sp. on the physiological activity and uptake of musty odor adhesion components by Corbicula japonica, changes in its filtration rate and condition index and the content of geosmin and Chl.a within its soft tissue by sand exclusion in Lake Shinji in 2009 were surveyed. The abundance of Coelosphaerium sp. increased from April to May and from September to December, coinciding with the musty odor periods. The filtration rate of C. japonica decreased in spring when Coelosphaerium sp. dominated. Reduction in the condition index was observed in autumn. We suggested that dominant algae, including Coelosphaerium sp., were consumed by the clams during the musty odor period, leading to their reduced physiological activity. The musty odor of C. japonica was controlled by sand exclusion during the early stage of the musty odor period, and geosmin was not detected in the soft tissue of C. japonica. It is likely that the musty odor of C. japonica is caused by the direct uptake of Coelosphaerium sp. in the body. In contrast, the musty odor was controlled in the later period by sand exclusion and the decrease in the geosmin concentration in the soft tissue was limited. It is likely that geosmin moved into the tissues during the later period.
