Abstract
The Matsuura river, study site of present study, has three Unionoida species which are known as good indicator of river environment health. However Anodonta lauta, one of the three species, has been drastically decreasing in past decades. One of those reasons is change of flood water disturbance system against their habitats. Though this phenomenon is strongly related to hydraulic flow of the habitat and hydraulic characteristics of Unionoida mussels, relationship between hydraulic flow and hydraulic characteristics of Unionoida mussels are not known yet. If we can reveal that, conservation and restoration skills for river environment should be improved. In this study, we focus on hydraulic characteristics of three Unionoida species, and conducted a hydraulic experiment. As a result, Anodonta lauta had characteristic which was susceptible to the hydraulic flow. In addition, smaller sized mussels were settled slowly and easily influenced by flowing water.
