Hii River basin located in the eastern part of Shimane Prefecture is characterized by the river running through granitic rock areas, the basin having the brackish lakes (Lake Shinji and Lake Nakaumi) and the deep relations with the human being life from ancient times.
　Using Hii River basin, the present authors has researched the ideal way of environmental education from the view point of earthsystem and from the nurture of environmenntal literacy that is suitable for the global ages.
　The results of this study are as follows.
　We researched on the matter of cycle over Corbicula japonica that is the dominant species of the benthos in Lake Shinji. And we observed the feeding, digestion and egestion of Corbicula japonica , and classified the excretary matters. These are composed of pseudo-feces, digested feces and undigested feces. And, Corbicula japonica is not only suspension feeder but also detritus feeder.