threatened species

Freshwater fish fauna was compared among 5 types of revetments: wooden revetment, block mat revetment, and other three types by Onikura et al.（2007） in irrigation canals and ditches in the Chikugo and Saga Plains. The block mat revetment had negative effect on fish species richness and appearances of several threatened species, while the wooden revetment was evaluated to have a high conservation effect on the species richness because the average number of species were almost as same as the earth revetment. However, wooden revetment was shown to be impact on only golden venus chub among the threatened species. Therefore, in the future management and reconstruction of wooden revetments, it is necessary to consider the environmental preference of this fish. From the wood consumption of the wooden revetment in irrigation canals and ditches reconstructed by Saga Prefecture since 2012, the carbon storage quantity was estimated to exceed 40,000 ton-CO^2, which was estimated to be equivalent to about 15,000 times of annual CO^2 emission per household. These results support that the canals and ditches of the wooden revetment has not only previous multifaceted function but also a biodiversity conservation and a carbon storage function.