Abstract
Geology is one of the crucial components for defining riverbed materials and textures especially in mountainous streams, which might effects on their aquatic communities. In this study, the Kushida River basin, central Japan, composed of different geologic units such as plutonic, metamorphic, and sedimentary terrains, was selected to clarify the relationships between riverbed textures and benthic macroinvertebrates. We conducted field surveys at riffle and pool units in each of the 18 stations (three sites each for six tributaries) by taking into account their watershed geologies and landuses. Sediment samplings, topographic measurements and water quality monitoring (temperature, pH and electric conductivity) were undertaken at these sites. The individuals of macroinvertebrate were picked out from each of the sediment samples and identified at the species level with six “life types”, whereas their residual samples were used to analyze the riverbed textures. The topographic, geologic and ecological differences among each of locations in the tributaries have been discussed with the one / two way ANOVA tests. According to the results, it could be understood that there are strong relationships among the watershed geologies, the physical characteristics of riverbed textures and the features of species and life type compositions of benthic macroinvertebrates.
