STUDY ON CHANGES OF RIVER BED ENVIRONMENT AND BENTHIC ANIMALS AT THE MOUNTAINOUS RIVER IN TAMA DISTRICT

Abstract

In this study we investigated about annual changes ofbenthic animals and river bed environment on the Hirai river, the Aid-river and Kitaasa-river of the Tama district in the Tokyo. In the Hirai river and the Kitaasa-river, we examined about sediment volume among gravel and benthic animals in each microhabitats at riffles and pools, and investigated the relation between sediment and benthic animals. Results of the monitoring, it is observed that a velocity changing takes control of the river bed environment, and also a condition of existence for benthic animals. Therefore, it was considered that volume of mud is an index for river bed environment