河床の大礫に付着したコケの剥離に関する実験的研究

抄録

The growth of aquatic mosses attached to cobbles composes bed material in riffles was confirmed in a river in Japan. Covering bed material with aquatic mosses reduces the biomass of attached algae that is a source of energy for commercial fish. This study focuses on how much and how the aquatic mosses keep their coverage on the river bed in riffles after suffering flood disturbances. Resistance to disturbances due to high-speed water flow and sediment impingement on mosses and the rolling of the cobble attached with mosses was investigated by a laboratory experiment. We observed that intermediate disturbance seems to remove silt in the biofilm but the biomass of mosses had tend to be maintained. Based on visual inspection of moss cover following the experiment, we found that the remaining moss consists of short fresh stems. The relationship between the rate of moss detachment and work due to sediment impingement has investigated and the existence of the optimal work per sediment impingement has been clarified.