2005 Volume 58 Issue 3 Pages 34-43
To evaluate the impact of sediment flushing on fish, we need to predict the physiological impact of turbid water. For some indices used to evaluate the impact, the concentrations of suspended solids and dissolved oxygen are very im-portant. In this study, we clarified the mechanism of the physiological impact of turbid water on fish and constructed a model that calculates the rates of mortality, or asphyxiation, based on the concentrations of suspended solids and dissolved oxygen.
First, we examined the temporal variation in the concentrations of suspended solids and dissolved oxygen at three sites subject to sediment flushing. Then, we conducted two tank experiments. The first investigated the relationship between the concentration of suspended solids and the mortality rate of char with sufficient dissolved oxygen, and the second examined the physiological impact of an increase in the concentration of suspended solids. Third, we modeled the results of the tank experiments. We postulated that as the concentration of suspended solids increases, the volume of oxygen absorbed decreases as the gills become covered with sediment. Finally, we examined the physiological impact of sediment flushes at the three sites using the model.
The tank experiments showed that an increase in the concentration of suspended solids and a decrease in the concentration of dissolved oxygen both lead to asphyxia. Given the temporal variation in the concentrations of suspended solids and dissolved oxygen, the model has the potential to roughly estimate the rates of mortality or asphyxiation of fish.
