Abstract
Anisogammarus sp. collected from a mountain stream had been kept in respective conditions of different temperature from 5℃ to 20℃ over a period of 24 hours for the acclimatization. Toxicity test of Temephos was conducted at 5,10,15℃ and 20℃. In each beaker of 200ml containing 100ml of water, individuals of adult Anisogammarus sp. were placed. Temephos which was diluted with alcohol was added to become 1,5ppm and 10ppm respectively. Exposure period to the chemical was 10,30,60 minutes and 180 minutes. After respective exposure period, animals were transferred into clean water and mortality was observed 24 hours later in the rooms of the respective conditions of temperature. Three replicates were taken for each experimental condition. Toxicity of Temephos depended on the water temperature. In the case of 1ppm, the mortality of Anisogammarus sp. changed two times or more in accordance with the change of temperature from 10℃ to 20℃. Mortality of the animals also depended on the exposure period of the chemical. The relationship between the logexposure period and the mortality was linear in general in each concentration. The slope of the regression changed according to the temperature in the case of 5ppm, whereas the regression lines converged in the case of 10ppm. It was thought from the results that Anisogammarus sp. would not be damaged in the field if the concentration of Temephos was 1ppm and the exposure period was less than one hour.
