BROWN TROUT EXPOSED TO ACID-TREATED AND NONTREATED HUMIC WATER FROM LAKE SKJERVATJERN

Lake Skjervatjern was divided into two separate basins. One basin and its catchment were treated with sulphuric acid and ammonium nitrate. T he other part was kept as a control. Brown trout was exposed to acid-t reated and nontreated water from the outlets of the two basins. The re sults showed higher mortality in acid-treated water compared to nontre ated water from Lake Skjervatjern. Chloride concentration in blood pla sma was lower in fish exposed to acid-treated water, indicating a high er degree of stress. Some physical/chemical parameters showed differen t values for the acid-treated basin compared to water from the nontrea ted one, e.g., increasing concentrations of sulphur and nitrogen were seen in the acid-treated basin. However, no physical/chemical paramete r or group of parameters has been identified from the two basins that cari explain the difference in fish mortality and stress.