Sublethal effects of simulated pulp mill effluents on the respiration and energy metabolism of rainbow trout (Salmo gairdneri).

Rainbow trout were exposed to 0.08 X 96-hr LC50 concentration of simulated unbleached (KME-Sa) and bleached (KME-Sa + CP) kraft pulp mill effluents. A sulfate soap preparation (Sa) with and without added chlorophenols (CP) was used as the toxicant mixture. The lipid content of white muscle increased in both test groups, and its protein content decreased in the KME-Sa-treated group. The ammonia excretion rate also decreased in both test groups. These results show that there was a shift from protein to lipid metabolism. On the other hand, apart from a slight hypoglycemia, only minor changes were observed in the carbohydrate metabolism. The overall effects on blood respiratory properties were functionally insignificant. However, the effects of kraft mill effluent with and without chlorophenols were qualitatively dissimilar in several respects.