Sublethal Effects of Chlorinated Phenols and Resin Acids on Rainbow Trout (Salmo gairdneri)

The aim of this work was to study the effects of toxic compounds in pulp and paper mill effluents on fish and fish physiology. This was done by studying the accumulation of 2,4-dichlorophenol, 2,4,6-trichlorophenol and dehydroabietic acid in fish and the physiological responses of fish to this accumulation. Tests were performed at two concentrations, 5 µg/l and 50 µg/l, and during the exposure period mainly hematological parameters were measured in the fish. The toxicants tested affected most of the parameters analysed (blood hematocrit, leucocrit, hemoglobin, mean cellular hemoglobin count; plasma glucose, lactate; liver glycogen). Significant changes were also found in enzyme concentrations of UDP-glucuronyl transferase activity in the liver. Chlorinated phenols seem to increase the activity of this enzyme while the resin acids seem to decrease the activity. The accumulation of the toxicants tested is most significant at the beginning of the exposure period and the toxicants are concentrated in the liver. After 20 days of exposure the concentrations in the liver decrease and this shows the ability of fish to eliminate the substances tested or to change them to an excretable form. The accumulation of the toxicants seems to correlate with the physiological responses of the fish.