Alterations in biochemistry and morphology of feral fish downstream from an untreated groundwood/sulphite pulp mill discharge and characterization of the effluent induced mixed-function oxygenase response
Bezte, Candi Lynne
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White suckers captured downstream from the Pine Falls pulp and paper mill exhibited an increase in liver somatic index and an induction of the mixed-function oxygenase (MFO) system and decreases in plasma testosterone, fecundity and hepatic stores of vitamins A and E. The MFOs were positively correlated with liver somatic index and negatively correlated with hepatic vitamins, condition factor and most reproductive indices; hepatic vitamins were positively correlated with condition factor and reproductive indices. The majority of the differences between reference and downstream fish appears to be related to the presence of the pulp mill, because effects diminished with increasing distance from the effluent outfall. These effects may be caused by the current (1993-1994) release of effluent and/or to the habitat degradation of the area. In a dose-response experiment the MFO enzyme system of rainbow trout was induced by an effluent concentration of 0.23%; less than one tenth of the estimated 96-hour LC50 value of 3.0%. The time-dependence of the MFO response was examined at an effluent concentration of 1% and was significantly induced after 2 days, remained at this induced level for the remaining 6 days of effluent exposure and declined within 2 days after the fish were moved to clean water. Fish downstream from the Pine Falls pulp mill exhibited responses similar to fish captured downstream from bleaching kraft pulp mills. The MFO inducer(s) in this effluent behaved like polycyclic aromatic hydrocarbons, not highly chlorinated dioxins and/or furans. At the time of this study the effluent released from the mill was untreated; a secondary treatment facility which may alleviate some if not all of these impacts has since been installed.