Le poulamon atlantique (Microgadus tomcod) de l'estuaire de la riviere Miramichi et la truite arc-en-ciel ( Oncorhynchus mykiss): L'effet des usines de transformation de bois de la Miramichi et l'induction du systeme enzymatique cytochrome p4501A1 (French and English text).

摘要

This thesis attempts to determine the existence of sublethal effects in fish exposed to bleach and groundwood mill effluents. A series of three experiments were conducted in an effort to demonstrate the existence of these sublethal effects. The first experiment examined the induction of CYP1A1 mRNA in rainbow trout (Oncorhynchus mykiss) exposed in the laboratory to effluents collected from a bleached kraft mill located at Newcastle, New Brunswick. This experiment and two others carried out with the Atlantic tomcod (Microgadus tomcod); one in laboratory and one in the field, indicated that the bleached kraft mill effluent from Newcastle and the groundwood mill effluent from Nelson, New Brunswick contained products that resulted in CYP1A1 induction in Atlantic tomcod some of the time. The variations in the induction response of the CYP1A1 gene in tomcod may be related to: (1) a temporary absence of inducers, (2) a change in receptivity of tomcod due to other chemicals present in the effluent or (3) the existence of physical factors endogenous to the tomcod. However, the scope of the thesis did not permit the exploration of these possibilities. In the final experiment, caged tomcod were exposed to the pulp mill effluent in the field. Although CYP1A1 mRNA induction was observed, a similar response was found at the control site, which negates the possibility of concluding with certainty that pulp mill effluents were a source of inducers.