ToxSci Advance Access originally published online on May 2, 2003
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Toxicological Sciences 74, 51-65 (2003)
Copyright © 2003 by the Society of Toxicology
ENVIRONMENTAL TOXICOLOGY |
Oxidative Stress and Bioindicators of Reproductive Function in Pulp and Paper Mill Effluent Exposed White Sucker
* Department of Zoology, University of Guelph, Guelph, Ontario, Canada N1G 2W1;
National Water Research Institute, Environment Canada, Burlington, Ontario, Canada L7R 4A6;
Department of Biology, University of New Brunswick, Saint John, New Brunswick, Canada E2L 4L5;
Cam Portt and Associates, 56 Waterloo Avenue, Guelph, Ontario, Canada N1H 3H5; and
¶ Department of Plant Agriculture, University of Guelph, Guelph, Ontario, Canada N1G 2W1
This study investigates oxidative stress and bioindicators of reproductive function in wild white sucker (Catostomus commersoni) collected from environments receiving pulp and paper mill effluent discharges in northern Ontario. Samples were collected over an eight-year period adjacent to three pulp and paper mills using a variety of processing and bleaching techniques. Fish collected downstream of pulp and paper mills within the Moose River basin exhibited elevated hepatic and gonadal 2-thiobarbituric acid reactive substances (TBARS), the presence of which is indicative of oxidative stress in these tissues. Within the Jackfish Bay system, exposure to pulp and paper mill effluent did not elevate hepatic or gonadal TBARS. Hepatic cytochrome P4501A activity (CYP1A) and fatty acyl-CoA oxidase (FAO) activities were frequently increased in livers of Moose River basin fish exposed to pulp and paper mill effluent, while lower activities of both enzymes were found within fish from the Jackfish Bay system. This suggests that oxidative stress may be related to CYP1A and FAO activities. Within the Moose River system, increases in measures of oxidative stress (TBARS, FAO) were generally coincident with decreased levels of 17 ß-estradiol; however, testosterone was often lower in Jackfish Bay system fish without any commensurate changes in oxidative stress. The suite of reproductive and oxidative stress parameters measured in this study varied between seasons and mills suggesting responses to effluent are dynamic and effects are complicated by different receiving environments. The relationship between gonad size, gonadal oxidative stress, and circulating plasma steroids remains unclear.
Key Words: oxidative stress; 2-thiobarbituric acid reactive substances; fatty acyl-CoA oxidase; hepatic cytochrome P4501A; pulp and paper mill effluent; plasma steroids, fish reproduction.