Effects of multiple effluents on resident fish from Junction Creek, Sudbury, Ontario.

Junction Creek in Sudbury, Ontario, Canada receives effluent from three metal mining effluents (MMEs), as well as urban run-off and municipal sewage treatment plant (STP) discharges. The present study examined organismal and sub-organismal end-points in prespawning fathead minnow (FHM; Pimephales promelas) and creek chub (CC; Semotilus atromaculatus) collected in May 2004 from Junction Creek. Metal body burdens of Cd, Cu, Rb, Se, and Sr increased in a gradient down Junction Creek in both species. In general, male fish had lower body weights downstream of effluents, while females were unchanged or larger compared to reference fish. Livers were larger in FHM of both sexes downstream of STP and in CC downstream of two MMEs compared to reference fish, while gonad weight was unchanged. The most consistent finding was delayed development, increased cell death and increased eosinophilia in FHM testes collected downstream of all effluents, while female FHM and both sexes of CC gonads were relatively unaffected. In conclusion, the results of the current study in Junction Creek suggest that male FHM reproduction may be sensitive to multiple effluents, but failed to clearly establish whether MME or STP effluents were causative agents over urban inputs or historical contamination.

Oxidative stress and bioindicators of reproductive function in pulp and paper mill effluent exposed white sucker.

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 beta-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.