Although multiple reproductive tests have been developed in small-bodied fish to determine the ef... more Although multiple reproductive tests have been developed in small-bodied fish to determine the effects of endocrine- disrupting substances, few direct comparisons have been made among the available tests. Side-by-side reproductive tests with mummichog (Fundulus heteroclitus) and fathead minnow (FHM; Pimephales promelas) were conducted with 0, 3, 10, and 30% effluent from a bleached kraft pulp mill in Saint John, New Brunswick, Canada. Egg production was significantly increased in mummichog exposed to 3% combined mill effluent, but no difference was observed in FHM. No differences were found in whole-body testosterone or estradiol levels in mummichog, and whole-body 11-ketotestosterone levels in males were increased in 3% exposed fish compared to those in 10% effluent. Male FHM exposed to 30% effluent had increased whole-body testosterone levels, and female FHM in 30% effluent had decreased testosterone. No differences in estradiol or 11-ketotestosterone were observed in FHM. Relatively limited response occurred in other endpoints. A comparison of the results of the present study to other published studies suggests that current reproductive bioassays are only sensitive for detecting magnitudes of change of greater than 50% and that differences exist in the sensitivities of fish. Future research should address methods of reducing variability within test populations and focus on understanding the comparative responses among species commonly used for endocrine-disrupting substance testing.
Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology, 2015
Androgens originating from pulp mill processing, sewage treatment facilities and agricultural act... more Androgens originating from pulp mill processing, sewage treatment facilities and agricultural activities have the potential for discharge into aquatic receiving environments. To assess androgen effects on reproductive endocrine status in fish in estuarine environments, male and female adult northern mummichog (Fundulus heteroclitus macrolepidotus) were exposed to an aromatizable androgen (17α-methyltestosterone; MT) and a non-aromatizable androgen (5α-dihydrotestosterone; DHT) in a short-term reproductive endocrine bioassay. Fish were nominally exposed to 10μg/L or 100μg/L DHT, or 0.1μg/L or 1μg/L MT for 14days during gonadal recrudescence. Actual concentrations of androgens, as measured by enzyme immunoassay (EIA), were 10-49% of nominal MT 0.1, 3-6% of nominal MT 1, 5-10% of nominal DHT 10 and 3-25% of nominal DHT 100. Female mummichog were impacted to a greater degree by androgen exposure, with increased plasma testosterone (T) at 100μg/L DHT, depressed plasma 17β-estradiol (E2) at both DHT concentrations and at 1μg/L MT, as well as depressed in vitro E2 at both MT concentrations and 100μg/L DHT. Males had depressed plasma T in the 10μg/L DHT treatment and depressed in vitro 11-ketotestosterone production for both MT concentrations and 10μg/L DHT. Ovarian aromatase gene expression was induced in females exposed to 1μg/L MT. DHT at 100μg/L increased hepatic vitellogenin-1 (VTG1) expression in males and depressed VTG1 expression in females. The range of responses between sexes and among species provides evidence for modes of actions and potential impacts of androgens in aquatic receiving environments.
Mining of the world's sec... more Mining of the world's second-largest nickel deposits in the area of Sudbury, Ontario, Canada, has caused acidification and metal saturation of some catchments. We conducted artificial stream studies in the years 2001 and 2002 to assess the effects of treated metal mine effluents (MMEs) from three different mining operations discharging to Junction Creek, Sudbury, on two fish species, creek chub (Semotilus atromaculatus) and pearl dace (Semotilus margarita). Treatments tested for 35 to 41 d included reference water, Garson MME (30%), Nolin MME (20%), and Copper Cliff MME (45%). In 2001, effects on chub included reduced survival and depressed testosterone levels (fivefold reduction) after exposure to all MMEs. In 2002, chub and dace survival were reduced to less than 60% in the Copper Cliff and Garson treatments. In addition, the total body weights of male and female dace were reduced after exposure to the Garson and Copper Cliff treatments. In 2001 and 2002, responses were most common to the 45% Copper Cliff and 30% Garson effluents, with consistent increases in nickel, rubidium, strontium, iron, lithium, thallium, and selenium observed across treatment waters and body tissues. More work is required to link observed effects to field effects and to identify multitrophic level responses of the ecosystem to the MMEs. The artificial stream studies provided a mechanism to identify changes in the endpoints of relevant fish species exposed to present-day metal mine discharges independent of historical depositions of metals in the Sudbury area.
Although multiple reproductive tests have been developed in small-bodied fish to determine the ef... more Although multiple reproductive tests have been developed in small-bodied fish to determine the effects of endocrine- disrupting substances, few direct comparisons have been made among the available tests. Side-by-side reproductive tests with mummichog (Fundulus heteroclitus) and fathead minnow (FHM; Pimephales promelas) were conducted with 0, 3, 10, and 30% effluent from a bleached kraft pulp mill in Saint John, New Brunswick, Canada. Egg production was significantly increased in mummichog exposed to 3% combined mill effluent, but no difference was observed in FHM. No differences were found in whole-body testosterone or estradiol levels in mummichog, and whole-body 11-ketotestosterone levels in males were increased in 3% exposed fish compared to those in 10% effluent. Male FHM exposed to 30% effluent had increased whole-body testosterone levels, and female FHM in 30% effluent had decreased testosterone. No differences in estradiol or 11-ketotestosterone were observed in FHM. Relatively limited response occurred in other endpoints. A comparison of the results of the present study to other published studies suggests that current reproductive bioassays are only sensitive for detecting magnitudes of change of greater than 50% and that differences exist in the sensitivities of fish. Future research should address methods of reducing variability within test populations and focus on understanding the comparative responses among species commonly used for endocrine-disrupting substance testing.
Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology, 2015
Androgens originating from pulp mill processing, sewage treatment facilities and agricultural act... more Androgens originating from pulp mill processing, sewage treatment facilities and agricultural activities have the potential for discharge into aquatic receiving environments. To assess androgen effects on reproductive endocrine status in fish in estuarine environments, male and female adult northern mummichog (Fundulus heteroclitus macrolepidotus) were exposed to an aromatizable androgen (17α-methyltestosterone; MT) and a non-aromatizable androgen (5α-dihydrotestosterone; DHT) in a short-term reproductive endocrine bioassay. Fish were nominally exposed to 10μg/L or 100μg/L DHT, or 0.1μg/L or 1μg/L MT for 14days during gonadal recrudescence. Actual concentrations of androgens, as measured by enzyme immunoassay (EIA), were 10-49% of nominal MT 0.1, 3-6% of nominal MT 1, 5-10% of nominal DHT 10 and 3-25% of nominal DHT 100. Female mummichog were impacted to a greater degree by androgen exposure, with increased plasma testosterone (T) at 100μg/L DHT, depressed plasma 17β-estradiol (E2) at both DHT concentrations and at 1μg/L MT, as well as depressed in vitro E2 at both MT concentrations and 100μg/L DHT. Males had depressed plasma T in the 10μg/L DHT treatment and depressed in vitro 11-ketotestosterone production for both MT concentrations and 10μg/L DHT. Ovarian aromatase gene expression was induced in females exposed to 1μg/L MT. DHT at 100μg/L increased hepatic vitellogenin-1 (VTG1) expression in males and depressed VTG1 expression in females. The range of responses between sexes and among species provides evidence for modes of actions and potential impacts of androgens in aquatic receiving environments.
Mining of the world's sec... more Mining of the world's second-largest nickel deposits in the area of Sudbury, Ontario, Canada, has caused acidification and metal saturation of some catchments. We conducted artificial stream studies in the years 2001 and 2002 to assess the effects of treated metal mine effluents (MMEs) from three different mining operations discharging to Junction Creek, Sudbury, on two fish species, creek chub (Semotilus atromaculatus) and pearl dace (Semotilus margarita). Treatments tested for 35 to 41 d included reference water, Garson MME (30%), Nolin MME (20%), and Copper Cliff MME (45%). In 2001, effects on chub included reduced survival and depressed testosterone levels (fivefold reduction) after exposure to all MMEs. In 2002, chub and dace survival were reduced to less than 60% in the Copper Cliff and Garson treatments. In addition, the total body weights of male and female dace were reduced after exposure to the Garson and Copper Cliff treatments. In 2001 and 2002, responses were most common to the 45% Copper Cliff and 30% Garson effluents, with consistent increases in nickel, rubidium, strontium, iron, lithium, thallium, and selenium observed across treatment waters and body tissues. More work is required to link observed effects to field effects and to identify multitrophic level responses of the ecosystem to the MMEs. The artificial stream studies provided a mechanism to identify changes in the endpoints of relevant fish species exposed to present-day metal mine discharges independent of historical depositions of metals in the Sudbury area.
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