| Summary: | Thesis (M.Sc.)--Memorial University of Newfoundland, 2001. Biology Bibliography: leaves 117-125 A study was conducted to determine the impact of petroleum hydrocarbons on pearl dace, Margariscus (=Semotilus) margarita, inhabiting stillwaters (SW) 1-4 of the Spring Gulch Wetlands, Canadian Forces Base Goose Bay, Labrador. The results often (10) biomarkers were compared to results for pearl dace captured from three reference sites (Rl-3) at varying distances from CFB Goose Bay. -- Evidence supporting the premise that the extinction of pearl dace from the Spring Gulch Wetlands as a consequence of the chronic effects of petroleum hydrocarbon contamination was collected. The petroleum hydrocarbon contaminant levels in SW1,3 and 4 impaired reproduction in pearl dace populations. There was a predominance of female fish in SW1,3 and 4 and they were producing mature eggs in 1995 but none had spawned. There were none, or very few, juvenile fish in SW1,3 and 4, suggesting reproductive failure and/or low reproductive survival rates. Fish collected from SW1,3 and 4 were also longer, heavier and had higher condition factors than fish sampled from three reference sites (Rl-3). There were more, and greater degrees, of histopathological lesions in fish sampled from SW1,3 and 4 compared to the reference sites. These lesions included interlamellar hyperplasia, hepatic lipid vacuolation, pigmented and non-pigmented splenic melanomacrophage aggregates and significant splenic concentrations of hemosiderin. Mixed function oxygenase activity (7-EROD) was elevated only in samples of liver taken from pearl dace from SW4 in 1996 but not in 1995. It is possible that estrogenic hormonal levels disrupted 7-EROD induction in 1995. -- The absence of juvenile fish, high prevalence of histopathological lesions, delay in seasonal maturity, and the complete disappearance of pearl dace from SW1,2 and 3 over the two-year study period suggests that the pearl dace population at SW4 also faces eventual extinction.
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