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Effects of phytosterols and estradiol on maturation and reproduction in fathead minnows

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dc.contributor.advisor Solomon, Keith R.
dc.contributor.advisor Parrott, J.L. Knutson, Sean 2020-12-08T16:40:34Z 2020-12-08T16:40:34Z 1998
dc.description.abstract Phytosterols have been detected in the dissolved portion of secondary treated pulp and paper mill effluent at concentrations of approximately 100 to 300 ug/L. $\beta$-sitosterol, which represents approximately 90% of the phytosterols in effluent, resembles the female hormone 17$\beta$-estradiol. It has been hypothesized that the release of $\beta$-sitosterol from pulp and paper mills may contribute to adverse impacts on fish reproduction. Juvenile fathead minnows (Pimephales promelas) were exposed to either a waterborne mixture of phytosterols (containing mainly $\beta$-sitosterol) or pure estradiol in a partial life-cycle test to determine if phytosterols could alter secondary sex characteristics, gonadosomatic index (GSI), gonadal sex steroid concentrations, or egg production. 17$\beta$-estradiol (0.25 ug/L) caused a delay in the onset of secondary sex characteristics in male fish. Graded, nominal, concentrations of phytosterols (3-100 ug/L) did not cause a significant difference in fathead minnow maturation or egg production. Egg production was highly variable between early and late spawning control fish, indicating that many replicates may be needed for this endpoint to be of use. Once fathead minnows matured sexually in estradiol and phytosterol treatments, they had GSI and gonadal sex steroid concentrations comparable to those of control fish. Although phytosterols are present in pulp and paper mill effluent, the concentrations tested here show no adverse effects on sexual maturation and egg production in fathead minnows. However, the response to 17$\beta$-estradiol shows the potential of this fathead minnow partial life-cycle test to detect estrogenic substances.
dc.language.iso en
dc.publisher University of Guelph en_US
dc.subject phytosterols
dc.subject estradiol
dc.subject maturation
dc.subject reproduction
dc.subject fathead minnows
dc.subject Pimephales promelas
dc.subject pulp and paper mill effluent
dc.title Effects of phytosterols and estradiol on maturation and reproduction in fathead minnows
dc.type Thesis en_US Master of Science en_US Department of Environmental Biology en_US
dc.rights.license All items in the Atrium are protected by copyright with all rights reserved unless otherwise indicated. University of Guelph en_US

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