Date of Award

8-2010

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Biology

Supervisor

J. Y. Wilson

Language

English

Abstract

The occurrence of endocrine disruption in aquatic species is of growing concern in the Great Lakes region. Feminized male white perch (Morone americana) and round goby (Neogobius melanostomus) have been observed in Hamilton Harbour, a heavily polluted embayment of Lake Ontario. The harbour is impacted by wastewater effluent, containing pharmaceuticals and natural steroid hormones, as well as sediment-bound industrial contaminants including polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). This study investigated the severity of endocrine disruption in Hamilton Harbour in an attempt to identify which areas of the harbour are most heavily impacted and thereby, which contaminants are the most potent endocrine disrupting chemicals (EDCs). The round goby, an invasive species found throughout the Great Lakes region, was used as the model species. Three biological endpoints in male fish were observed: intersex (the presence of oocytes in male gonads), feminization of secondary sexual characteristics, and vitellogenin (Vtg) gene upregulation. Vtg is an egg yolk precursor protein normally highly expressed in reproductively active females. Vtg qPCR assays were developed and tested using an in vivo lab exposure to estradiol, a known Vtg-inducing compound. Field studies looked for site differences and revealed that there were significant differences among sites in all three biological endpoints. More heavily impacted sites had high signals from each endpoint while moderately impacted sites displayed Vtg upregulation and feminization of secondary sexual characteristics, but not intersex. As expected, reference sites were not impacted by endocrine disruption. Sites influenced primarily by wastewater effluent were moderately impacted, suggesting that wastewater effluent is not the dominant endocrine dismpting agent in the harbour. Sites that were most heavily impacted were those characterized by high sediment PAH and/or PCB levels. PAHs and PCB appear to be the most potent EDCs in the Hamilton
Harbour.

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