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<p>Hamilton Harbour is one of the most polluted sites on the Great Lakes, affected by airborne and sedimentary contamination as a result of both heavy vehicle traffic and thousands of kilograms of industrial steel emissions. Polycyclic Aromatic Hydrocarbons (PAHs) are ubiquitous mutagenic byproducts of incomplete organic combustion; they are present at very high concentrations in the air and sediment of Hamilton Harbour. We quantified DNA mutation rates in three different nesting colonies of Double-crested Cormorants (<em>Phalacrocorax auritus</em>) using five microsatellite markers. These colonies were located at various distances from sources of PAHs and other contamination. We compared pollution-exposed and reference colonies, hypothesizing that cormorants living closest to pollution will have higher rates of germline microsatellite mutations than those living farther away from pollution sources. Using a pedigree approach, we identified mutations when chicks showed microsatellite alleles not found in either parent, and other explanations such as extra-pair parentage had been ruled out. Microsatellite mutation rates were 4.4 times higher at the Hamilton Harbour site closest to the industrial sources of PAH contamination than the other Hamilton Harbour site, and both were higher than the reference colony. Metabolites of the PAH benzo[a]pyrene in cormorant tissues from both Hamilton Harbour sites were identified by LC-MS/MS, demonstrating that cormorants in Hamilton Harbour are exposed to, and metabolizing, PAHs. Diet was not substantially different between the two Hamilton Harbour colonies when measured with regurgitated samples and fatty acid analysis. This suggests airborne pollution in Hamilton Harbour induced germline mutations in cormorants.</p> / Master of Science (MSc)

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Increasing awareness about the presence and ecological ramifications of toxic, persistent and bioaccumulative contaminants within the Great Lakes system spurred the implementation of numerous bans and emissions restrictions over the past few decades. Due to their high trophic status in food webs and the critical link they serve with human consumers, fish species have historically been monitored to assess the relative success of such remedial efforts within the region and to simultaneously ascertain the current risks posed to local humans. Using Bayesian dynamic linear modelling, this project first aimed to evaluate temporal trends of various organochlorine contaminants within Lake Erie fish communities, the results of which generally indicated decreasing trends through time. The second half of this study used a similar Bayesian approach to propose a framework for updating fish consumption advisories, with specific attention paid to the acknowledgment of uncertainty and natural variability when producing such consumption guidelines.

Increasing awareness about the presence and ecological ramifications of toxic, persistent and bioaccumulative contaminants within the Great Lakes system spurred the implementation of numerous bans and emissions restrictions over the past few decades. Due to their high trophic status in food webs and the critical link they serve with human consumers, fish species have historically been monitored to assess the relative success of such remedial efforts within the region and to simultaneously ascertain the current risks posed to local humans. Using Bayesian dynamic linear modelling, this project first aimed to evaluate temporal trends of various organochlorine contaminants within Lake Erie fish communities, the results of which generally indicated decreasing trends through time. The second half of this study used a similar Bayesian approach to propose a framework for updating fish consumption advisories, with specific attention paid to the acknowledgment of uncertainty and natural variability when producing such consumption guidelines.