Variation in fish fatty acid concentrations among lakes in the Dehcho region of the Northwest Territories

• Main Author: Boag, Tara
• Format: Master Thesis
• Language: English
• Published: University of Waterloo 2020
• Subjects: fatty acids; freshwater fish; mercury; Dehcho Region; Northwest Territories; Subarctic
• Online Access: http://hdl.handle.net/10012/16594

Background: In the subarctic Dehcho region of the Northwest Territories, many remote communities rely on traditional foods, including fish, to supplement more expensive store-bought options. Fish are an excellent source of omega-3 and omega-6 polyunsaturated fatty acids (n-3 and n-6 PUFAs, respectively), essential compounds that can only be obtained through the diet. Long-chain n-3 PUFAs, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are especially important for human health. As the health benefits derived from consuming fish can be diminished by the risk imposed by exposure to contaminants, such as mercury, researchers and communities in the Dehcho region began a collaborative project in 2012 to quantify both fatty acid and mercury concentrations in fish. In the course of this work, it was found that concentrations of fatty acids in fish differed significantly among lakes in the Dehcho region. In freshwater ecosystems, fatty acids are produced by algae and bacteria and transferred up the food chain through consumption. The type and quality of fatty acids produced varies among primary producer taxa, meaning that fatty acid profiles in fish may vary among lakes due to variation in the composition of algal and bacterial communities, which in turn vary in response to abiotic conditions in lakes. Objectives: As some fish samples were stored for multiple years before processing, the first objective of this study was to determine if there was a relationship between concentrations of fatty acids and storage time at -20 degrees C. After determining which fatty acids were affected by storage time and how they were affected by storage time, the second objective was to update existing fish fatty acid profiles (analysed from samples collected 2013-2015) for the study lakes. The third objective was to determine whether there were differences in concentrations among lakes for several fatty acid groups of interest, including total fatty acids (TFA), n-3 and n-6 PUFAs, DHA, and EPA, and whether observed ...