Rogers, Sean MichaelLai, Carina M.2025-01-092025-01-092025-01-03Lai, C. M. (2025). Impacts of sedimentation on early-life phenotypes and gene expression in coho salmon (oncorhynchus kisutch) (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.https://hdl.handle.net/1880/120390Early-life environmental stressors may threaten species of conservation concern by impacting populations during vulnerable early life history stages. Here, I tested some of the effects of sediment stress and hypoxia during early-life development on phenotypic outcomes and gene expression in coho salmon (Oncorhynchus kisutch). I obtained O. kisutch eggs from the Sugsaw Hatchery located on Vancouver Island, BC, and reared them in one of three substrate (0% fine sediment, 10% fine sediment, 20% fine sediment) or one of two no substrate (normoxia/100% DO or hypoxia/50% DO) treatments to the alevin stage (n=180 per treatment). Survival did not differ between groups, but fish reared in hypoxia and 20% fine sediment exhibited significantly lower fork lengths and weights. Yolk sac area and volume were also lower in fish from the 20% fine sediment treatment, suggesting a decrease in yolk sac conversion efficiency. Gene expression analysis of three general (HIF1A_6, ALD_1, HemA1_1) and four hypoxia-specific (Anillin, Ncapd3, Ndc80, Kif4) biomarkers revealed significant upregulation of ALD_1 expression in hypoxia-reared fish, while fewer significant differences were detected in the remaining biomarkers. Overall, more research is necessary to elucidate the genomic mechanisms mediating the phenotypic changes that result from exposure to hypoxia and high sedimentation in early-life salmonids. Yet these findings suggest that there may be negative consequences of sedimentation and hypoxia during early-life salmonid development and that these are driven by complex molecular interactions that underlie early-life organisms’ responses to stress. Reduced growth and yolk sac conversion efficiency in fish reared without substrate, compared to high quality substrate further suggest that substrate environmental enrichment (EE) during early-life rearing may be beneficial for salmonids artificially reared in hatcheries.enUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.EcologyFisheries and AquacultureBiology--Molecularmaster thesis