Developing a Biomarker to Cold Shock in the Yellow Perch, Perca flavescens

Abstract

Fish kills are common events with their causes variously attributed to natural and anthropogenic sources. Yet, it is very difficult to properly attribute a specific cause to fish death due to many interacting variables. Utilities have found a similar problem where fish impingement events coincide with rapid reductions in water temperature. There is no clear protocol for investigating this matter to determine if cold shock is the underlying mechanism for impingement. Hence, this study focused on developing a biomarker for cold shock in fish. In this thesis I used the expression of twenty-eight genes (grouped into four categories of: stress response, endocrine disruption, growth and metabolism, and immune function genes) in yellow perch (Perca flavescens) to isolate between common stressors (heat and air exposure) and varying degrees of cold shock (exposures of 8°C, 12°C, and 16°C). I also assessed gene expression in different cold shock exposures (8°C, 12°C, and 16°C) over time (~4-5 fish sampled/hour for a maximum of ~5 hours). Several potential biomarkers for cold shock were identified: cirbp, igf1, igf2, cam, and mhcI. The expression of markers was also found to express differentially between different cold temperatures and at a single cold temperature over time. The findings of this study contribute to the knowledge gap in the literature for the field of cold shock in fish and provides a novel study where many proposed markers in the field were tested together for biomarker identification.