Effects of temperature and diet on the metabolic phenotypes of lake sturgeon, Acipenser fulvescens: implications for conservation aquaculture

The environment during early life history strongly impacts phenotypic development in all organisms, which further influences developmental trajectory and ecological fitness later in life. Depending on the developmental stage and magnitude of change in the environment, phenotypes may become irreversible and thus have a long-lasting effect later in life. This thesis was designed to better understand how changes in the environment may influence plasticity and variation of metabolic phenotypes of Lake Sturgeon (Acipenser fulvescens) within the first year of life. Broadly speaking, the thesis tested two hypotheses that 1) all measured phenotypes would be plastic; and 2) durations of environmental effects on phenotypic development would be correlated with distinct developmental windows. Studies were developed to examine 1) short-term effects of temperature or diet on metabolic phenotypes such as metabolic rate, energy density, fatty acid profiles, and growth (Chapters 2 and 3) and 2) longer-term effects of temperature or diet during early life on these metabolic phenotypes (Chapters 4, 5 and 6). The first experimental chapter (Chapter 2) examined ontogenetic development of metabolic rate and demonstrated that dietary shifts between Artemia to bloodworm resulted in cessation of growth with elevated routine metabolic rate. Chapter 3 examined how fatty acid profiles and plasma cortisol concentration were influenced by environmental temperature and showed that decreasing temperature led to increases in mono- and polyunsaturated fatty acids in both phospholipids and triglycerides, and food deprivation resulted in lack of difference between baseline and peak cortisol concentrations. Chapter 4 examined how temperature during early life influenced plasticity of growth and showed that temperature post-dietary transition resulted in a transient effect on growth and energy metabolism without long-term effects post-winter. Chapter 5 examined how temperature during early life could in