The energetic impacts of environmental variability associated with overwintering in temperate and polar char (Salvelinus spp.)
University of New Brunswick
Poleward winters are characterized by frigid temperatures and low food availability that can affect the energetic capacity and requirements of fishes. I investigated the physiological flexibility to cold and food deprivation in two cold-adapted salmonid fishes to understand how winter conditions affect energy expenditure and metabolic performance. Brook char (Salvelinus fontinalis) showed remarkable thermal compensation of standard metabolic rate (ṀO2standard) in response to cold acclimation. Food deprivation, however, markedly lowered ṀO2standard, and this was associated with depression of protein synthesis rates and tissue-specific atrophy. Reductions in ṀO2standard did not compromise aerobic capacity, as maximum metabolic rate was unchanged with food deprivation. Similarly, following prolonged natural starvation over winter, wild anadromous Arctic char (Salvelinus alpinus) lowered their resting metabolic demands while conserving aerobic capacity. Overall, my studies highlight the marked and multi-faceted energetic flexibility of Salvelinus spp. that is likely central to their success in harsh and variable environments.