Triploidy in white sturgeon (Acipenser transmontanus): Effects of acute stress and warm acclimation on physiological performance.

Previous studies have demonstrated reduced performance in triploid fish when reared under suboptimal conditions, which may be the result of a higher susceptibility to stressors when compared to diploids. The goal of this project was to investigate differences in the capacity of diploid (8 N) and triploid (12 N) white sturgeon, Acipenser transmontanus, to respond to both warm acclimation (6-weeks of acclimation to either 18 or 22 °C) and a subsequent acute stress (10-min low water stress). Following the 6-week acclimation, fish were sampled either before or following an acute low water stress. Bioindices of the primary and secondary stress response, hematology and cellular metabolic status were measured. We also sought to determine if time to peak cortisol levels were similar between diploid and triploid sturgeon after exposure to a severe acute stressor (netting stress). While both ploidies had similar primary and secondary responses to acute stress, both with and without warm acclimation, warm acclimation impacted the ability of diploid and triploid white sturgeon to mount a typical stress response to an acute stressor. In response to warm acclimation, triploids exhibited little change in branchial lactate dehydrogenase activity, while diploids increased activity. After exposure to an acute water reduction stress, diploids increased citrate synthase activity, yet triploids showed a decrease in activity. Differences in metabolic enzyme activity in response to warm acclimation and acute stress suggest triploid white sturgeon may have a reduced cellular metabolic capacity under chronic and acute stress, which may impact performance of triploid sturgeon in suboptimal conditions.