Effects of Diet on Responses to Hypoxia in Sturgeon (Acipenser Naccarii)

We investigated the effects of a diet enriched in omega-3 (ω3) polyunsaturated fatty acids (PUFA) and vitamin E on responses of sturgeon (Acipenser naccarii) to hypoxia. After 3 months of feeding, there were significant increases in ω3 PUFA in liver and muscle, and of vitamin E in muscle, of fish fed the enriched diet (ED) compared with fish on a standard diet (SD), indicating that tissue composition is influenced by diet. Acute exposure to hypoxia (10 min at 10.8 kPa water O₂ tension, Pw_O2 had no effect on oxygen consumption (V_O2, increased gill ventilation frequency (fG) and reduced arterial blood O₂ content (Ca_O2 in both dietary groups, but ED sturgeon exhibited a significantly smaller decrease in Ca_O2 than did SD animals. Progressive hypoxic exposure (Pw_O2 decreasing gradually from 20.5 to 3.6 kPa within 45–60 min) led to a significant increase in V_O2 at intermediate levels of Pw_O2 in SD sturgeon that was not seen in ED animals. Furthermore, ED sturgeon showed no significant reduction in arterial plasma pH (pHa) and Ca_O2 at Pw_O2 levels that caused significant reductions in these variables in SD sturgeon. ED sturgeon exhibited a smaller increase in plasma lactate level than did SD fish. We suggest that PUFA and/or vitamin E contribute significantly to regulation of metabolism in hypoxia.