EFFECTS OF DIET ON SPONTANEOUS LOCOMOTOR-ACTIVITY AND OXYGEN-CONSUMPTION IN ADRIATIC STURGEON (ACIPENSER NACCARII)

Adriatic sturgeon (Acipenser naccarii) were maintained on a commercial diet enriched either in long chain polyunsaturated fatty acids of the omega 3 series (omega 3 LCPUFA) or in saturated fatty acids (SFA). The effects of dietary fatty acid composition on spontaneous locomotor activity in normoxia and hypoxia (O-2 tension = 10.5 +/- 0.8 kPa), and on oxygen consumption (M(O2)) in normoxia, in hypoxia (O-2 tension = 6.6 +/- 0.8 kPa) and during recovery were then investigated. The effects of adding supplementary vitamin E to the fat-enriched diets were also studied. Dietary fatty acid composition had effects on spontaneous locomotor activity and M(O2) in normoxia. Activity levels were higher in all sturgeon fed extra dietary fats (without vitamin E), when compared with control animals, but fish fed omega 3 LCPUFA had a significantly lower M(O2), than those fed SFA, with intermediate M(O2) in controls. In hypoxia, sturgeon omega 3 LCPUFA did not alter activity or M(O2) whereas those fed SFA reduced both and controls reduced M(O2). During recovery, both animals fed SFA and controls had a higher M(O2) than sturgeon fed omega 3 LCPUFA. The data indicate that fish fed omega 3 LCPUFA are more tolerant of hypoxia than controls or those fed SFA, as they did not reduce either activity or M(O2), and consumed less O-2 during recovery. Vitamin E supplements modified the effects elicited by dietary fats. All sturgeon fed vitamin E had low activity levels in normoxia and hypoxia. Sturgeon fed vitamin E with omega 3 LCPUFA had a higher M(O2) in normoxia than those fed omega 3 LCPUFA alone; reduced MO(2) in hypoxia, and during recovery increased M(O2) to a rate higher than that of animals fed omega 3 LCPUFA alone. In normoxia, sturgeon fed vitamin E with SFA had a similar M(O2) to those fed SFA alone but did not change MO(2) in hypoxia or during recovery. Thus, the effects of vitamin E were dependent on fat composition of the diet. Vitamin E with omega 3 LCPUFA removed the beneficial effects on M(O2) and responses to hypoxia obtained with omega 3 LCPUFA alone, but vitamin E with SFA allowed sturgeon to maintain aerobic metabolism in hypoxia, a more effective response than that observed in fish fed SFA alone.