Effect of dissolved oxygen on swimming ability and physiological response to swimming fatigue of whiteleg shrimp (Litopenaeus vannamei)

The swimming endurance of whiteleg shrimp (Litopenaeus vannamei, 87.66 mm +/- 0.25 mm, 7.73 g +/- 0.06 g) was examined at various concentrations of dissolved oxygen (DO, 1.9, 3.8, 6.8 and 13.6 mg L-1) in a swimming channel against one of the five flow velocities (v (1), v (2), v (3), v (4) and v (5)). Metabolite contents in the plasma, hepatopancreas and pleopods muscle of the shrimp were quantified before and after swimming fatigue. The results revealed that the swimming speed and DO concentration were significant factors that affected the swimming endurance of L. vannamei. The relationship between swimming endurance and swimming speed at various DO concentrations can be described by the power model (nu center dot t (b) = a). The relationship between DO concentration (mg L-1) and the swimming ability index (SAI), defined as SAI = a << (0) (9000) vdt, can be described as SAI = 27.947 DO0.137(R (2) = 0.9312). The level of DO concentration directly affected the physiology of shrimp, and exposure to low concentrations of DO led to the increases in lactate and energetic substrate content in the shrimp. In responding to the low DO concentration at 1.9 mg L-1 and the swimming stress, L. vannamei exhibited a mix of aerobic and anaerobic metabolism to satisfy the energetic demand, mainly characterized by the utilization of total protein and glycogen and the production of lactate and glucose. Fatigue from swimming led to severe loss of plasma triglyceride at v (1), v (2), and v (3) with 1.9 mg L-1 DO, and at v (1) with 3.8, 6.8 and 13.6 mg L-1 DO, whereas the plasma glucose content increased significantly at v (3), v (4) and v (5) with 3.8 and 6.8 mg L-1 DO, and at v (5) with 13.6 mg L-1 DO. The plasma total protein and hepatopancreas glycogen were highly depleted in shrimp by swimming fatigue at various DO concentrations, whereas the plasma lactate accumulated at high levels after swimming fatigue at different velocities. These results were of particular value to understanding the locomotory ability of whiteleg shrimp and its physiological changes, further contributing to the improvement of capture and rearing technique.