Effect of Different Oxygen Concentrations on Physiological Energetics of Blue Shrimp, Litopenaeus stylirostris (Stimpson)

ABSTRACT

The influence of different oxygen concentrations on the bioenergetics parameters, osmoregulatory capacity and O:N atomic ratio of the blue shrimp, Litopenaeus stylirostris (Stimpson), was determined under laboratory conditions; shrimp were acclimated at 28 °C and 25psu and exposed to three different oxygen concentrations 2, 4 and 6 mg L^-1. The critical oxygen level (COL) was determined at 5.5 mg L^-1. Growth, oxygen consumption (R), ammonium excretion (U), scope for growth (P) and apparent heat increment (AHI) were affected significantly (P < 0.05) when the organisms were exposed at different oxygen concentrations. The highest energy invested for routine metabolism and ammonium excretion was obtained in the animals maintained at 2 mg L^-1. The exposure of organisms to oxygen concentration (2 mg L^-1) increased three times the feces production (23.59%). The high quantity of energy channeled to scope for growth (2756 J g^-1 day^-1 d.w.) was obtained in the shrimp acclimated to an oxygen concentration of 6 mg L^-1. The O:N atomic ratio calculated for the juveniles indicated a catabolism of proteins for the organisms maintained in the lowest oxygen concentration. In the oxygen concentrations of 2 and 4 mg L^-1 the blue shrimp juveniles modified their osmoregulatory capacity (OC) changing the osmoregulatory pattern the isosmotic to hypo-osmotic. We recommend maintaining Litopenaeus stylirostris at 6 mg L^-1 and (25psu), these conditions for blue shrimp juveniles would enhance production in the cultivation of this species.

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