Critical dissolved oxygen level to Penaeus setiferus and Penaeus schmitti postlarvae (PL10-18) exposed to salinity changes

Abstract

Dissolved oxygen is the most important limiting factor in the intensive cultivation of shrimp species. The critical oxygen level and its effects upon the energy metabolism of postlarvae (PL10-18) Of Penaeus setiferus and Penaeus schmitti exposed to diverse salinities were estimated. In both species the critical oxygen level (COL

estimated as the point of inflection of the curve obtained from the relation between the oxygen consumption and the oxygen concentration) was affected by salinity concentration, In P. schmitti, the COL was 5 mg l(-1) for salinities of 38, 30, 20 and 15 parts per thousand, and 4.5 mg l(-1) for animals kept at 25 parts per thousand salinity. In P. setiferus, the COL was 5.0 mg l(-1) in 37, 30, 25, 20 and 10 parts per thousand salinities and 4.5 mg l(-1) in 15, 5 and 1 parts per thousand salinities. The energy deficit (END

deficit of metabolic energy) caused by the metabolic oxygen critical concentration was in P. schmitti 13.9% (38 parts per thousand salinity) and 26.3% (30 parts per thousand salinity), with intermediate values of 17.2, 22.7 and 24.7% in 25, 20 and 15 parts per thousand salinities, respectively, I:or P. setiferus, the END was between 9.1% (1 parts per thousand salinity) and 25.1% (30 parts per thousand salinity), with intermediate values for the remaining salinities, Based on these data, the optimum salinity for P, setiferus postlarvae was between 5 parts per thousand and 15 parts per thousand, and was 25 parts per thousand for P. schmitti postlarvae. At these salinities the tolerance for the decrease in the oxygen concentration was greater than in the rest of the salinities, The high COL obtained for the postlarvae of both species indicates that the culture conditions must be carefully maintained at this developmental stage to obtain the maximum metabolic performance of the shrimp. (C) 1997 Elsevier Science B.V.