Hemolymph oxyhemocyanin, protein, osmolality and electrolyte levels of whiteleg shrimp Litopenaeus vannamei in relation to size and molt stage

The whiteleg shrimp Litopenaeus vannamei (Boone, 1931) was examined for hemolymph oxyhemocyanin, protein, osmotic and ion concentrations in relation to sex, size and molt stage. No significant difference in hemolymph variables was observed between male and female shrimp with body weight in the range of 4.69-32.57 g. With regard to the molt cycle, hemolymph protein and oxyhemocyanin levels were highest (132.56 +/- 2.79 mg/ml and 1.70 +/- 0.04 mmol/l) at stage D-0/D-1, and lowest (87.54 +/- 2.28 mg/ml and 1.08 +/- 0.05 mmol/l) at stage A, respectively. Hemolymph osmolality and chloride concentration was highest (798 +/- 6.3 mOsm/kg and 276.8 +/- 2.2 mmol/l at stage D-0/D-1, and lowest (760.7 +/- 2.8 mOsm/kg and 241.5 +/- 3.8 mmol/l) at stage A. Increases in hemolymph protein, oxyhemocyanin, osmolality, Cl-, Na+, K+, Mg2+ and Ca2+ levels with size indicated that the shrimp mature in the culture ponds. The fact that the hemolymph protein, osmolality, Cl-, Na+ and K+ levels were lower during the postmolt, but higher during intermolt and early premolt can be associated with water uptake at molt. (C) 2002 Elsevier Science B.V. All rights reserved.