The effect of salinity on the osmotic and ionic concentrations in the hemolymph of Penaeus monodon and P. penicillatus. In：J.L. Maclean, L.B. Dizon and L.V. Hosillos (eds.)

Abstract

The osmoregulation of juvenile and adult Penaeus monodon and P. penicillatus and the ionic regulation of the adults, were investigated over a salinity range of 3-50 ppt. P. monodon was found to be a stronger osmotic and ionic regulator than P. pencillatus. The juveniles of both species are stronger osmoregulators than adults. The salinity ranges over which osmoregulations were performed efficiently were 3-50 ppt for juvenile P. monodon, 15-50 ppt for adult P. monodon, 5-30 ppt for juvenile P. penicillatus and 15-30 ppt for adult P. penicillatus. The isosmotic points were 730, 750, 747 and 800 mOsm/kg, respectively. The curves of sodium, chloride and potassium corresponded to those for the osmotic concentration of adults. The respective isoionic points for P. monodon and P. penicillatus were 352 mEq/1, 348 mEq/1 for sodium; 320 mEq/1, 304 mEq/1 for chloride; and 7.1 mEq/1, 6.1 mEq/1 for potassium. Calcium was accumulated in both species, while magnesium levels were strongly reduced. P. monodon may be the strongest osmoregulator among the Penaeus species so far studied.