OSMORREGULATIN AND GROWTH FIELD OF MACROB RACHIUM-ROSENBERGII (CRUSTACEA, PALAEMONIDAE)

The postlarvae and juveniles of the Malaysian prawn Macrobrachium rose nbergii kept at several salinities showed a remarkable osmoregulatory capacity similar to that reported for other species of the genus. Both stages had a hyperosmotic regulation pattern in diluted mediums. in w hich they maintained a 442 to 542 mOsm concentration of the hemolymph. Above these salinities, the osmolality of the hemolymph of both stage s increased and remained hyperosmoconforming on the extreme concentrat ion of 450 mOsm. When salinity increased from 0 to 20 parts per thousa nd, there was a decrease (P < 0.05) in postlarvae growth potentiality from 68.7 cal/individual/day to 10.3. and from 145 to 12.9 cal/individ ual/day in juveniles. Areas with brackish waters (salinities between 1 0 to 20 parts per thousand) am not adequate for the commercial-scale c ulture of Macrobrachium rosenbergii, because the growth mte is reduced in high salinities.