EFFECT OF SALINITY ON OXYGEN-CONSUMPTION AND AMMONIUM EXCRETION IN MACROBRACHIUM-ROSENBERGII (CRUSTACEA, PALAEMONIDAE)

The metabolic rate of postlarvae and juvenile of Macrobrachium rosenbergii increased at low salinities because they required more energy to compensate for the accentuated osmotic gradient. Respiratory rate was constant at high salinities: less energy was used to hyperosmoconform. When salinity increased ammonia excretion increment of both stages was related to the activity of the ionic Na+/NH+4 exchange bomb to balance the Na+ levels of hemolymph. The atomic relation O:N showed that the postlarvae and juvenile prawns used carbohydrate lipid at diluted mediums and protein at high salinities.