Effects of temperature change rate on nitrogen effluxes of Macrobrachium rosenbergii (DeMan)

Ammonia-N (NH4(+) + NH3) and total nitrogen (TN) efflux rates of Macrobrachium rosenbergii were measured during stepwise temperature changes (26 degrees C --> 22 degrees C --> 18 degrees C --> 22 degrees C --> 26 degrees C) at different rates. Sudden temperature reductions did not affect efflux rates, but sudden temperature rises evoked rapid and high increases in the efflux rates. A direct relationship between ammonia-N excretion and water temperature was observed when gradual temperature changes were effected over a 5 h period, When the animals were acclimated to a new temperature for 72 h, no clear effects of temperature on the efflux rates were found. Sudden temperature changes resulted in an increased proportion of ammonia-N in the total nitrogen excreted, It is suggested that temperature changes during the shipment of M. rosenbergii should be avoided or made gradually.