EFFECTS OF TEMPERATURE-CHANGE RATE ON NITROGEN EFFLUXES OF MACROBRACHIUM-ROSENBERGII (DEMAN)

Ammonia-N (NH4(+) + NH3) and total nitrogen (TN) efflux rates of Macro brachium 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 no t affect efflux rates, but sudden temperature rises evoked rapid and h igh increases in the efflux rates. A direct relationship between ammon ia-N excretion and water temperature was observed when gradual tempera ture changes were effected over a 5 h period, When the animals were ac climated to a new temperature for 72 h, no clear effects of temperatur e 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. r osenbergii should be avoided or made gradually.