Effects of temperature and salinity on oxygen consumption and ammonia-N excretion of juvenile Penaeus japonicus Bate

Abstract

Both oxygen consumption (O2 mg/g/h) and ammonia-N excretion rates (μg/g/h) of Penaeus japonicus Bate juveniles (0.220 ± 0.051 g) increased with an increase of temperature in the range of 15–35 °C at four salinity levels (15, 20, 25 and 30%0). Oxygen consumption decreased with increase of salinity in 15 and 25 °C, however, differences in oxygen consumption among salinity treatments were not significant at 35 °C. Ammonia-N excretion of shrimp significantly decreased with an increase of salinity in all temperatures tested. Relationships among oxygen consumption (OC), ammonia-N excretion (AE), temperature (T), salinity (S) and exposure time (t) are as follows: OC= −0.0359 + 0.0235 T −0.0024 S −0.0043 t (r2 = 0.7464) and AE = 5.4183 + 2.2379 T − 1.2731 S −0.2123 t (r2 = 0.7939). The O:N ratio suggested a shift of nutrient utilization from protein-dominated to lipid-dominated metabolism for P. japonicus, when they were subjected to increased salinity of 30%. at 15°C.