Effects of Low Salinity acclimation on Oxygen Consumption in Giant Grouper, Epinephelus lanceolatus

Abstract

Changes of oxygen consumption in juvenile giant grouper, Epinephelus lanceolatus were investigated in order to find out the physiological responses associated with freshwater and low salinities acclimation. Salinity changes in this experiment were set as follows; 35 psu (Exp.) as control, decrease in the Ⅰ manners of 35 20 10 0 psu (Exp. ), 35 10 0 psu (Exp. ) and 35 0 psu (Exp. ). The average → → → Ⅱ → → Ⅲ→ Ⅳ oxygen consumption at 27 in Exp.(control) was 106.9±0.7 mg ℃ Ⅰ   /kg/h. In Exp. , according to the Ⅱ changes of 35 20 10 0 psu in freshwater acclimation, fish showed the gradual decrease in oxygen → → → consumption as 108.1±2.1, 99.6±2.9, 74.6±0.9 and 62.7±1.0 mg   /kg/h, respectively. The fish in Exp. Ⅲalso revealed the same tendency as 106.5±1.3, 77.0±1.2 and 64.7±1.2 mg   /kg/h, respectively. In Exp. , Ⅳ fish showed the decreased oxygen consumption from 109.0±0.9 mg   /kg/h of 35 psu to 71.6±2.0 mg   /kg/h of 0 psu. Giant grouper is thought to be a diurnal fish species, because the level of oxygen consumption during light period was higher than that during dark period.