Survival rate and oxygen consumption patterns with respect to salinity changes in juvenile abalone Haliotis discus hannai

Abstract

The effects of salinity tolerance on survival and oxygen consumption were examined in the abalone Haliotis discus hannai with changes in water temperature and salinity in an indoor rearing system. The survival rate of the control group at 15°C was 100% (Expt. I, 35 psu). In Expt. II, changing the salinity from 35→30→25→20→15 psu, the survival rates were 100 ± 0.0, 100 ± 0.0, 100 ± 0.0, 98.3 ± 2.9, and 95.0 ± 0.0%, respectively. In Expt. III, for salinities of 35→25→15 psu, the rates were 100 ± 0.0, 100 ± 0.0, and 32.5 ± 2.0%, respectively. In Expt. IV, with a sharp salinity change from 35→15 psu, the rates were 100 ± 0.0 and 20.0 ± 2.9%, respectively. The average oxygen consumption at 15°C was 137.6 ± 0.5 mg O2/kg/h in Expt. I. In Expt. II, the oxygen consumption decreased gradually from 136.7 ± 2.0 to 103.2 ± 3.5 to 96.9 ± 3.2 to 88.7 ± 4.5 to 82.9 ± 3.6 mg O2/kg/h, respectively. Abalone in Expt. III showed the same tendency (i.e., 134.4 ± 1.5, 111.2 ± 3.4, and 93.2 ± 6.1 mg O2/kg/h, respectively). In Expt. IV, the oxygen consumption decreased from 141.4 ± 4.0 mg O2/kg/h at 35 psu to 99.0 ± 7.7 mg O2/kg/h at 15 psu. The tendency was the same in the experiments conducted at 20 and 25°C. Survival was reduced at salinities below 20 psu, and the mortality rate of abalone increased with a sudden salinity change and at high water temperatures.