Effects of temperature on growth, oxygen consumption and thermal tolerance of juvenile humpback grouper Cromileptes altivelis
ZHANG Shanfa1, DONG Hongbiao2, WANG Qian1, ZHANG Jiasong2*
1.School of Environment and Energy, Peking University Shenzhen Graduate School, Shenzhen 518055，China; 2.Key Laboratory of South China Sea Fishery Resources Exploitation & Utilization, Ministry of Agriculture and Rural Affairs， South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510300, China
Abstract: Juvenile humpback grouper Cromileptesaltivelis with body mass of (21.38±1.27) g were divided into three groups, and reared in 9 fiberglass tanks of each 1 m3 at initial density of 30 fish per tank at (24±1)℃(low temperature group), (28±1)℃(median temperature group), and (32±1)℃(high temperature group)for 56 days with 3 replicates. Then the growth, oxygen consumption rate and thermal tolerance were compared among groups in order to investigate the effects of temperature on growth, oxygen consumption rate and thermal tolerance of humpback grouper. The results showed that humpback grouper had good growth at water temperature between 24 and 32 ℃, with the best growth rate of (55.81±8.15)% at 28 ℃, significantly higher than those at 24 ℃ and 32 ℃ (P<0.05). The oxygen consumption rate and suffocation point were shown to be elevated with the increase in water temperature, with the oxygen consumption rate of (0.20±0.01)mg/(g·h) and suffocation point of (1.55±0.04)mg/L at 24 ℃, oxygen consumption rates of (0.23±0.02)mg/(g·h) and suffocation point of (1.81±0.06)mg/L at 28 ℃, and oxygen consumption rates of (0.28±0.02) mg/(g·h), and the suffocation point of (2.18±0.12)mg/L at 32 ℃. Q10 analysis indicated that the fish was more sensitive to the temperature change at high temperature range (28-32 ℃) compared with low temperature range (24-28 ℃), increase in the critical tolerance temperature with the warming water temperature, with the maximum critical temperature (θC,h) of 37.12-41.05 ℃ and minimum critical temperature (θC,l) of 12.70-17.76 ℃. The less sensitive to the rising water temperature was observed in the juveniles exposed to normal water temperature than that in the juveniles exposed to the experimental conditions. There was significantly higher expression of HSP70 protein in the liver and the gill in the fish at 32 ℃ than that at the other temperatures. It was concluded that the oxygen consumption rate and asphyxial point of humpback grouper were increased with warming temperature, inhibition of growth at high temperature of 32 ℃, and the best survival and growth rate at water temperature of 28 ℃.
2021, Vol. 36 
