The respiration, excretion and biochemical response of the juvenile common Chinese cuttlefish, Sepiella maindroni at different temperatures

Abstract

The present study was designed to measure the oxygen consumption, ammonia excretion, stress resistance, energy utilization, and osmoregulatory ability of cuttlefish Sepiella maindroni, an important cultured species of China, at different temperatures. Juvenile cuttlefish were exposed to temperatures of 16, 20, 24, 28, and 32°C for 10days, respectively. Oxygen consumption (R) rates increased significantly from 16 to 28°C and then, slightly decreased at 32°C (P<0.05). Ammonia excretion (U) rates increased with increasing temperature. The highest R Q10 and U Q10 values occurred within 16 and 20°C, and the intermediate R Q10 and U Q10 values were found within 24 and 28°C. The calculated R Q10 dropped to minimum values within 28 and 32°C which suggested that treated groups with temperature of 32°C were under a stressful situation. The suffocation point (SP) and SP/SD (suffocation duration) increased significantly with increasing temperature, and peaked at 28°C, then dropped to the minimum level at 32°C. The SD decreased significantly with increasing temperature. The hemolymph total protein concentration decreased significantly from 16 to 24°C and then increased significantly, reaching a maximum at 32°C. Hepatic superoxide dismutase (SOD) activity was significantly low at 32°C than that of at other temperatures. The lowest and highest branchial Na+, K+-ATPase activity, and Na+ and Cl− contents occurred at 24 and 28°C, respectively. The present results indicate that temperature can modify certain physiological parameters and by enhancing oxygen utilization, optimal temperatures significantly contribute to higher growth rates. It is suggested that the protein increase in the hemoglobin below and above 24°C, will lead to an increase of energy expenditure from protein as an adjustment to temperature changes. Moreover, extremely high temperatures may result in adverse effects on juvenile S. maindroni that are related to ammonia-N and oxidative stress.