Influence of different temperature and body weight on Octopus vulgaris respiratory metabolism in the South China Sea

The relationship between oxygen consumption rate, ammonia excretion rate and water temperature,body weight and the respiratory metabolism of wild Octopus vulgaris in South China Sea were investigated with a breather apparatus in closed static seawater system. The experimental results showed that water temperature had apparent effect on oxygen consumption rate and ammonia excretion rate(P0.05), while the influence of weight was not significant(P0.05). Under 16 32℃, the oxygen consumption rate and ammonia excretion rate first increased and then decreased with increasing temperature; under the same temperature, no significant changes were observed among different body weight. Temperature of 24℃ may be the kick point for Octopus vulgaris respiratory metabolism. Under this temperature, the highest oxygen consumption rate,ammonia excretion rate and fastest metabolic rate were recorded. At 24℃, Octopus vulgaris oxygen consumption rate and ammonia excretion rate were 0.86 mg/(g·h) and 36.69 μg/(g·h) per unit of body mass, respectively. The result of respiratory metabolism substrate analysis showed that under 24 28℃ the ratio of O:N increased with temperature increasing, which indicated that the proportion of energy provided by protein decreased.