Oxygen consumption and ammonia excretion of Octopus vulgaris (Cephalopoda) in relation to body mass and temperature

The common octopus, Octopus vulgaris Cuvier, is of great scientific and commercial importance and its culture is becoming an area of increasing interest. In this study, the combined effects of temperature ( T) and body mass ( M) on the routine oxygen consumption rate ( R) and ammonia excretion rate ( U) in O. vulgaris were quantified. The experiments were conducted in a closed seawater system, and great care was taken to reduce handling stress of the animals. Temperature, salinity, pH and ammonia, nitrite, nitrate and phosphate concentrations were monitored and controlled during the experiment. The following predictive equations were evaluated: R(mulmol h(-1)) = e(25.24 - 6952.8/Ta) x M-0.901 at temperatures between 13 degreesC and 28 degreesC and U (mumol h(-1)) = e(14.77 - 4324.7/Ta) x M-0.896 at temperatures between 15.5 degreesC and 26 degreesC (T-a is degrees Kelvin and M in gram). O/N ratios showed that O. vulgaris has a protein-dominated metabolism. No significant relationship between the O/N ratio and body mass or temperature was found. Sex had no significant effect on the oxygen consumption rate or on the ammonia excretion rate. For other octopod species, the dependence of metabolic rate on temperature does not differ with that for O. vulgaris.