453
24 Octopus vulgaris: Ongrowing
rainfall, whilst in tanks Delgado et al. (2011) found no significant differences in
growth or survival in the salinity range of 29–34 psu.
24.2.2 Temperature
Aguado-Giménez and García García (2002) developed models of growth and
feeding rates as a function of BW (0.18–3.50 kg), temperature (13–28 °C) and
feed type (bogue Boops boops and crab Carcinus maenas) based on 236 observations made in tanks containing isolated animals. Maximum growth was obtained
at 17.5 °C, falling as the temperature rose to reach negative values at 28 °C. The
maximum feeding rate was obtained at 20 °C and as a consequence of these two
findings, the maximum feed efficiency would be around 16.5 °C. Mortality rose
sharply above 22 °C, so that the authors established that the optimal range for octopus ongrowing is between 16 and 22 °C. Subsequently, Miliou et al. (2005), who
obtained similar results, identified a significant interaction between weight and
temperature, probably because they used smaller specimens than did the above
authors. This interaction meant that the temperature at which maximum growth
was achieved varied with the weight; this temperature for weights of 50–150 g
was 25 °C.
24.2.3 Dissolved Oxygen
Cerezo Valverde and García García (2005) studied the octopus respiratory behaviour in relation to decreasing saturation level, measuring oxygen consumption and
ventilation frequency for a wide range of BWs and temperatures, establishing three
oxygen concentrations: optimal, suboptimal and dangerous. In the optimal range,
neither oxygen consumption nor ventilation frequency varied, while in the suboptimal range ventilation frequency was modified and in the dangerous range both
parameters were modified. These ranges were temperature dependent: At 16 °C, the
minimum saturation level in the optimal range was 55 %, while at 25 °C it was 85 %.
The lethal oxygen concentration was found to be below 15 % and directly dependent on both BW and temperature, varying from 3 % saturation (15 °C and 0.2 kg)
to 9 % (27 °C and 2 kg).
24.2.4 Nitrogenated Compounds
Little attention has been paid to the effect of nitrogenated compounds (ammonia/
ammonium, nitrates and nitrites) in cephalopods so that the maximum levels
assumed are those that have been established in a general way for fish (Tucker 1998).
24 Octopus vulgaris: Ongrowing
rainfall, whilst in tanks Delgado et al. (2011) found no significant differences in
growth or survival in the salinity range of 29–34 psu.
24.2.2 Temperature
Aguado-Giménez and García García (2002) developed models of growth and
feeding rates as a function of BW (0.18–3.50 kg), temperature (13–28 °C) and
feed type (bogue Boops boops and crab Carcinus maenas) based on 236 observations made in tanks containing isolated animals. Maximum growth was obtained
at 17.5 °C, falling as the temperature rose to reach negative values at 28 °C. The
maximum feeding rate was obtained at 20 °C and as a consequence of these two
findings, the maximum feed efficiency would be around 16.5 °C. Mortality rose
sharply above 22 °C, so that the authors established that the optimal range for octopus ongrowing is between 16 and 22 °C. Subsequently, Miliou et al. (2005), who
obtained similar results, identified a significant interaction between weight and
temperature, probably because they used smaller specimens than did the above
authors. This interaction meant that the temperature at which maximum growth
was achieved varied with the weight; this temperature for weights of 50–150 g
was 25 °C.
24.2.3 Dissolved Oxygen
Cerezo Valverde and García García (2005) studied the octopus respiratory behaviour in relation to decreasing saturation level, measuring oxygen consumption and
ventilation frequency for a wide range of BWs and temperatures, establishing three
oxygen concentrations: optimal, suboptimal and dangerous. In the optimal range,
neither oxygen consumption nor ventilation frequency varied, while in the suboptimal range ventilation frequency was modified and in the dangerous range both
parameters were modified. These ranges were temperature dependent: At 16 °C, the
minimum saturation level in the optimal range was 55 %, while at 25 °C it was 85 %.
The lethal oxygen concentration was found to be below 15 % and directly dependent on both BW and temperature, varying from 3 % saturation (15 °C and 0.2 kg)
to 9 % (27 °C and 2 kg).
24.2.4 Nitrogenated Compounds
Little attention has been paid to the effect of nitrogenated compounds (ammonia/
ammonium, nitrates and nitrites) in cephalopods so that the maximum levels
assumed are those that have been established in a general way for fish (Tucker 1998).