Applied Ecophysiology: An Integrative Form to Know How Culture Environment Modulates the Performance of Aquatic Species from an Energetic Point of View - Aquaculture and the Environment: A Shared Destiny - page 167

in high quantities that could be demanded to produce biomass could be a limit for the
growth abalone culture.
3.3 The case of cephalopods Octopus maya , Enteroctopus megalocyathus and O.
vulgaris
Of cephalopods, octopuses are considered economically interesting species for aquaculture.
Landings in this area have been steadily decreasing since the 90's, which has led to increase
the demand for octopuses and thus the technological-scientific efforts to rear them. Rearing
is defined as the development of juveniles from an egg or paralarva with the ability to reach
a second stage (Boletzky, 2003). Many cephalopods have been subject of several studies in
captivity intended to investigate behavioural aspects (Hanlon & Wolterding, 1989; Hochner
et al., 2006), used as models in neurophysiology studies (Flores, 1983; Wollesen et al., 2009),
in predator-prey relationships (Villanueva, 1993; Scheel, 2002; Smith, 2003) or to provide live
specimens for aquariums (Summer & McMahon, 1970; Bradley, 1974; Anderson & Wood,
2001). In the last years, many studies related with octopus and sepia culture have been
putting in evidence the increased interest in their culture (for reviews see) (Sykes et al., 2006;
Iglesias et al., 2007; Uriarte et al., 2011). Octopus are semelparous, that means that females
spawn once in their life and die soon after the eggs hatch (Hanlon et al., 1991).The life span
of the most of cephalopods species is short varying from about 6 months in small species to
between one to three years in larger ones (Villanueva & Norman, 2008). Recent works show
the very fast and high rates of food consumption, food conversion and growth of octopus.
Most of our knowledge of octopus energy budget comes from studies of few species
potentially due to their fisheries value and their potential as culture species.
Octopus vulgaris is by far the most studied between octopus species. At the date there are
many investigations related with some aspects of energy budget. To exemplify the use of
ecophysiological studies on octopus culture there are several studies in which octopuses
were fed squid and tested at different experimental temperatures (Katsanevakis et al . , 2005;
Miliou et al . , 2005). Katsanevakis et al. (2005) tested the effects of temperature and body
weight on respiratory metabolism of juveniles of O. vulgaris. Using data obtained on that
study a surface plot was constructed using a quadratic model for routine metabolism
(Rrout) expressed as joules per day (Fig. 3).
That model was constructed using an interval of octopus living weight between 0.1 to 1kg and
a sea water temperature between 13 to 28°C. With this information we can now calculate how
much energy will be metabolized if octopuses of 0.1kg are cultivated at 15°C and in
consequence how much food should be used to cover that energetic demand: Using the model:
Rrout = 19403.7-[15.3 (0.1kg)] - [2040.6(15°C)] - [0.003 (0.1kg) 2 ] + [2.4 (0.1kg x 15°C)]
+ [52.2 (15°C) 2 ] = 541.2 joules day -1
To validate that model, we re-calculated the Rrout value obtained with last equation but
using the living weight of octopuses used in other studies where Rrout was also measured.
To do that we used weight values from García-Garrido et al. (2011) how made respirometric
measurements of O. vulgaris (850g) fed squid at 15°C. The Rrout found by authors in that
study was 671 joules day -1 , close to that obtained if the quadratic model is applied (554.4
joules day -1 ). That concordance suggests that the quadratic model calculated now gave
comparable data with other experimentally obtained (García-Garrido et al . , 2011).