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The aim of this study was to test the effect of copper supplementation in a formulated feed on the growth, feed efficiency, and nutritional composition of subadults Octopus vulgaris, with particular reference to the differences in the content of copper in the tissues (muscle, digestive gland, and hemolymph). Two formulated feeds were supplied to subadults octopuses kept individually for 56 days: Basal diet [11.6 mgCu/kg dry weight (dw)], and another feed with a similar composition but including a copper supplementation (copper diet: 115.2 mgCu/kg dw). No significant differences (P > 0.05) were detected in the respective growth rates (0.88% body weight/day), FE (79.5%–82.1%), proximate composition, hemolymph hemocyanin (1.6–1.8 mmol/L), hemolymph copper (0.19–0.20 mgCu/mL), or muscle copper levels (22.7–23.2 mgCu/kg dw). No significant changes were detected on proximate composition, hemocyanin and hemolymph, and muscle copper levels between animals fed formulated feeds and an initial group fed nat...

The development of artificial diets is considered vital for feasible cephalopods&rsquo, culture. Octopus vulgaris need a diet with a high protein content but also lipids are important at a lower quantity, as polar lipids and LC-PUFA are essential for development during early stages. In the present study the suitability of marine lecithin as a dietary supplement for O. vulgaris juveniles&rsquo, formulated feeds was tested for 56 days, assessing the performance, changes in proximate composition, and lipid classes&rsquo, profile in the digestive gland and carcass. Sixteen octopus were fed one of two semi-moist feeds based on dry ingredients: either CALPRO (N = 4) as control or CALPRO-LM (N = 8), which differed from the first, due to the inclusion of 20 g/kg of marine lecithin as a phospholipid dietary supplement. Results showed that marine lecithin did not enhance feed intake, growth, protein or lipid incorporation, nutrients digestibility or feed efficiency. Moreover, at this level of inclusion, the composition of tissues (digestive gland and carcass) regarding macronutrients and lipid classes&rsquo, profile presented only a small amount of differences. In conclusion, the inclusion of marine lecithin did not promote beneficial effects on performance, making necessary further research related to the nutritional requirements of common octopus.

Growth, feed efficiency and proximate and lipid class composition of subadults Octopus vulgaris (788 ± 133 g; 18.5°C) fed formulated diets of low lipid (LL: 8 g kg−1) and high lipid levels (HL: 84 g kg−1) and each one of these with three different levels of glutamate supplementation (0, 5 and 20 g kg−1) were compared. All the animals accepted the diets with a survival of 100%. The addition of glutamate did not stimulate feeding rates in any of the assays (2.48–2.64 and 1.86–2.01%Body weight day−1 for LL and HL, respectively; P > 0.05). The best growth, feed efficiency and protein productive value were observed in the groups fed 5 or 20 g kg−1 glutamate supplementation at both lipid levels, with significant differences for LL diet (P

Spider crab, Maja brachydactyla, is a crustacean with interesting biological characteristics for intensive aquaculture. However, physiological studies are needed to establish the optimal conditions for its culture and maintenance. We analyzed the oxygen consumption response of spider crab to gradual hypoxia in relation to animal weight (W: 0.42–1.62 kg) and water temperature (T: 17.8–26.3 C), along with its ability to recover. Spider crab behaved as an oxygen regulator, maintaining its oxygen consumption constant until it reached critical oxygen saturation. This value varied between 24.1 and 53.3% oxygen saturation (42.4 ± 7.4% Sat.; 2.95 ± 0.43 mgO2/L), and significantly depended on the temperature (P < 0.01). The lethal oxygen saturation varied from 6.8 to 19.3% Sat. (12.57 ± 4.25% Sat.; 0.88 ± 0.29 mgO2/L) depending on temperature and body weight (P < 0.05). When oxygen levels were re-established after exposure to acute hypoxia, the animals recovered, oxygen consumption remaining above the routine value for up to 15–20 h. We suggest survival oxygen saturation levels for spider crab of between 100 and 65% in the experimental conditions of this study.

In this work, we study the variations in concentration (mg 100 g−1 dry weight) and total content (mg individual−1) of different lipid classes in muscle and the digestive gland of Octopus vulgaris during an 8-day starvation period. In all the samples analysed, polar lipids (PL) predominated in muscle (267.3–337.2 mg 100 g−1) compared with neutral lipids (66.9–104.7 mg 100 g−1). A significant positive tendency was observed in muscle for the content and concentration of monoglycerides as a consequence of starvation (P

The rate of total ammonia excretion ( U , mg TAN d − 1 ) in relation to body weight ( W , 490–3460 g) and absolute protein feeding rate (APFR, 0.00–11.90 g d − 1 ) was studied in octopus ( Octopus vulgaris ). Using multiple regression analysis, the data obtained were fitted to the equation U = 13.91 + 0.07 W + 0.02 W × APFR, which explained 95% of the variance observed. According to this equation, there was a significant interaction between W and APFR ( W × APFR), the coefficient of W varying linearly with APFR ( b ' = 0.07 + 0.02APFR). When U was expressed as a function of body weight (Ur, mg TAN kg − 1 body weight d − 1 ), Ur basically varied as function of APFR, showing a value of 84 mg TAN kg − 1 body weight d − 1 when the octopus was not fed and 265 mg TAN kg − 1 body weight d − 1 when protein intake was 9 g d − 1 . U increases linearly with body weight from 10 to 57 g TAN kg − 1 feed dry matter d − 1 when APFR is 9 g d − 1 .

Sediment cores were taken from impacted and non-impacted areas and subjected to different incubations: (i) uninoculated, (ii) inoculated with fish feed and (iii) inoculated with gilthead seabream (Sparus aurata) faeces. After inoculation (or not), the cores were incubated for 8 h and the following biogeochemical fluxes were determined: sediment oxygen uptake (SOU), total ammonia nitrogen flux (TANf) and the production of acid volatile sulphides (AVS-Sp). The results showed that the impacted sediments had a more pronounced benthic metabolism than non-impacted sediments. Correlations between the variables and factorial analysis showed that oxygen consumption caused by the organic enrichment appeared as the trigger for subsequent biogeochemical alterations. The addition of faeces led to proportionally higher benthic rates of SOU, TANf and AVS-Sp than those obtained in the feed incubations. Although the feed is relatively sterile and does not create an oxygen demand until colonized by bacteria, the faeces are already richly colonized with fish gut bacteria and could start to consume oxygen without the lag phase experienced in the incubations with feed. The TANf values measured after the addition of feed or faeces seem to be more related to the leaching velocity of TAN than with the benthic flux, given the short incubation time.

Spider crab ( Maja brachydactyla ) is considered a species of potential interest for intensive aquaculture, although physiological studies are necessary before the optimal conditions for its culture can be established. In this paper we develop equations to explain the oxygen consumption of the species as a function of weight ( W : 15–1414 g), temperature ( T : 13.5–27.9 °C), sex ( S ) and daily light–dark cycle (14L/10D to 10L/14D). The measurements were carried out over three days on single animals receiving one meal of mussels to satiation only on the first day of the measurements. The oxygen consumption values were divided into routine (MO 2routine ), post-prandial (MO 2sda ), maximum peak (MO 2peak ) and daily average between 0–24 h (MO 2; 0–24 h ), 24–48 h (MO 2;24–48 h ) and 48–72 h (MO 2;48–72 h ) post-feeding. Feeding led to an increase in oxygen consumption 1.7–7.3 (2.90 ± 1.25) times the routine value, with maximum peaks between 2 and 16 h post-feeding (7.94 ± 4.12 h) the effect lasting 10–24 h (19.80 ± 3.56 h). The different levels of oxygen consumption were expressed as lnMO 2routine = 0.206 + 0.837ln W + 0.302 T − 0.006 T 2 − 0.153S, lnMO 2sda = 0.294 + 0.736ln W + 1.372ln T − 0.171S, lnMO 2peak = 3.032 + 0.667ln W + 0.083 T − 0.158 S and lnMO 2; 0–24 h = 0.403 + 0.769ln W + 1.305ln T − 0.147 S , all to a statistically significant degree ( P

This study established different oxygen level categories (optimal, sub-optimal, dangerous and lethal) for Dentex dentex according to ventilatory frequency ( V f ) and oxygen consumption ( M O 2 ) in response to gradually decreasing dissolved oxygen levels for different fish masses (117–745 g) and water temperatures (13.9–28.1 °C). Initial and maximum ventilatory frequency ( V f0 and V fmax , respectively) and oxygen saturation at which ventilatory frequency was altered ( S Vf ) ranged from 31.3 to 71.3 beats/min, 58.0 to 129.7 beats/min and 48.1 to 81.7%, respectively. D. dentex maintained a constant M O 2 rate, until a critical oxygen saturation ( S crit ) was reached. The S crit and lethal oxygen saturation (LS50) ranged from 26.5 to 40.6% and 12.3 to 18.9%, respectively. V f0 , V fmax , S crit and LS50 were correlated positively and significantly with temperature, but only V fmax was correlated with body mass, pointing to a higher V f response in small than large fish. In the range of fish masses and temperatures tested, our findings suggest an optimal dissolved oxygen saturation of above 70–75% (constant V f and M O 2 ), a sub-optimal value of between 70 and 35% (altered V f but not M O 2 ), with anything below 35% being dangerous (altered V f and M O 2 ). We conclude that suitable oxygen levels for D. dentex are similar with respect to other species of interest in aquaculture.

The dissolved oxygen level is an essential parameter for defining water quality in aquaculture. However, the optimal values of this gas can vary greatly depending on the species, body weight, or water temperature. In this study, different oxygen level categories (optimal, suboptimal, dangerous, and lethal) were established for Octopus vulgaris (0.18–2.20 kg; 15.5–27.4 °C) according to ventilatory frequency (Vf) and oxygen consumption (MO2) in response to gradually decreasing dissolved oxygen levels. Initial and maximum ventilatory frequency (Vf0 and Vfmax, respectively) and oxygen saturation at which ventilatory frequency is altered (SVf) showed mean values of 17.7±3.29 bts/min, 33.3±5.86 bts/min, and 62.8±15.94% (4.5±0.95 mgO2/l), respectively, and all variables were positively correlated with temperature (P

Feeding periods are accompanied by increased oxygen demand, and so, water flow or oxygen supply during culture should be suitably adjusted at such times. In this study, we determine the pattern of post-prandial oxygen consumption in common octopus ( Octopus vulgaris ) with body weights between 0.22 and 3.26 kg, at temperatures of 13.75–22.23 °C, which covers the normal ranges of weight and temperature used for its culture. The measurements were carried out over 3 days on single animals receiving one meal of crab to satiation. The oxygen consumption values were divided into routine ( M O 2routine ), post-prandial ( M O 2sda ), maximum peak ( M O 2peak ) and daily average between 0 and 24 h ( M O 2;0–24h ), 24 and 48 h ( M O 2;24–48h ) and 48 and 72 h ( M O 2;48–72h ) post-feeding. Furthermore, the time taken to reach M O 2 peak ( D peak ) and the duration of post-prandial oxygen consumption ( D sda ) were calculated. In all cases, M O 2;0–24h was higher than M O 2;24–48h and M O 2;48–72h ( P M O 2;24–48h and M O 2;48–72h ( P >0.05). This result suggests that feeding induces a significant transient short-term effect on oxygen consumption that does not usually last longer than 24 h. The different oxygen consumption categories fitted the equations ln M O 2routine =−0.726+0.702ln W +1.876ln T , ln M O 2sda =0.045+0.713ln W +1.769ln T , ln M O 2peak =0.152+0.716ln W +1.767ln T and ln M O 2;0–24h =0.220+0.716ln P +1.688ln T to a statistically significant degree ( P D peak and D sda showed values of 6–16 h (9.98±2.49 h) and 15–28 h (19.79±3.83 h), respectively, both being independent of weight and temperature ( P >0.05). Finally, the influence of other factors such as daily activity patterns or sex on oxygen consumption were analysed.

The amino acid composition and protein levels of three species of cephalopods (Octopus vulgaris, Loligo gahi and Todarodes sagittatus), the natural diets of common octopus (O. vulgaris) and different kinds of meals were determined in order to optimise the content of these nutrients in artificial feeds. Arginine, leucine and lysine were the most abundant essential amino acids in cephalopods, while glutamate and aspartate represented the main non-essential amino acids. Arginine and leucine were the limiting amino acid in most samples, with maximum Chemical Score values for mussel (79-98 %), squid (84 %) and crustaceans (65-91 %); medium for fish (41-70 %); and minimum for meals (29-64 %). Mussel, squid, crustaceans and fish showed a high essential amino acid index according to Oser (OI: 88-99 %) suggesting a suitable amino acid balance. The protein from animal meals (fish and krill) covered all the essential amino acids except arginine and lysine in fish meal. The vegetable meal presented the worst amino acid balance (OI: 74-89 %) with several deficiencies in essential amino acids, including arginine, threonine, lysine and methionine. Supplementation with arginine or leucine and protein complementation of crustaceans and bivalves with fish or animal meal are proposed as alternatives for improving the performance of protein in feed for cephalopods. © 2012 Springer Science+Business Media B.V., Project financed by the National Marine Culture Plans of JACUMAR.