Effect of glycerol on the lipids in the red alga Gratelupia doryphora

Se cultivó alga roja Gratelupia doryphora en agua de mar enriquecida con Provasoli y en glicerol. La incubación en agua de mar condujo a un aumento en el porcentaje de los ácidos grasos polünsaturados, mientras que el glicerol incrementó el contenido de lípidos totales. Por tanto, si la alga está siendo producida como un cultivo heterotrófico, es posible aumentar la biomasa de la misma así como el contenido de ácidos grasos biológicamente activos. The red alga Gratelupia doryphora was cultivated in Provasoli enricher (plain) seawater and in a glycerol media. The incubation in seawater leads to an increase in the percentage of polyunsaturated acids, while the glycerol increase the total lipid content. If the alga is being grown as a heterotrophic culture, it is possible to increase the alga biomass as well as the content of biologically-active fatty acids.

Effect of sex ratio on growth and survival in Octopus vulgaris (Cuvier, 1797) reared in floating cages

[EN]Octopus vulgaris is a potential candidate to diversify European aquaculture for its rapid growth and high market prices (Vaz Pires et al. 2004). One factor affecting industrial development of octopus culture is sexual maturation under rearing conditions. Octopus females can lose up to 30-60% of their initial body weight during egg-laying (Iglesias et al., 2000) and die after the paralarvae hatch (Guerra,1992), while a correlation between males death and spermatic sac depletion has being recently reported by Estefanell et al. (2010b). The present experiment discusses the effect of three different sex ratios on growth, sexual maturation and survival in O. Vulgaris. Conclusions: Discarded bogue from fish farms could be used as alternative diet for the final stage of O. vulgaris ongrowing ; Male segregation would maximize biomass increment ; Under the conditions described, sex ratios close to 1:1 produced higher biomass increment than 4:1

Efecto de la inclusión de harinas de cangrejo de diferente origen en piensos para bocinegro (Pagrus pagrus) sobre la textura, oxidación y composición del filete

[EN]The inclusion of two different crab meals in diets on fillet quality parameters was investigated in a six month growth trial with red porgy (Pagus pagrus). A high quality fish meal and fish oil diet was used as a control (Diet C). Fish meal protein in the control diet was replaced by increasing levels of protein from a river crab meal (Procamburus clarkii) (CR) and a marine crab meal (Chaceon affinis) (CM) at 10% and 20% each of them. The inclusion of both crab meals in diets, either at 10% and 20% substitution levels, did not affect the texture quality parameters of flesh except for the adhesiveness, where animal fed on CR20 showed the smallest value respect to those fed the Diet C. Compared to the control fish, a reduction of the fillet lipid oxidation indicated by the Tbars index was observed for fish fed both crab meal based diets, at the higher inclusion level (20%). Increasing dietary levels of the marine crab meal showed an increment of the monoenoicos, n-9 and oleic fatty acid content in the fillets. Results indicate that both crab meals used in present study are suitable as alternative ingredients for red porgy diets in terms of fish flesh quality.

Evaluación de 2 sistemas de cultivo en pulpo común Octopus vulgaris en jaulas en la comunidad Canaria

Octopus vulgaris on-growing in floating cages is a promising activity implemented in Spain at industrial level, with productions of 16-32 tons/year from 1998. Nevertheless, some aspects of the culture system need to be evaluated to warrantee its profitability. In the present study two rearing systems and two dietary treatments were evaluated. Individual and group rearing, in PVC net compartments and floating cages respectively, were compared under two dietary treatments. One diet was composed by bogue, supplied as ?discarded? species from local fish farms, and the other was based on a 40-60% discarded bogue-crab Portunus pelagicus. All octopuses were PIT-tagged and the experiment lasted two months. Animals were sampled once throughout the experimental period and absolute growth rate (AGR, g./day) and mortality (%) were calculated. AGR of group rearing was above 30 g./day, however individual rearing showed 100% survival so biomass increment was higher. On the other hand, males grew more than females regardless of dietary treatment.

Efecto de la inclusión de harinas de cangrejo de diferente origen en piensos para bocinegro (Pagrus pagrus) sobre el crecimiento, utilización de la dieta y coloración de la piel

[EN] The effect of dietary inclusion of two type of crab meal on growth, feed utilization and skin coloration performance was investigated in a growth trial with red porgy (Pagrus pagrus) of 233g initial body weight, during 6 month feeding period. High quality fish meal and fish oil diet was used as a control (Diet C). Protein of fish meal in the control was replaced by increasing dietary levels of protein derived from a river crab meal (Procamburus clarkii) (CR) and a marine crab meal (Chaceon affinis) (CM) at 10% and 20% each of them. Regarding growth results, fish fed the CM20 diet showed the highest values in absolute final weight and percent of the initial weight. For animals fed the crab meal based diets, the colour result was better than that of fish fed the control one, showing skin redness similar to that of the wild specimens. For both ingredients, increasing dietary inclusions were accompanied for an increment of the colour saturation, being in this case the obtained value for the CR meal higher than those for the CM meal. Present results indicate that crab meals used in this study are suitable as partial replacers for fish meal in diets for the red porgy.

Muscular development and physical activity as major determinants of femoral bone mass acquisition during growth

[EN] OBJECTIVES: To investigate to what extent bone mass accrual is determined by physical activity and changes in lean, fat, and total body mass during growth. METHODS: Twenty six physically active and 16 age matched control boys were followed up for three years. All subjects were prepubertal at the start of the survey (mean (SEM) age 9.4 (0.3) years). The weekly physical activity of the active boys included compulsory physical education sessions (80-90 minutes a week), three hours a week of extracurricular sports participation, and occasional sports competitions at weekends. The physical activity of the control group was limited to the compulsory physical education curriculum. Bone mineral content (BMC) and areal density (BMD), lean mass, and fat mass were measured by dual energy x ray absorptiometry. RESULTS: The effect of sports participation on femoral bone mass accrual was remarkable. Femoral BMC and BMD increased twice as much in the active group as in the controls over the three year period (p < 0.05). The greatest correlation was found between the increment in femoral bone mass and the increment in lean mass (BMC r = 0.67 and BMD r = 0.69, both p < 0.001). Multiple regression analysis revealed enhancement in lean mass as the best predictor of the increment in femoral bone BMC (R = 0.65) and BMD (R = 0.69). CONCLUSIONS: Long term sports participation during early adolescence results in greater accrual of bone mass. Enhancement of lean mass seems to be the best predictor of this bone mass accumulation. However, for a given muscle mass, a greater level of physical activity is associated with greater bone mass and density in peripubertal boys.

Horn-schunck optical flow with a multi-scale strategy

[EN] The seminal work of Horn and Schunck [8] is the first variational method for optical flow estimation. It introduced a novel framework where the optical flow is computed as the solution of a minimization problem. From the assumption that pixel intensities do not change over time, the optical flow constraint equation is derived. This equation relates the optical flow with the derivatives of the image. There are infinitely many vector fields that satisfy the optical flow constraint, thus the problem is ill-posed. To overcome this problem, Horn and Schunck introduced an additional regularity condition that restricts the possible solutions. Their method minimizes both the optical flow constraint and the magnitude of the variations of the flow field, producing smooth vector fields. One of the limitations of this method is that, typically, it can only estimate small motions. In the presence of large displacements, this method fails when the gradient of the image is not smooth enough. In this work, we describe an implementation of the original Horn and Schunck method and also introduce a multi-scale strategy in order to deal with larger displacements. For this multi-scale strategy, we create a pyramidal structure of downsampled images and change the optical flow constraint equation with a nonlinear formulation. In order to tackle this nonlinear formula, we linearize it and solve the method iteratively in each scale. In this sense, there are two common approaches: one that computes the motion increment in the iterations, like in ; or the one we follow, that computes the full flow during the iterations, like in. The solutions are incrementally refined ower the scales. This pyramidal structure is a standard tool in many optical flow methods.

Diferencias en el comportamiento de los peces ante buceadores en apnea o con equipo autónomo de respiración

[ES] Se observa que la mera presencia de buceadores con equipo autónomo de respiración tiene un efecto de atracción sobre los peces, increment&aacute;ndose en el área de actividad del buceador a medida que se prolonga el tiempo de la inmersión. Sin embargo, si la actividad de buceo se hace en apnea, el efecto sobre la abundancia de peces en el área es el contrario.

Comportamiento de "Osilinus atratus" (Wood, 1828) ante diferentes sustratos rocosos

[ES] Se estudia el comportamiento del burgado (Osilinus atratus) ante diferentes tipos de sustratos rocosos, tanto en color como en tamaño. Los individuos muestran cierta tendencia a permanecer sobre sustratos de color gris-verdoso, sobre piedras de basalto-fonolitas, muy similares a los colores que abundan en las conchas de esta especie. Igualmente, evitan permanecer sobre sedimentos de pequeña granulometría, increment&aacute;ndose el tiempo de permanencia cuanto mayor es el grano del sedimento.