Efecto de los misidáceos en la calidad de la puesta en el caballito de mar, Hippocampus hippocampus (Linnaeus, 1758)

[EN]The importance of a suitable feeding in reproduction and spawning quality of teleost fish has been recognized as one of the major ?bottlenecks? in new aquaculture species like seahorses. Mysidacea species has been described as one of the main food for temperate seahorse species (Hippocampus hippocampus and H. guttulatus) in the wild. On the other hand, Artemia has been employed usually as marine food for rearing fish, including seahorses. The aim of this work is to study the effect of two different live preys (Artemia vs Mysis) in spawning quality of H. hippocampus broodstock. The animals were fed two times per day, six times per week. Spawning episodes and larvae quality was recorded. Seahorse fed on mysis showed significantly better results (p<0.05) than Artemia treatment, regarding spawning events, number of offspring?s and size. This fact showed the high potential of mysis as live prey for seahorses or other ornamental species.

Efecto de la primera alimentación en la supervivencia y el crecimiento de crías de caballito de mar, Hippocampus hippocampus (Linnaeus, 1758)

[EN]Effects of first feeding on survival and growth of Atlantic seahorse juveniles, Hippocampus hippocampus, (Linnaeus, 1758). In this study, two experimental protocols were tested: a first treatment (RA), in which larvae were fed exclusively on rotifers until day 5, and then on Artemia, and a second treatment (A) where larvae were only fed on Artemia. We attempted to improve survival and growth by comparing different diets in the first days of life. The results showed excellent survival (60% average) and growth in juveniles exclusively fed with Artemia, with better values than those obtained by other authors for this species. In comparison, high mortality and poor growth were observed on the first days in larvae fed rotifers.

Efecto de la densidad larvaria y secuencial alimentaria en el cultivo larvario de corvina (Argyrosomus regius Asso, 1801) durante el primer mes de vida

Effect of larval density and feeding sequence on meagre (Argyrosomus regius Asso, 1801) larval rearing during the first month of life. In the present work two comparative studies of the effect of larval density and feeding sequence were performed. For such, two initial larval densities, 50 larvae.l-1 and 100 larvae.l-1 were established. In each density three feeding sequences were tested, applying different combinations of rotifers (Brachionus sp.) and Artemia sp. at different larval ages. After 30dah, standard length, dry weight and final survival were determined. Final survival was affected by initial larval density and feeding sequence. Lower density promotes better growth in dry weight and standard length for all the feeding sequences tested. In addition, feeding sequences affects larval growth and survival. Best result in survival (62,81±4,77%) were obtained with high larval density and T2 feeding sequence.

Optimización del protocolo de destete de corvina (Argyrosomus regius, Asso, 1801)

[EN] Argyrosomus regius is a new species of interest in aquaculture. Nevertheless, few are the works published on this species and less even in larvae culture and weaning. In this study 2 experiments were done, in tanks of 15 l, with larvae of 15 and 34 days of life, respectively to which 2 different protocols for their weaning were applied. The provided food consisted of a mixture of Artemia and microdiet to different concentration. In experiment A, the best results of growth were observed in treatment 1 and worse in treatment 3, nevertheless in the survival the opposite happened. In experiment B, the best results they were reached with larvae submitted to low density and with significant difference between treatment 1 and 2, in survival no significant differences were found between the different treatments.

Experiencias preliminares de cultivo de crías de Hippocampus hippocampus (Linnaeus, 1758) en Gran Canaria

[EN]Seahorses husbandry constitute an innovative aspect on the recovery of wild populations. In this study, two aeration levels were tested (normal and strong) in seahorse juveniles fed on Artemia. Survival and growth were evaluated. The results showed higher survivals (11% average) with strong aerations levels after 90 days. In addition, these juveniles were able to reproduce after 4 months, denoting the early sexual maturation of this species. However, sizes of second-generation larvae at day 0 were smaller compared with those produced by their parents

Avances en ecofisiología planctónica y oceanografía bioquímica en la ULPGC

[EN] This seminar will report the latest activities of the ULPGC»s Plankton Ecophysiology group (PEG). This group studies respiration, growth, nitrogen metabolism, oceanic carbon flux, deep ocean metabolism, and plankton cultivation. It works with zooplankton, phytoplankton, bacteria, and macroalgae. The premise behind the group»s investigations is that enzyme biochemistry controls an organism»s physiology that, in turn, has a strong impact on ocean chemistry and ecology. This research team (PEG) uses as foils, the metabolic theory of ecology (MTE) and Kleiber»s law to argue the fact that respiratory metabolism is controlled not by biomass, but by the respiratory electron transport system (R-ETS). It has pointed out that the reason, zooplankton respiration statistically correlates with biomass, is because biomass packages mitochondria and mitochondria package the R-ETS. It has demonstrated, experimentally with Artemia salina, the superiority of using ETS as a respiration proxy rather than using biomass. Working with bacteria it has shown the inadequacy of the MTE in describing respiration in different growth phases of bacteria and has shown that a rival model based on enzyme kinetics works much better.

Importance of dietary n-3 hufa for eye development and cone formation along gilthead seabream sparus aurata larval development.

[EN] Being fish larvae visual feeders, vision plays an important role in larval orientation at first feeding (Blaxter, 1986). Larval trophic behaviour is closely related with the development of the visual capacity, which directly depends on retina organogenesis. In sparids, such as Pagrus major (Kawamura, 1984) and Pagrus auratus (Pankhurst, 1996), the most important changes in the eye structure occur along the lecitotrophic stage as a preparation for prey capture. Neuringer et al.,(1988) has established a critical role for n-3 polyunsaturated fatty acids and, particularly docosahexaenoic acid (DHA) in neural and retinal tissue functions in mammals. Similarly, in larval fish there is a high demand of DHA to form nervous membranes. Bell and Dick (1993) found photoreceptors in the eye, rods and cones accumulate and selectively retain DHA in external segments.Bell et al. (1995) found that feeding juvenile herring a DHA poor Artemia diet during the period of rod development resulted in impaired vision at low light intensities, when rod vision is essential.

Effect of different live prey, Grapsus grapsus Linnaeus 1758 and Plagusia depressa Fabricius, 1775 zoeas,over histology and biochemical composition of common octopus, octopus vulgaris Cuvier, 1797 paralarvae

[EN] Since paralarval rearing is still the main bottleneck for the development of octopus culture, the aim of the present study was to obtain some information on the feeding strategy and nutritional requirements during paralarval stage. For that purpose just hatched out octopus paralarvae were fed with live preys in three different combinations, trying to match their natural food: Enriched Artemia metanauplii, Grapsus grapsus zoeas supplemented with enriched Artemia, and Plagusia depressa zoeas supplemented with enriched Artemia. Paralarval treatments were carried out during 28 days in triplicates; fibre glass 120 l tanks in flow through system were used. Growth, in terms of dry body weight, mantle length and width, was determined each seven days. A histological study of the paralarval development was carried out. Biochemical composition of preys and paralarvae were determined. Growth was significantly better in paralarvae fed with zoeas and Artemia than in those fed only with Artemia, from day 8 after hatching. Besides a clear effect on the digestive gland histology morphology was observed.

Effect of culture system and diet in early larval stages over skeletal deformities development in gilthead sea bream

[ES] Main deformities such as lordosis, opercular deformities and upper/lower jaws shortening are considered as quality descriptors in commercial marine fish fry production and seem to be related with larval culture conditions in early larval stages. The aim of this work was to obtain information about the contribution of the diet and rearing system to the apparition of these abnormalities in gilthead sea bream (Sparus aurata) larvae in semi-industrial scale facilities. For that purpose, two different larval rearing systems semi-intensive and intensive were compared; besides, two different rotifer enrichments, DHA Protein Selco, (Inve Aquaculture, Dendermonde, Belgium) (R1) and Red Pepper Paste, (Bernaqua bvba, Turnhout, Belgium) were tested in the intensive system. Biochemical composition of larvae, preys and commercial products was analysed. At 50 days post hatching six hundred fish per treatment were individually studied under stereoscope and deformity frequency recorded. Besides at 95 days post hatching fry were soft X ray monitored. Both rotifer enrichment and rearing system affected survival, growth and deformity frequency. Rearing system did not affect total larvae fatty acid content except at 20 dah, where DHA were significantly higher and EPA significantly lower in Semi-intensive system. A significantly lower percentage of deformity rates together with better survival and growth were obtained in the semi-intensive system. In dietary treatment, rotifer enrichment significantly affected larval survival. R1 rotifers enrichment significantly (P<0.05) improved survival when compared to fed R2 larvae. The content of DPA was significantly (P<0.05) higher in R2 fed larvae reflecting the R2 rotifers content of this fatty acid. The level of this FA tended to decrease in concordance with the rotifers replacement by artemia in the diet. The effects n-3-HUFA and DPA (22:5n-6) over larval survival and skeletal deformities development is discussed.

Crecimiento y supervivencia de paralarvas de O. vulgaris cultivadas bajo diferentes intensidades de luz.

[EN] Paralarval rearing constitutes the main bottleneck to the complete development of octopus culture. This paper try to optimise the larval rearing conditions of Octopus Paralarvae, testing the effect of light intensity (1000, 3000 and 6000 lux ) over growth and paralarval survival. Four fibber glass tanks, 100 litter capacity with an initial density of 20 ind./litter were used for each treatment. All light treatments were fed with the same protocol, just hatching Maja Squinado Zoeas and Artemia metanaulios (72 hours)enriched with a commercial emulsion (Red Pepper Paste, Bernaqua, bva; Belgium). Better growth and survival were found with the highest light intensity treatment.

Gender-specific modulation of immune system complement gene expression in marine medaka Oryzias melastigma following dietary exposure of BDE-47

BDE-47 is one of the most widely found congeners of PBDEs in marine environments. The potential immunomodulatory effects of BDE-47 on fish complement system were studied using the marine medaka Oryzias melastigma as a model fish. Three-month-old O. melastigma were subjected to short-term (5 days) and long-term (21 days) exposure to two concentrations of BDE-47 (low dose at 290 +/- 172 ng/day; high dose at 580 +/- 344 ng/day) via dietary uptake of BDE-47 encapsulated in Artemia nauplii. Body burdens of BDE-47 and other metabolic products were analyzed in the exposed and control fish. Only a small amount of debrominated product, BDE-28, was detected, while other metabolic products were all under detection limit. Transcriptional expression of six major complement system genes involved in complement activation: C1r/s (classical pathway), MBL-2 (lectin pathway), CFP (alternative pathway), F2 (coagulation pathway), C3 (the central component of complement system), and C9 (cell lysis) were quantified in the liver of marine medaka. Endogenous expression of all six complement system genes was found to be higher in males than in females (p < 0.05). Upon dietary exposure of marine medaka to BDE-47, expression of all six complement genes were downregulated in males at day 5 (or longer), whereas in females, MBl-2, CFP, and F2 mRNAs expression were upregulated, but C3 and C9 remained stable with exposure time and dose. A significant negative relationship was found between BDE-47 body burden and mRNA expression of C1r/s, CFP, and C3 in male fish (r = -0.8576 to -0.9447). The above findings on changes in complement gene expression patterns indicate the complement system may be compromised in male O. melastigma upon dietary exposure to BDE-47. Distinct gender difference in expression of six major complement system genes was evident in marine medaka under resting condition and dietary BDE-47 challenge. The immunomodulatory effects of BDE-47 on transcriptional expression of these complement components in marine medaka were likely induced by the parent compound instead of biotransformed products. Our results clearly demonstrate that future direction for fish immunotoxicology and risk assessment of immunosuppressive chemicals must include parallel evaluation for both genders.