Effect of larval density and feeding sequence on meagre (Argyrosomus regius Asso, 1801) larval rearing

[EN] Meagre, has been proposed as a candidate for marine finfish diversification on commercial aquaculture (Quémèner, 2002, Mateos, 2007). Despite of the elevated on growing potential, the most important bottleneck of this specie is related to the limited production of fry. Larval rearing of this species, is performed mainly adapting seabream culture techniques with different success (Roo et al., 2007) However, since limited information about the optimal feeding sequences and nutritional requirements of meagre is available, more research is needed on larval rearing protocols and nutrition. Present results (elevated larval growth rate, high survival, short rotifers period) are very promising for a successful implementation at industrial scale, which helps to solve the continues lack of fry of this specie in the Mediterranean and Canary islands.

Nuevas aportaciones al estudio de la organogénesis en larvas de corvina (Argyrosomus Regius Asso, 1801)

La corvina (Argyrosomus regius) es un teleósteo de la familia Scianidae, que en los últimos años ha despertado un gran interés en acuicultura por su rápido crecimiento y la calidad de su carne. A su vez, se trata de una de las especies denominadas ?nuevas? que no pertenecen a la familia de los espáridos, y permite diversificar la oferta de la piscicultura marina. Las primeras aportaciones al estudio histológico del desarrollo larvario de esta especie fueron realizados por Jiménez et al. (2007). El presente trabajo incrementa la información existente, durante los dos primeros meses de vida de esta especie, lo que permitirá optimizar el cultivo larvario. Para ello se analiza la relación entre el desarrollo de sistema digestivo, la vejiga natatoria y el sistema visual. Los resultado demuestran que la corvina es una especie de rápido desarrollo y muy susceptible a las condiciones de cultivo durante su fase larvaria, condicionando éstas su crecimiento. A su vez el presente estudio ratifica que las características morfológicas y la organogénesis están directamente relacionadas con la longitud de la larva, independientemente de la edad de la misma.

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.

Effect of rearing system intensiveness on biological features, culture performance and larval quality of meagre (Argyrosomus regius Asso, 1801) larvae

[EN]Meagre, Argyrosomus regius A., is a new species for aquaculture in south Atlantic and Mediterranean regions, that can reach a mean fresh weight of 8.02±2.51g. at 95dah. However, hatchery techniques must be improved to optimize culture performance and larval quality. Eggs of meagre were cultured under intensive (75 indv.l-1 in 2m3 tanks) and semi-intensive system (7.5 indv.l-1 in 40m3 tanks) to evaluate the effect of the intensification on biological features, stress resistance and skeletal deformities. At 30dah, despite in semi-intensive system reared larvae a higher total length (19.08± 2.3mm vs 16.00±1.54mm), dry body weight (13.09± 2.43mg vs 6.46±0.52mg), and survival after the activity test (75.0± 13.8% vs 53.3±11.5%) was found, the use of intensive systems were also very suitable and cost-effective for larval rearing of this species

Testing zooplankton secondary production against growth in the marine mysid, "Leptomysis lingvura" (G.O. Sars, 1866)

[EN]Zooplankton growth and secondary production are key input parameters in marine ecosystem modelling, but their direct measurement is difficult to make. Accordingly, zooplanktologists have developed several statistical-based secondary production models. Here, three of these secondary production models are tested in Leptomysis lingvura (Mysidacea, Crustacea). Mysid length was measured in two cultures grown on two different food concentrations. The relationship between length and dry-mass was determined in a pilot study and used to calculate dry-mass from the experimental length data. Growth rates ranged from 0.11 to 0.64 , while secondary production rates ranged from 1.77 to 12.23 mg dry-mass . None of the three selected models were good predictors of growth and secondary production in this species of mysid.

Can zooplankton secondary production models predict growth in the marine mysid Leptomysis lingvura (G.O. Sars, 1866)?

[EN]Zooplankton growth and secondary production are key input parameters in marine ecosystem models, but their direct measurement is difficult to make. Accordingly, zooplanktologists have developed several statistical-based secondary production models. Here, three of these secondary production models are tested in the marine mysid Leptomysis lingvura (Mysidacea, Crustacea). Mysid length was measured in two cultures twice a day, which were grown on two different food concentrations. Growth rates ranged from 0.11 to 0.64 day-1, while secondary production rates ranged from 1.77 to 12.23 mg dry- mass day-1. None of the three selected models were good predictors of growth and secondary production in this mysid species.