Detection of larvae of Toxocara canis in milk: an experimental study in rabbits.

Toxocariasis, caused most commonly by Toxocara canis, is an important cosmopolitan zoonosis. Paratenic hosts have been employed to provide knowledge regard to the transmission of toxocariasis. Transmammary transmission in murine experimentally infected was observed based on the recovery of larvae from the tissue. The aim of this study was to evaluate the possibility of transmammary transmission of Toxocara canis in rabbits by detecting larvae directly in milk. Seventeen sexually mature virgin white New Zealand female rabbits were divided into two groups. Twelve animals were orally inoculated with 1,000 T. canis embryonated eggs (infected group), and five animals remained uninfected (control group). One month following the infection, the females were mated. Manual collection of 500 ?L of milk from each rabbit was performed on days +7, +14 and +21 of lactation for three consecutive lactations. The recovery of larvae was determined via a centrifuge-sedimentation technique using ether and formalin solutions. ELISA test was run to confirm the production of anti-T. canis antibodies (IgG) by infected rabbits. The presence of larvae was observed in milk samples from 5 (41.7%) of the 12 infected rabbits. The total number of recovered larvae was 20, ranging from 1 to 4 larvae per lactation/rabbit. Larvae were recovered exclusively on days 7 and 14 of lactation. Recovery was verified in different lactations. No significant difference was observed with respect to the number of larvae either in the same lactation period or in different lactation periods. Anti-T. canis antibodies were detected in all infected rabbits. In conclusion, the presence of larvae in rabbit milk samples suggests the possibility of galactogenic transmission of T. canis in paratenic hosts. Moreover, the technique employed in this study allows for the recovery of larvae directly from milk.

Horizontal distribution of invertebrate larvae around the oceanic island of Gran Canaria: the effect of mesoscale variability

In October 1991, the horizontal distribution of invertebrate larvae was studied in the waters surrounding the island of Gran Canaria (Canary Islands). The cruise was typified by the presence of three recurrent mesoscale hydrographic structures: a cyclonic eddy southwest of the island, a warm lee region downstream of the island and the offshore boundary of an upwelling filament from the African coast reaching the southeast of the island. Decapod larvae were the most abundant group. In general, a rather high spatial variability was found. The horizontal distribution of the invertebrate larvae groups showed that the highest values of abundance occurred in an elongated zone around the island oriented in the overall direction of flow, leeward and windward of the island, while the lowest values occurred off the eastern and western flanks of the islands. On the other hand, Stomatopoda and Mollusca larvae showed a distribution associated with the boundary of the upwelling filament and decapod larvae of pelagic species were distributed around the eddy structure. Our results suggest specific retention mechanisms for the larvae of neritic invertebrate populations that are related to the particular physical oceanography around Gran Canaria. Se estudió la distribución horizontal de las larvas de invertebrados alrededor de la isla de Gran Canaria (Islas Canarias) en octubre de 1991. La campaña se caracterizó por la presencia de tres fenómenos oceanográficos de mesoescala recurrentes: un remolino ciclónico al suroeste de la isla, la estela cálida a sotavento de la misma y el borde de un filamento proveniente del afloramiento africano situado al sureste de Gran Canaria. Las larvas de crustáceos decápodos fueron las más abundantes. En general, las larvas de los diferentes taxa estudiados mostraron una gran variabilidad en cuanto a su distribución espacial. La distribución horizontal de las larvas de los diferentes grupos de invertebrados mostró que las densidades más altas se registraban alrededor de la isla en la banda cercana y orientada hacia el suroeste, en la dirección del flujo, mientras que los valores más bajos se encontraron en el norte y en los flancos este y oeste de la isla. Por otro lado, las larvas de estomatópodos y moluscos presentaron una distribución asociada al frente del filamento, mientras que las larvas de decápodos pelágicos se distribuyeron en torno al remolino ciclónico. Los resultados obtenidos sugieren la existencia de mecanismos de retención específicos para el mantenimiento de las poblaciones insulares, relacionados con los procesos físicos de mesoescala predominantes

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.

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.

Use of different commercial Artemia sp. Enrichements in Octopus Vulgaris, paralarval rearing at initial planctonic phase: effects on growth, survival and fatty acid composition of the paralarvae

[EN] Octopus "paralarvae", are planktonic, swim actively and have high metabolic rates, requiring large quantities of live prey of adequate motility and nutritional quality ( Iglesias et al., 2000; Navarro and Villanueva, 2000, 2003). During the planktonic phase, they undergo strong morphological changes, after which the octopuses start settling to the bottom. The potential of Octopus vulgaris as candiadate for diversification of marine aquacultures are mainly due to its high food conversion rate and fast growth.( Iglesias et al 2006). Despite the research effort taken until now, paralarval rearing of O. vulgaris still suffers high mortalities which limited the industrial culture of this species. The main problems in the paralarval rearing stages are the high mortality rates and poor growth. These are attributed to the lack of standardized culture techniques and nutritional deficiencies in the diet of paralarvae, especially in n-3 highly unsaturated fatty acids (n-3 HUFA). The objective if this experience was to test different commercial live prey enrichment to improve nutritional quality of the artemia.

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.

Embryonic and larval development of haliotis tuberculata coccinea reeve: an indexed micro-photographic sequence

[EN] First description of the complete embryo and larval development of the Canarian abalone (Haliotis tuberculata coccinea Reeve.) was conducted along 39 stages from fertilization to the appearance of the third tubule on the cephalic tentacles and illustrated in a microphotographic sequence. Eggs obtained by induced spawning with hydrogen peroxide from the GIA captive broodstock were stocked at a density of 10 eggs/mL and kept at 23 0.5 BC for 62 h until the formation of the third tubule. Live eggs and larvae were continuously observed on a 24 h basis at a 3400 magnification under transmitted light. At each stages, specific morphological features, illustrated by microscopic photographs, were described, as well as the time required for their apparition. Fertilized eggs diameter was 205 8 mm (mean SD), whereas length and width of larvae ready to undergo metamorphosis were 216.6 5.3 mmand 172 8.8 mm, respectively. Knowledge on the larval morphological development acquired through this study will contribute to the improvement of larval rearing techniques for this abalone species.

Oxidative stress in sea bass (Dicentrarchus labrax) larvae fed on high DHA microdiets. Involvement of several antioxidant nutrients

Programa de Doctorado, Acuicultura: Producción controlada de organismos acuáticos

Optimun phospholipids and antioxidant levels to develop novel microdiets for gilthead seabream larvae

Programa de doctorado: Acuicultura: Producción controlada de animales acuáticos

Identification, Abundance and Rearing of Mysids of Gran Canaria: aplication to laboratory and oceanographic respiratory metabolism studies

Programa de doctorado en Oceanografía