Optimización del cultivo de diatomeas bentónicas para el cultivo de post-larvas de abalón ("Haliotis tuberculata coccinea" Reeve, 1846)

[EN] Diatom cell quantity and their biochemical composition vary among species and are greatly affected by harvest stage or culture conditions. Biometric parameters, growth, attachment capacity and variations in biochemical composition of four species of benthic diatoms (Amphora sp., Navicula incerta, Nitzschia sp. and Proschkinia sp.) were studied. For biochemical analysis the diatoms were harvested at different stages, in log and stationary phase of growth. The culture conditions were identical for all the experiments, benthic diatoms were cultured during 7 days in F/2 medium at 28.5 ± 1.4 ºC, at different original inoculating densities (50000, 100000, and 250000 cell mL-1), under continuous light of 5403 ± 649 Lux provided by cool white fluorescent lighting. The cultures were neither aerated nor agitated. These results show that the specific density of 10000 cell mL-1 was the best for weekly production: Proschkinia sp. reached the highest cell density of 5.81 x 106 cells mL-1 and Amphora sp. had the highest cell attachment capacity with 12000 cell mm-2, in stationary phase of growth. Protein and lipid content were higher in log phase than in stationary phase for the four diatoms. Amphora sp. in log phase of growth had the highest lipid content of 9.74% dry weight (DW). Polyunsaturated fatty acid (PUFA) content ranged from 23.25% to 38.62% of the total fatty acids (TFA), and the four diatoms tested were richer in n-3 PUFA than in n-6 PUFA. All the diatoms had significant quantities of 20:5n-3 (EPA) ranging between 12.69% and 17.68% of TFA. Benthic diatoms play an important and critical role in abalone culture as they are the principal food source of abalone post-larvae. Therefore, it is necessary to improve diatom quantity and quality to optimize post-larval nutrition and the consistency of production, resulting in an increase in growth and survival of abalones.

Effect of rearing techniques over, survival growth and skeletal abnormalities development in red porgy (Pagrus Pagrus) larvae

[EN] Red porgy is one of the most interested new species for Spanish and other Mediterranean countries. Although no industrial procedures for fry production has been yet developed. The aim of this work was to develop an industrial scale larval rearing protocols testing the viability of two different rearing techniques (semi-intensive vs intensive) in pilot scale facilities. The second objective was to obtain information about the contribution of rearing system to the apparition of morphological abnormalities such as lordosis, opercular deformities and upper/lower jaws shortening which are considered as quality descriptors in commercial marine fish fry production and seem to be related with larval culture conditions in early larval stages. For that purpose, two different larval rearing systems semi-intensive and intensive were compared using the same live feed enrichments. Biochemical composition of larvae, preys and commercial products was analysed. At 50 days post hatching six hundred fish per treatment was individually studied under stereoscope and abnormalities frequency recorded. At 95 days post hatching fry were soft X ray monitored as well. Survival and abnormalities frequency were similar between treatments although a better growth in terms of total length was obtained in the semi-intensive system.

Early life of the abalone Haliotis tuberculata coccínea : development, settlement and growth

Programa de doctorado: Acuicultura