Trade-off between offspring number and offspring size in the marine copepod Euterpina acutifrons at different food concentrations

collected females of the marine copepod Euterpina acutifrons monthly from November 1994 to January 1996 at a station located in Ria de Vigo (Spain). A trade-off between egg size and egg number was found. As food concentration measured as mean fluorescence in the water column diminished, mean number of eggs per sac carried per female decreased, whereas mean egg size increased. An experiment carried out with adult females cultured at different food concentrations confirmed the field results, and also showed that as egg size increased, there, was an increase in naupliar body length at hatching; nauplii developed faster to first copepodite stage, and net reproductive rate was higher. Therefore, the reproductive strategy of directing more energy toward offspring size rather than offspring number, at low food concentrations, clearly increases reproductive success.Postprin

Viabilidad del cultivo del pulpo

Versión del edito

Pulpo

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Growth of octopus (Octopus vulgaris) males and females under culture conditions

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Aplicación de diferentes métodos de marcado externo a Octopus vulgaris Cuvier, 1797 con referencia especial a las marcas de tipo T y a los discos de Petersen

En este trabajo se presentan datos de persistencia y efectos provocados por una gran variedad de estilos de marcas (loops, marcas de conejos, cinchas, cintas plásticas flexibles, lancetas, discos de Petersen, marcas de tipo T, marcas plásticas circulares, banderillas plásticas rectangulares, soportes de bisutería, pines comerciales y quemaduras con nitrógeno líquido) aplicadas al cefalópodo Octopus vulgaris Cuvier, 1797 sometido a condiciones de cultivo. Tras una primera revisión de los resultados obtenidos con los diferentes sistemas de marcado se concluye que los discos de Petersen y las marcas de tipo T son los más aconsejables. Ambos muestran una retención adecuada después de un mes (90 y 80 % respectivamente), una persistencia máxima de tres meses, un coste similar y ambos son detectados externamente con facilidad. Sin embargo, los discos de Petersen producen heridas considerables y requieren un proceso de inserción más laborioso, por lo que, finalmente, el sistema considerado más adecuado fue la inserción de marcas de tipo T en el brazo III izquierdoThis paper presents a study on the persistence and effects caused by a wide variety of types of tag (loops, rabbit tags, girths, flexible plastic bands, small darts, Petersen disks, T-bar anchor tags, circular plastic tags, rectangular plastic flags, jewellery pins, commercial badges, and burning with liquid nitrogen) applied to the cephalopod Octopus vulgaris Cuvier, 1797, under culture conditions. Preliminary analysis of the results obtained with the different tagging systems indicates that Petersen disks and T-bar anchor tags are the most suitable types. Both provide adequate retention after 1 month (90 % and 80 %, respectively), a maximum persistence of three months, a similar cost, and they are easily recognised externally. However, Petersen disks can produce serious injuries, and require a more laborious insertion process. Therefore, in the final analysis, the insertion of T-bar anchor tags in left arm III can be considered the most appropriate systemThis work has been carried out with a grant from the Inter-ministerial Commission for Science and Technology and the Instituto Español de Oceanografía, as part of the CYTMAR 97-0323 projec

Crecimiento larvario de sardina (Sardina pilchardus Walb.) en laboratorio, bajo diferentes condiciones de alimentación

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Experimental Feeding and Growth of Turbot (Scophthalmus maximus L.) from 0.5 To 2.7 Kg in Galicia (NW Spain)

Two groups of turbot, Scophthalmus maximus L., of 0.5 and 1.2 kg initial mean weight were fed a semimoist diet containing fish, fish meal and vitamin-mineral complex. The trial was carried out in tanks of 16 cubic meters, for aperiod of a year. Resul ts on feed conversion index and growth in weight are give