Aquaculture production in Spain represents 3 % of the whole world production and 25 % of the Euro... more Aquaculture production in Spain represents 3 % of the whole world production and 25 % of the European production. This productive reality evidences decided bets, although erratic, started in 1982 when "Programa Especial de Investigación y Desarrollo en Acuicultura" reached "Boletín Oficial del Estado". This Plan has been the main revitalizing element of the business sector, providing specialised human resources, knowledge and developments. Moreover, this Plan was also sponsor of other activities at both State and Autonomic Administration levels with a clear incidence not only on the aquaculture research but also on the whole Marine Science in Spain. During the last years, planning in the Aquaculture I+D has been subjected to distortions provoked by a transhumance between marine sciences and technologies and the animal production (breeding and fisheries or food and agriculture resources). When it is added to this an obvious disorganization between institutions in their funding or execute actions of I+D, it will be observed that prospective of the White Book of the Aquaculture in Spain from 2000 is far from being transformed in actions to promote that. Finally, the predictable continuity of the actions in I+D in the actuation line of previous National Plans evidenced symptoms of exhaustion and inadequacy to the actual needs of aquaculture.
Population dynamics on mussels growing on suspended culture depend mainly on the balance of sever... more Population dynamics on mussels growing on suspended culture depend mainly on the balance of several processes: mortality and/or dislodgements from the ropes, recruitment and growth. The negative effect of overcrowding on mussel growth and survival has been widely studied. Other works have addressed the effect of population size on recruitment on bottom beds. This study aims to provide insight into the processes underlying population dynamics. To this purpose, we analyzed the effect of stocking density on mussel growth, survival and seed settlement, and the post-settlement interaction between adults and recruits in suspended culture. The temporal pattern of the variables involved in population dynamics was fitted by GAM models, which in contrast with parametric models does not assume any prior relationships between variables. Our results show that mussel growth and survival depend on a trade-off between competition for resources at high densities and the risk of great settlements in less crowded adult mussel populations. Intracohort competition increased with stocking density, while seed settlement, which increases the risk of mussel dislodgements and leads to intercohort competition, was higher at moderate stocking densities. Post-settlement competitive pressures were driven by total population density and size composition. Both intracohort competition in adults and asymmetric competition between adults and recruits increase with higher adult-recruit ratios. All these density-dependent processes should be considered in future management strategies and research experimental designs.
Desde que Young (1923) detectó la amilasa en el estilo cristalino de los moluscos bivalvos, se ha... more Desde que Young (1923) detectó la amilasa en el estilo cristalino de los moluscos bivalvos, se ha registrado la presencia de varios tipos de actividad enzimática tanto en el estilo cristalino como en la glándula digestiva de bivalvos (Brock y Kennedy 1992;.
Aquaculture production in Spain represents 3 % of the whole world production and 25 % of the Euro... more Aquaculture production in Spain represents 3 % of the whole world production and 25 % of the European production. This productive reality evidences decided bets, although erratic, started in 1982 when "Programa Especial de Investigación y Desarrollo en Acuicultura" reached "Boletín Oficial del Estado". This Plan has been the main revitalizing element of the business sector, providing specialised human resources, knowledge and developments. Moreover, this Plan was also sponsor of other activities at both State and Autonomic Administration levels with a clear incidence not only on the aquaculture research but also on the whole Marine Science in Spain. During the last years, planning in the Aquaculture I+D has been subjected to distortions provoked by a transhumance between marine sciences and technologies and the animal production (breeding and fisheries or food and agriculture resources). When it is added to this an obvious disorganization between institutions in their funding or execute actions of I+D, it will be observed that prospective of the White Book of the Aquaculture in Spain from 2000 is far from being transformed in actions to promote that. Finally, the predictable continuity of the actions in I+D in the actuation line of previous National Plans evidenced symptoms of exhaustion and inadequacy to the actual needs of aquaculture.
Population dynamics on mussels growing on suspended culture depend mainly on the balance of sever... more Population dynamics on mussels growing on suspended culture depend mainly on the balance of several processes: mortality and/or dislodgements from the ropes, recruitment and growth. The negative effect of overcrowding on mussel growth and survival has been widely studied. Other works have addressed the effect of population size on recruitment on bottom beds. This study aims to provide insight into the processes underlying population dynamics. To this purpose, we analyzed the effect of stocking density on mussel growth, survival and seed settlement, and the post-settlement interaction between adults and recruits in suspended culture. The temporal pattern of the variables involved in population dynamics was fitted by GAM models, which in contrast with parametric models does not assume any prior relationships between variables. Our results show that mussel growth and survival depend on a trade-off between competition for resources at high densities and the risk of great settlements in less crowded adult mussel populations. Intracohort competition increased with stocking density, while seed settlement, which increases the risk of mussel dislodgements and leads to intercohort competition, was higher at moderate stocking densities. Post-settlement competitive pressures were driven by total population density and size composition. Both intracohort competition in adults and asymmetric competition between adults and recruits increase with higher adult-recruit ratios. All these density-dependent processes should be considered in future management strategies and research experimental designs.
Desde que Young (1923) detectó la amilasa en el estilo cristalino de los moluscos bivalvos, se ha... more Desde que Young (1923) detectó la amilasa en el estilo cristalino de los moluscos bivalvos, se ha registrado la presencia de varios tipos de actividad enzimática tanto en el estilo cristalino como en la glándula digestiva de bivalvos (Brock y Kennedy 1992;.
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