[en] The macroalgal work in the framework of the ECOAQUA project has two main objectives: 1) Reduction of nutrient discharges of culture systems using macroalgae as biofilters and 2) Valorisation of macroalgae coming from these systems. To obtain basic knowledge about the chemical composition of effluents from different aquaculture systems, a programme of series of intensive 24 h samplings of the efluents of cultures of different species of animals. Changes in concentrations of dissolved and particulate inorganic and organic nutrients were analised. Among others, the high concentrations of nutrients, inorganic nitrogen in particular in cultures of animals (in this case octopus) fed with natural feed compared to artificial feed stood out. We assessed the capacity for growth and cultivation of various species of macroalgae for integration in biofilters and concluded that Ulva and Gracilariopis appear to have the best perspective for cultivation at medium/large scale in the context of integrated systems due to their resistance against changes of ambient conditions and their high growth rates. A typical feature of integrated systems, apart from high nutrient concentrations are high levels of CO2 and bicarbonate in the water caused by the respiration of the animals. An experiment was carried out comparing integrated system conditions (high carbon) versus a control and its effects on the growth rate, photosynthesis and valuable components in U. rotundata and G. longissima. A higher growth rate was found for U. rotundata and higher carbohydrate levels in cultures growing in high CO2. We conclude that the effect of elevated CO2 depends on the species and clearly affects the biochemical composition of the algae. Finally, the experimental planning for the remaining period of the project was presented. Acknowledgments: This work was supported by project P08-AGR-3695, Junta de Andaluc&iacute;a, Spain and by Interreg Project ECOAQUA, financed by the EDRF (European Regional Development Fund). www.juntadeandalucia.es/agriculturaypesca/ifapa/ecoaqua

[es] El trabajo con macroalgas en el marco del proyecto ECOAQUA tiene dos objetivos principales: 1) Reducci&oacute;n de vertidos de nutrientes por sistemas de cultivo utilizando macroalgas como biofiltro y 2) Valoraci&oacute;n de macroalgas procedentes de dichos sistemas. Para obtener conocimientos b&aacute;sicos sobre la composici&oacute;n qu&iacute;mica de los efluentes de distintos sistemas de cultivos, se llev&oacute; a cabo un programa de series de muestreos intensivos de 24 horas de efluentes de cultivos de varias especies. Se analizaron los cambios en concentraciones de nutrientes inorg&aacute;nicos y org&aacute;nicos, disueltos y particularizados. Se destacaron las elevadas concentraciones de nutrientes, nitr&oacute;geno inorg&aacute;nico en particular, en cultivos de animales (en este caso pulpo) alimentado con comida natural, comparandolos con animales alimentado con un pienso artificial. Se evaluaron la capacidad de crecimiento y cultivo de varias especies de macroalgas para su integraci&oacute;n en biofiltros y se concluy&oacute; que Ulva y Gracilariopis parecen tener mejor perspectiva para cultivos a escala mediana/grande en el contexto de sistemas integrados por su resistencia a cambios ambientales y sus altas tasas de crecimiento. Una caracter&iacute;stica t&iacute;pica de sistemas integrados, aparte de altas concentraciones de nutrientes, son los elevados niveles de CO2 y bicarbonato que tiene el agua a causa de la respiraci&oacute;n de los animales. Se realiz&oacute; un experimento comparando condiciones de sistemas integrados (carbono alto) frente a un control y sus efectos en la tasa de crecimiento, fotos&iacute;ntesis y componentes valiosos en U. rotundata y G. longissima. Destac&oacute; la mayor tasa de crecimiento en U. rotundata y un nivel elevado de carbohidratos en cultivos creciendo en condiciones de alta CO2. Se concluye que el efecto de CO2 elevado depende de la especie y claramente afecta a la composici&oacute;n bioqu&iacute;mica de las algas. Finalmente, se presentaron los experimentos planeados para el &uacute;ltimo tramo del proyecto. Acknowledgments: This work was supported by project P08-AGR-3695, Junta de Andaluc&iacute;a, Spain and by Interreg Project ECOAQUA, financed by the EDRF (European Regional Development Fund). www.juntadeandalucia.es/agriculturaypesca/ifapa/ecoaqua &nbsp;