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Browsing by Author "Martins, Diogo Miguel Marreiros"

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  • Integrating seaweed in a marine fish RAS
    Publication . Martins, Diogo Miguel Marreiros; Quintã, Raquel; Aragão, Cláudia
    Aquaculture is, nowadays, one of the sectors with a crucial impact on the human food supply. Sustainability in this sector has become a primary goal and is directly connected to recirculating aquaculture systems. These systems hold great promise for the future, but improvements in water quality are needed due to the high accumulation of metabolic waste. Water quality may be improved by integrating macroalgae into these systems, as they have excellent bioremediation capabilities. This study aimed to implement an Integrated Recirculating Aquaculture System (IRAS) with Ulva sp. and fish to assess macroalgae bioremediation capacity and improve water quality and fish performance in comparison to a fish Recirculating Aquaculture System (RAS). Macroalgae capacity in bioremediation highly depends on their growth and nutrient availability in the system. So, this work included sampling of dissolved nutrients and weekly samplings for assessing biomass production, at different densities (1.0, 1.5, and 2.0 kg FW m-2), and assessment of nitrogen content in the macroalgae produced. Results showed that the highest growth rate was found for Ulva sp. stocking density 1.0 kg FW m-2, while N yield did not differ between the stocking densities tested. The Ulva sp. improvement in water quality parameters was not significant when compared to RAS treatment. Fish performance was not significantly different between treatments and no differences were observed in hematological and histological parameters. The gills presented some anomalies but were classified with minor signs of pathology. The results demonstrate that lower Ulva sp. stocking densities resulted in higher growth, indicating that this macroalgae can be a potential candidate for IRAS, but more research is needed to use the bioremediation capability to improve water quality in these systems.
    2024-10-29Master thesis Open access Show more