FCT1-Teses
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Percorrer FCT1-Teses por Objetivos de Desenvolvimento Sustentável (ODS) "ODS 12 — Produção e Consumo Sustentáveis"
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- Evaluation of Ballan wrasse (LABRUS BERGYLTA) juvenile development with two commercial feeds at Mowi RensefiskPublication . Saúde, Carolina Serra; Oliveira, Catarina Cortes Valente de; Overrein, IngridFarmed Ballan wrasse ( Labrus bergylta ) is an efficient cleaner fish used for non medicinal de licing of Atlantic salmon in sea cages. The idea is replacing the use of wild caught individuals due to considerations for biodiversity and risk of overfishing local wrasse populations. Low g rowth rate during production has been a common struggle, resulting in fish not reaching the desired minimum size when they are to be shipped to different facilities for further development before being deployed to the salmon sea cages. Another difficulty is fins development, with the increased demand for Ballan wrasse in com mercial applications, Norwegian food authority is improving welfare regulation concerning this species. Due to pectoral fin erosion the mortality rate is exceedingly hi gh during the first weeks after deployment to the salmon pens, considering that fin erosion begins at the rearing facilities it becomes a point of important focus. The aim of this study was to find a more suitable feed for Ballan wrasse as well as ideal r earing conditions to improve survival and performance. This trial consisted in three tanks : control tank, Biomar II and Biomar III with 116 000, 88 000 and 90 000 fish respectively , with regular samples of 30 individuals over a three month period. Length, average weight, pectoral and caudal fin erosion were analyzed. Two commercial feeds were employed: Otohime, a well established finfish feed, and Biomar Symbio Plus, a relatively new and custom developed feed for Ballan wrasse . Also, hidings were introduced in the Biomar II tank for a portion of the trial. Results showed an even growth rate in the three groups during the first two months of the trial, and a pronounced growth was registered in the Biomar groups during the last month. It was distinctly observed that Biomar tanks held better fin health througho ut the trial, in contrast to Otohime. This study showed that by keeping a lower density during production the use of a specialized feed could improve the rearing quality and robustne ss of Ballan wrasse.
- Improvement of Chlorella sorokiniana to increase the production of lipophilic compoundsPublication . Lourenço, Cristiana Isabel Rodrigues; Varela, João Carlos Serafim; Schüler, Lisa MaylinMicroalgae represent a promising alternative to terrestrial plants as a natural source of bioactive compounds with anti-inflammatory and antioxidant properties. These compounds can provide health benefits and help to prevent chronic diseases, such as inflammatory bowel disease (IBD), when incorporated into functional foods, nutraceuticals, and pharmaceuticals. However, large-scale microalgae production faces challenges in ensuring economic viability. Alongside optimising process parameters, strain improvement is a promising approach to enhance productivity and fine-tune the accumulation of target compounds. The Algae4IBD project aimed at developing novel algal-based products to treat IBD, identified lipophilic extracts from Chlorella sorokiniana with high anti-inflammatory activity. Therefore, the thesis aimed to increase the production of lipophilic compounds in C. sorokiniana under heterotrophic conditions. To accomplish this, chemically induced random mutagenesis using ethyl methanesulfonate (EMS) and screening with lipid pathway inhibitors led to the isolation of several inhibitor-resistant colonies. Among them, mutant M9 emerged as the most promising strain with a light green colour, which is considered more appealing for consumers, distinguishing itself from other mutants. This novel M9 strain exhibited a specific growth rate of 1.41 ± 0.01 d−1, biomass productivity of 2.02 ± 0.07 g L−1d−1 and biomass concentration of 6.85 ± 0.12 g L−1, similar to that of the WT. In addition, as quantified by BODIPY505/515 fluorescence in flow cytometry and gravimetry, its lipid content of 18.1 ± 0.3% DW was 50% higher than the WT's, 11.8 ± 1.20% DW. A preliminary two-stage cultivation involving the induction of lipophilic compounds, through exposure to 30 g L⁻¹ sea salt and/or 140 μmol m⁻² s⁻¹ of light, did not significantly increase lipid accumulation (p > 0.05), suggesting further optimization is needed. Despite this, the promising characteristics of mutant M9, particularly its higher lipid content, make it a strong candidate for further development in the commercial production of microalgae-based products.
- Optimisation of aquaculture wastewater by halophytes cultivationPublication . Berge, Daan Louis ten; Marques, Cátia Andreia Lourenço; Custódio, Luísa Margarida BatistaThis thesis represents a comprehensive assessment regarding the cultivation of halophyte Salicornia ramosissima within aquaculture effluent-based systems and use of different water sources commonly available at aquaculture farms as treatments. Halophytes, recognised for their ability to thrive in saline environments, are gaining popularity for their versatile applications including culinary uses and source of secondary compounds with biorefinery potential. The experimental study spanned 6 weeks in a greenhouse at the Aquaculture Research Station of Olhão, Portugal. The setup entailed two production systems: semi-hydroponics and substrate mixture system consisting of potting soil and mud from a semi-intensive fishpond. Four treatments were applied in both systems. These involved water sources containing salinities 10, 20, and 35 PSU, the latter sourced from a semi-intensive pond system. In these treatments, plants received supplementary fertiliser. Additionally, the 35 PSU treatment was tested without supplementary fertiliser. Other treatments included water from a nearby brackish well (20 PSU) and its mixture with freshwater (10 PSU). The study aimed to assess how the two production systems combined with varying salinities and nutrient levels affect the growth, biochemical properties and nutritional content of S. ramosissima. Results indicated that the mud-based substrate system consistently produced higher biomass across all salinities compared to the semi-hydroponics system, particularly at 35 PSU. In the semi-hydroponics system, plants performed better at moderate salinity (20 PSU), while performance was more restricted at lower and higher salinities. Additional fertiliser in the high salinities (35 PSU) did not seem to affect growth or nutritional properties of biomass. Secondary metabolites were generally higher in biomass without supplementary fertiliser. The mud-based system appeared more robust, indicating suitability for high salinity environments. These results indicate that S. ramosissima could be used to effectively optimise aquaculture wastewater and act as biofilter whilst producing valuable biomass in highly saline conditions, promoting circular economy.