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Percorrer por autor "Teles, Diogo Miguel Carreiras"

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  • Valorisation of agricultural and mussel waste through the development of experimental diets and analysis of their effect on the growth of the polychaete Hediste diversicolor (O.F. Müller, 1776)
    Publication . Teles, Diogo Miguel Carreiras; Pombo, Ana Margarida Paulino Violante; Baptista, Teresa Maria Coelho
    The agriculture and aquaculture industries are essential for food production, but they also produce waste that can harm nearby ecosystems. Therefore, new strategies must be created and adopted to valorise the different types of waste produced by various industries, in line with the principles of the circular economy. The polychaete Hediste diversicolor is a commercially valuable organism used as fishing bait and supplementary aquaculture feed. Furthermore, this species has been utilised by several researchers as a means of recycling waste from various species within the context of aquaculture production, as well as waste from biogas production. This study aimed to use H. diversicolor to transform two types of waste — olive oil production waste (wet olive pomace) and mussel production waste — into valuable biomass. To this end, two trials were conducted. In the first trial, four diets with two different lipid compositions (6% and 12%) and sources (wet olive pomace and rapeseed oil) were tested directly on polychaetes. The second trial involved testing IMTA cultivation of this polychaete species alongside the mussel Mytilus edulis through three treatments involving different quantities of cells (1×107, 5×107 or 20×107 cells per individual) of Tetraselmis chuii and Chaetoceros gracillis (in a 50:50 ratio). At the end of both trials, the polychaetes from each treatment were captured and weighed to calculate their survival and growth parameters (SR, SGR, AGR, final biomass and mean wet weight). In the first trial, the survival rate was similar for diets 2 and 4 (respectively 6% and 12% lipids, without wet olive pomace), but significantly lower for diet 3 (12% lipids and with wet olive pomace) compared to the other treatments (p-value < 0.05). The highest growth was observed in diet 2, and the diet with the worst results in relation to these parameters was treatment 3. In the second trial, there were no high mortality rates in any treatment, and polychaete growth was higher in treatments (2 and 3) with greater amounts of food supplied to the bivalves, with most parameters being statistically higher than in treatment 1 (p-value < 0.05). Thus, the first trial of this study concluded that wet olive pomace is not an ideal ingredient for a H. diversicolor diet. However, further testing of smaller amounts of this waste in polychaete diets would be necessary to better assess whether this is an effective method of treating this type of waste. The second trial concluded that the polychaete H. diversicolor could successfully feed on waste produced by M. edulis mussels, and that this type of IMTA has potential for mussel waste treatment, since treatment 3 (20 ×107 cells/ind.) produced good growth parameters.
    2026-02-12Dissertação de mestrado Acesso aberto Ver mais