Browsing by Author "Melo, Ricardo"
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- Modelling the distribution of a commercial NE-Atlantic Sea Cucumber, Holothuria mammata: demographic and abundance spatio-temporal patternsPublication . Félix, Pedro M.; Pombo, Ana; Silva, Francisco Azevedo e; Simões, Tomás; Marques, Tiago A.; Melo, Ricardo; Rocha, Cristina; Sousa, João; Venâncio, Eliana; Costa, José L.; Brito, Ana C.There is an increasing demand for sea cucumbers, for human consumption, mainly from Asian markets and, as a consequence, NE-Atlantic species are now new targets for exploitation and exportation. Holothuria mammata is one of the most valuable species in Europe. However, the lack of historical economic interest in this species in most European countries has also led to a lack of studies concerning biological and ecological aspects on wild populations and this is a major issue for stock management. This study aims to determine the temporal and spatial patterns of distribution of H. mammata, considering its abundance and demographic structure in a NE-Atlantic area, SW Portugal, as a function of environmental conditions. For that, a population from a marine protected area was followed for 1 year at 1.5-month intervals. Throughout the coastal area, six sites were selected and at each sampling campaign three random transects per site and substrate (rock and sand) in which all H. mammata individuals were counted and measured. For each site and survey several environmental parameters of interest, from the water column, the sediment and substrate cover, were also measured. Generalized Linear Models were used to model the spatial and temporal distribution of the species according to environmental conditions, to determine the species’ habitat preferences. The distribution models indicate that abiotic and biotic parameters of the water column are not the main drivers shaping the distribution of H. mammata. The species has a patchy distribution, and its habitat preferences depend on environmental stability, the presence of shelter and habitat complexity, which is more important for smaller, more vulnerable, individuals, while bigger size classes tend to venture more into less stable environments in an opportunistic fashion. The knowledge of these population traits is determinant to develop stock management measures, which are now urgent to prevent the depletion of commercial sea cucumber populations in the NE-Atlantic. Sustainable fisheries policies should be developed and start by considering to delimit fishing areas and periods, considering the species spatial and temporal distribution patterns.
- The effects of stocking density on physiological traits in Holothuria forskali broodstockPublication . Sousa, João; Félix, Pedro M.; Brito, Ana C.; Venâncio, Eliana; Silva, Francisco Azevedo e; Simões, Tomás; Raposo, Andreia; Neves, Marta; Narciso, Luís; Melo, Ricardo; Pombo, AnaThe high demand of sea cucumbers in international markets, mostly based in Asia, has left a deep impact on the natural stock of many species, leading to an investment in aquaculture techniques in order to mitigate these impacts. This study aimed to determine the effects of stock density in rearing broodstock of Holothuria (Panningoturia) forskali Delle Chiaje, 1823, a common species in the Mediterranean Sea and eastern Atlantic with commercial value. To do so, two different density treatments were selected: 1 kg/m2 and 2 kg/m2. The trial took place over five months and individuals were fed a mixture of frozen microalgae (Tetraselmis sp. and Phaeodactylum tricornutum). At the end of the trial, the effects of stock density on the individuals’ condition were assessed by analysing different variables, namely their fresh and gutted weight, evisceration and mortality rates, gonadosomatic index and oocyte size and even biochemical content, such as protein and lipid content in muscle bands. No significant differences were found between density treatments regarding any of the parameters assessed, aside from mean oocyte diameter. Individuals from the lower-density treatment presented a smaller mean oocyte diameter, supplied with fewer oocytes, than individuals in both the higher-density treatment and the baseline group. Regardless of this one difference, all trial individuals were able to maintain their elevated gonadal developmental stage for a full period of five months past their reproductive peak, with female holothurians subjected to the higher-density treatment showing signs of increasing vitellogenic reserves, a considerable advantage in aquaculture broodstock rearing.
- Undaria pinnatifida (U. pinnatifida) bioactivity: Antioxidant, gastro-intestinal motility, cholesterol biosynthesis and liver cell lines proteomePublication . Pedro, Bernardo; Guedes, Laura; André, Rebeca; Gaspar, Helena; Vaz, Pedro; Ascensão, Lia; Melo, Ricardo; Serralheiro, Maria LuisaUndaria pinnatifida is a brown alga, largely used as food in oriental countries. The purpose of this work was to analyze several bioactivities that might be present in different food preparations, relating them with the compounds present in the extracts. Aqueous extracts cooked, like a soup, as well as used in a salad, by simulating U. pinnatifida digestion with pancreatin were prepared. The soup preparation had anti-acetylcholinesterase activity as well as 3-hydroxy3-methyl-glutaryl coenzyme A reductase inhibition capacity, the use of 1 mg/mL, for both enzymes, caused 50% enzyme activity inhibition. The extracts produced changes in HepG2 cell proteome, mainly in the 148 kDa proteins. U. pinnatifida in salads hardly released phlorotannins to the digestive tract. The in vitro studies suggested that a soup prepared from this seaweed could deliver bioactive compounds, phlorotannins and small peptides that may facilitate the gastro-intestinal motility and reduce the cholesterol biosynthesis.