Sapientia
Repositório Científico da UAlg
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Enhancement of the antioxidant response in gilthead seabream (Sparus aurata) juveniles through dietary algal supplementation
Publication . Bolinhas, João Miguel Ramos; Teodósio, Rita; Engrola, Sofia
Fish in aquaculture are exposed to stressors such as handling and transport, which can lead to oxidative stress, compromising cellular integrity. Dietary intervention involving bioactive compounds can improve resilience and mitigate such damage. This study investigated the impact of algae-supplemented diets on the antioxidant and immune response of juvenile gilthead seabream following a short feeding trial and a subsequent stress challenge. A seven-day feeding trial was conducted using four diets: a control commercial-like diet (CTRL) and three alternatives supplemented with processed Tisochrysis lutea biomass (Tiso), Tisochrysis lutea biomass combined with Gelidium sp. extract (TisoG), and Tisochrysis lutea biomass and Skeletonema costatum extract (TisoS). Following the feeding trial, the challenge involved standardized events and infection with a pathogen (Photobacterium damselae subsp. piscicida) to assess if fish antioxidant responses were affected by the dietary treatments. Liver samples were collected post-feeding trial (Sampling 1-S1) and 6 hours post-infection (Sampling 2-S2) to evaluate growth performance, oxidative stress biomarkers, and expression of antioxidant and immune-related genes. Algae-supplemented diets had no negative effects on growth, feed efficiency, or survival. At S1, the TisoG group had significantly lower superoxide dismutase (SOD) activity and total antioxidant status (TAS) compared to other treatments. No differences were found in lipid peroxidation (LPO) or catalase (CAT) activity. At S2, SOD activity increased in Tiso, and TAS significantly increased in TisoG, with CAT and LPO remaining unaffected by diet. Gene expression at S1 showed no significant changes in oxidative stress markers, although igm was downregulated in Tiso and il-1β upregulated in TisoS. No differences were found in il-10, tnf-α, or hsp70. After S2, gpx1 was upregulated in CTRL and TisoG, sod2 was suppressed in TisoS, and nrf2 declined in all algae-fed groups. il-10 and tnf-α were highest in CTRL and significantly lower in TisoS. The Tisochrysis lutea and Gelidium extract diet was the most effective blend in enhancing antioxidant capacity and stress-related gene expression, especially after the challenge.
Abordagem integrada para a identificação, análise e mitigação de riscos ocupacionais no banco alimentar do Algarve: aplicação dos métodos Marat, Niosh e William T. Fine
Publication . Oliveira, Sérgio António Fonseca de; Sousa, António
O presente trabalho teve como objetivo identificar, analisar e mitigar os riscos ocupacionais associados às atividades logísticas desenvolvidas nas unidades de Faro e Portimão do Banco Alimentar do Algarve. Para tal, adotou-se uma abordagem metodológica integrada, que conjuga os métodos MARAT, NIOSH e William T. Fine.
A aplicação do MARAT permitiu uma avaliação sistemática dos riscos existentes, com a atribuição de Níveis de Intervenção (NI), destacando-se diversos riscos classificados como NI I e NI II, exigindo atuação imediata ou prioritária. A aplicação da equação de NIOSH permitiu calcular os Índices de Levantamento (IL), demonstrando a eficácia potencial de medidas corretivas simples. O método de William T. Fine foi aplicado aos riscos classificados como NI I, permitindo hierarquizar essas intervenções com base no custo e na urgência. As propostas incluem reorganização do layout, aquisição de equipamentos ergonómicos e formação dos colaboradores.
Os resultados revelaram contrastes significativos entre as duas unidades: Faro apresenta condições estruturais deficitárias, com layout improvisado e elevada exposição a riscos ergonómicos e mecânicos; Portimão, por sua vez, dispõe de uma estrutura mais adequada, mas enfrenta desafios na organização dos fluxos logísticos e no empilhamento em altura.
Foram propostas medidas corretivas ajustadas à realidade de cada unidade, incluindo soluções técnicas e organizacionais, formação prática, delimitação de espaços e aquisição de equipamentos ergonómicos de apoio. Este estudo reforça a importância da avaliação de riscos com recurso a metodologias combinadas, demonstrando a sua aplicabilidade em contextos logísticos do setor social, muitas vezes desprovidos de soluções sistematizadas. Os resultados obtidos permitem não só melhorar as condições de trabalho nas unidades analisadas, como também oferecer um modelo de referência replicável por outras organizações com dinâmicas semelhantes.
Effects of environmental enrichment on inhibitory control in juvenile gilthead seabream (Sparus aurata): a cognitive study using the cylinder task
Publication . Neves, Inês; Cabrera-Álvarez, María J.; Saraiva, João L.
Inhibitory control is a key component of executive function, influencing adaptability and decision-making in animals. Consequently, this study aims to investigate whether environmental enrichment (EE) enhances inhibitory control in juvenile gilthead seabream (Sparus aurata) using the cylinder task. As aquaculture rapidly expands to meet global food demands, the welfare of farmed fish species, such as seabream, has become a critical concern. EE, which involves introducing elements that stimulate fish physiologically and psychologically, has shown significant benefits in various species, including enhanced learning, memory, and stress resilience. This study used 40 juvenile seabreams housed in tanks with and without enrichment to test their cognitive abilities through a series of progressive learning phases. These phases culminate in the Cylinder Task, where fish are challenged to obtain food from a transparent cylinder using the two open ends, evaluating the inhibition of the urge to approach the reward through the transparent walls of the cylinder. All the individuals were previously screened for personality traits (i.e. either more proactive or more reactive). In this study, juvenile gilthead seabream reared in enriched environments exhibited higher behavioral engagement and faster learning during training, with significant improvements in task performance over trials. However, no significant differences in inhibitory control were observed between enriched and non-enriched groups during testing. Instead, larger fish and those with proactive traits, characterized by rapid decision-making and high exploration, performed tasks faster and more accurately. These findings suggest that while EE enhances motivation and learning, inhibitory control may be primarily driven by intrinsic factors like body size and personality rather than environmental complexity, and that adapting EE to individual traits could optimize welfare and efficiency in aquaculture.
Fine scale behaviour of Labrus bergylta in the National Park Illas Atlánticas of Galicia (NW Spain)
Publication . Brand, Lukas; Fernández, Alexandre Alonso; Abecasis, David
Understanding the spatial ecology and behaviour of coastal fishes is critical for the design of marine protected areas (MPAs). Acoustic telemetry, combined with advanced modelling approaches, provides high-resolution insights into residency, activity, and habitat use, key information for a proper design of spatial protection measures.
In this study, we acoustically tracked fifteen Labrus bergylta individuals over more than two years within the Atlantic Islands of Galicia National Park, generating over 4.5 million detections. After filtering and excluding fate dates, valid trajectories were reconstructed using Continuous-Time Correlated Random Walk models, yielding more than 3.1 million estimated positions. Residency analyses revealed that 67% (10) of individuals exhibited very high site fidelity (IWR ≥ 0.95), while others showed intermediate fidelity with occasional excursions beyond the array. Only one fish displayed virtually no residency.
Estimated activity spaces ranged from 6,870 to 23,120 m², with daytime ranges significantly larger than at night and peaking in late spring–summer, reflecting reproductive activity. Swimming speed was positively related to bottom temperature and showed seasonal variation as well as crepuscular peaks. Hidden Markov Models distinguished two behavioural states (resting vs. active), with an average activity budget of 56.5% resting and 43.5% active. State transitions were influenced by diel cycle and habitat type, though with strong inter-individual variability. Revisitation patterns revealed long-term fidelity to a small number of discrete core areas, located on rocky substrates and often shared across day and night.
Overall, L. bergylta exhibited a dual movement strategy of strong site fidelity interspersed with occasional exploratory excursions. These findings confirm the importance of structurally complex hard-bottom habitats as persistent refuges and support the effectiveness of fixed spatial protections. By linking fine-scale behaviour with habitat use over extended timescales, this study advances the ecological understanding of temperate reef fishes and provides robust evidence to inform the management and evaluation of coastal MPAs.
Assessment of wave overtopping at Praia da Vitória, Terceira, Azores, with SWASH model
Publication . Baddavidana, Dinush Shayaman Priyankera; Pinheiro, Liliana; Garzon, Juan L.; Zózimo, Ana Catarina
The primary objective of this dissertation is to enhance the accuracy of overtopping predictions using the SWASH (Simulating WAves till SHore) model, for inclusion in the Early Warning System (EWS), HIDRALERTA, currently operational in Praia da Vitória. While existing tools within HIDRALERTA offer valuable insights, they have limitations in accurately representing waves and overtopping details. To address these limitations, this research tested the capabilities of the SWASH model by simulating past storm events and typical wave conditions across the two-dimensional model of the entire port and bay areas with complex coastal structures and bathymetry. Outcomes of the simulations were compared to predictions from the NN_OVERTOPPING2 neural network and observed images from extreme events. In the SWASH model, coastal structures were modelled as impermeable layers, with bottom roughness incorporated to enhance energy dissipation from roughness and seepage. An unstructured triangular mesh was used for the computational domain. Manning’s coefficient for the outer slope of the south breakwater, with tetrapod armour units, was calibrated using a physical model test conducted in February 2025 at the National Laboratory of Civil Engineering (LNEC). The model was replicated in SWASH at prototype scale, using two test cases that resulted in overtopping for calibration. The results demonstrate that the SWASH model effectively simulates wave propagation and overtopping in harbour and bay areas, especially over complex coastal structures. Its accuracy in estimating wave propagation and overtopping is sensitive to wave energy interactions with the bottom and slopes, influenced by the Manning coefficient. While unstructured meshes enable large-domain simulations, the quality of the mesh affects both prediction accuracy and computational time. The model is stable when using implicit time integration but unstable with explicit methods. Despite some simulation instability, most simulations reached the maximum allowed simulation time on the National Distributed Computing Infrastructure (INCD) cluster. The model’s accuracy is heavily dependent on bathymetric data, with results generally aligning with NN_OVERTOPPING2 predictions and observed images from extreme events, although underpredictions can occur. Parallel processing is currently limited to structured grids in SWASH and, there is potential for efficiency improvements with unstructured meshes. Future studies should compare SWASH results with field data to fully assess its performance.