Sapientia
UAlg Scientific Repository
About Sapientia
SAPIENTIA brings together all scientific publications produced by teachers, researchers, and students (theses and dissertations) from the University of Algarve and cooperating entities (ULSALG-Unidade Local de Saúde do Algarve and Ciência Viva network centers in the Algarve) and aims to maximize their visibility, ensure easy access to this collection, improve the public impact of the scientific activity of the University and other entities, as well as ensure the preservation of their memories.
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Recent Submissions
Joint model for zero-inflated data combining fishery-dependent and fishery-independent sources
Publication . Silva, Daniela; Menezes, Raquel; Araújo, Gonçalo; Rosa, Renato; Moreno, Ana; Silva, Alexandra; Garrido, Susana
Accurately identifying spatial patterns of species distribution is crucial for scientific insight and societal benefit, aiding our understanding of species fluctuations. The increasing quantity and quality of ecological datasets present heightened statistical challenges, complicating spatial species dynamics comprehension. Addressing the complex task of integrating multiple data sources to enhance spatial fish distribution understanding in marine ecology, this study introduces a pioneering five-layer Joint model. The model adeptly integrates fishery-independent and fishery-dependent data, accommodating zero-inflated data and distinct sampling processes. A comprehensive simulation study evaluates the model performance across various preferential sampling scenarios and sample sizes, elucidating its advantages and challenges. Our findings highlight the model’s robustness in estimating preferential parameters, emphasizing differentiation between presence–absence and biomass observations. Evaluation of estimation of spatial covariance and prediction performance underscores the model’s reliability. Augmenting sample sizes reduces parameter estimation variability, aligning with the principle that increased information enhances certainty. Assessing the contribution of each data source reveals successful integration, providing a comprehensive representation of biomass patterns. Empirical application within a real-world context further solidifies the model’s efficacy in capturing species’ spatial distribution. This research advances methodologies for integrating diverse datasets with different sampling natures further contributing to a more informed understanding of spatial dynamics of marine species.
Criação da certificação profissional brasileira de operadores de eventos
Publication . Moreira, Marcelo Augusto Torres; Neves, Paulo
Este trabalho de mestrado apresenta a criação da Certificação Brasileira de Operadores de Eventos, um marco para a profissionalização e regulamentação do setor de eventos no Brasil. No capítulo 1, faz-se um enquadramento teórico, analisando o mercado de eventos, o sistema de ensino brasileiro e os modelos de certificações. O capítulo 2 detalha a estrutura da certificação, que inclui um Curso de Aperfeiçoamento de Competências e um Exame de Competências, ambos fundamentados nas normas ABNT e ISOs. No capítulo 3, abordam-se as possibilidades futuras relacionadas à implementação da certificação, incluindo sua internacionalização e parcerias estratégicas com entidades do setor de eventos. Esse projeto visa elevar os padrões de qualidade, segurança e sustentabilidade dos eventos, tornando-os referenciais no mercado.
Glyphosate: a terrestrial threat to marine plants? a study on the seagrass zostera marina
Publication . Deguette, Alizé; Pes, Katia; Vasconcellos, Bernard; Costa, Monya; Silva, João; Barrote, Isabel
Glyphosate-based herbicides (GBHs) are extensively used worldwide, raising concerns about their potential effect on non-target aquatic ecosystems. This study investigated the short-term physiological effects of a commercially available GBH on the seagrass Zostera marina under controlled mesocosm conditions. Z. marina individuals were exposed to three concentrations of glyphosate (0.165, 51, and 5100 mg L−1 ) for 4 days, and the impacts on photosynthetic performance, growth rate, photosynthetic pigments content and energy metabolism were assessed. Exposure to 5100 mg L−1 of glyphosate caused rapid water acidification and complete plant mortality within 24 h. Exposure to 51 mg L−1 of glyphosate significantly impaired photosynthetic efficiency and foliar growth rate. Energy availability, photosynthesis and photosynthetic pigments content were highly disrupted at both higher concentrations. Exposure to 0.165 mg L−1 of glyphosate decreased the foliar chlorophyll a/b ratio. These findings show that Z. marina can potentially be threatened by the presence of GBHs even at lower concentrations and underscore the necessity for monitoring herbicide pollution in coastal waters to protect seagrass habitats and associated ecosystems. Further research is needed to assess long-term effects and the role of herbicide formulations in mediating toxicity.
Potential protective role of amphibian skin bacteria against water mold saprolegnia spp.
Publication . Costa, Sara; Proença, Diogo Neves; Alves, Artur; Morais, Paula V.; Lopes, Isabel
Amphibian populations have experienced a severe decline over the past 40 years, driven primarily by environmental pollution, habitat destruction, climate change, and disease. This work reports, for the first time, saprolegniosis in Pelophylax perezi egg masses and saprolegniosis in amphibians in Portugal. After isolation and phylogenetic analysis, the pathogen was identified as Saprolegnia australis. Following this, the present work intended to screen a collection of P. perezi skin bacteria for the existence of bacterial strains with inhibitory action against the newly identified S. australis SC1 and two other species, Saprolegnia diclina SAP 1010 UE and Saprolegnia australis SAP 1581 UE. The results showed that various bacterial species could inhibit the growth of these three species of oomycetes. Bacteria with the most significant antagonistic action against Saprolegnia spp. predominantly belonged to the genus Bacillus, followed by Serratia, Pseudomonas, and Aeromonas. Despite variations in bacterial diversity among frog populations, the present study also demonstrated the presence of bacteria on frogs’ skin that were capable of inhibiting Saprolegnia spp., as evidenced by in vitro challenge assays. These findings highlight the protective function of bacteria present in amphibian skin. The observed bacterial diversity may contribute to the metabolic redundancy of the frog skin microbiome, helping to maintain its functional capacity despite shifts in the community composition. Additionally, the study found that, when providing a more advantageous environment for pathogen growth—in this case a peptone–glucose (PG) medium instead of R2A—the percentage of bacteria with moderate-to-strong antagonistic activity dropped by 13% to 4%. In conclusion, the presence of bacteria capable of inhibiting Saprolegnia spp. in adult individuals and across different environmental conditions may contribute to lowering the susceptibility of frog adults towards Saprolegnia spp., compared with that in the early stages of development, like the tadpole or egg stages.
Is connectedness between commodity volatility indices and G-7 stock market returns the same across return quantiles?
Publication . Hanif, Waqas; El Khoury, Rim; Hadhri, Sinda
This study examines the connectedness and spillover effects among G7 stock markets, oil and gold volatilities from January 1, 2017, to June 16, 2022. By employing an in-quantile spillover approach, the study contributes to the existing literature by providing a comprehensive analysis of the linkages between these markets. The findings reveal that spillover effects are highly dynamic and vary significantly across different quantiles of the return distribution. During periods of market turbulence—such as the Covid-19 pandemic, trade tensions, and geopolitical conflicts—spillover intensity increases, indicating heightened market interdependence. The Japanese stock market and Gold volatility index (GVX) consistently act as net recipients of shocks, whereas the stock markets of Canada, France, Germany, Italy, the UK, and the USA serve as net transmitters. While long-term diversification opportunities appear limited, gold and oil exhibit effective hedging properties for short-term investors across various market conditions. From a policy perspective, these findings underscore the importance of monitoring market interdependencies, particularly during crisis periods. Policymakers should implement coordinated strategies to mitigate systemic risks in financial markets, especially in times of heightened uncertainty. Investors should consider short-term hedging strategies using gold and oil to minimize risk exposure during market downturns. Furthermore, financial regulators in G7 countries should enhance surveillance mechanisms to preempt excessive spillovers that may threaten financial stability.