FCT1-Teses
URI permanente para esta coleção:
Navegar
Entradas recentes
- Microplastics in marine ecosystems: exposure, ingestion, and accumulation dynamics in seahorsesPublication . Melo, Catarina Simas de; Palma, Jorge Afonso Martins da; Andrade, José PedroO plástico tornou-se um elemento indispensável na vida humana, levando a um aumento exponencial da sua produção. No entanto, o seu consumo inconsciente e má gestão dos resíduos plásticos têm contribuído para que este se torne um dos principais poluentes nos ambientes marinhos costeiros. Estas partículas podem entrar no oceano através de diversas fontes, tanto terrestres (como sistemas de esgoto, vento e rios) como marítimas (como pesca e transporte marítimo). Uma vez no meio aquático, o plástico pode fragmentar-se em partículas menores, transformando-se em microplásticos (MPs) (< 5 mm), ou até nanopartículas (< 1 μm), afundando e acumulando-se nos sedimentos. Devido ao seu tamanho reduzido, os MPs podem ser ingeridos por uma grande diversidade de espécies marinhas, desde zooplâncton até grandes peixes, podendo causar impactos negativos no sistema digestivo, afetar a fisiologia dos organismos ou até levar à morte. A sua capacidade de bioacumulação e transferência entre diferentes níveis tróficos tem despoletado uma grande preocupação na comunidade científica, dado que podem representar riscos ecológicos. Os cavalos-marinhos, pertencentes à família dos singnatídeos, habitam em águas pouco profundas e são predadores oportunistas que recorrem predominantemente a pistas visuais para caçar. O seu focinho tubular que potencia o mecanismo de sucção que utilizam para capturar pequenas presas planctónicas como anfípodes, decápodes, isópodes e misidáceos, torna-os também, especialmente vulneráveis à ingestão de microplásticos. No entanto, os estudos sobre este tema ainda são recentes e escassos. Devido à semelhança entre o tamanho dos MPs e o das presas naturais dos cavalos-marinhos, a ingestão pode ocorrer por uma falta de identificação dos MPs, enquanto potenciais presas. Muitas espécies de cavalos-marinhos enfrentam ameaças populacionais, pelo que compreender os impactos específicos dos MPs nestes organismos é crucial para o desenvolvimento de estratégias de conservação, tanto da espécie como do seu habitat. A Ria Formosa é um sistema lagunar de baixa profundidade caracterizado por habitats de pradarias marinhas com uma grande biodiversidade. No entanto, tem vindo a sofrer de uma elevada pressão antropogénica devido às várias atividades que são desenvolvidas ao redor. Para além disso, são feitas descargas de esgotos neste ambiente e sendo que a sua hidrodinâmica é limitada por apenas algumas ligações ao oceano (sem total renovação da água), isto promove a retenção de poluentes o que o torna um ecossistema sensível. Aqui ocorrem espécies de elevada importância comercial e ecológica, onde se incluem as duas espécies de cavalos-marinhos nativas europeias – Hippocampus hippocampus e Hippocampus guttulatus – as quais pela sua biologia característica são também elas bastante vulneráveis a distúrbios antropogénicos e alterações ecológicas. Este estudo procurou: i) avaliar a presença, composição e características dos microplásticos em diferentes substratos da Ria Formosa, referenciados como habitats naturais para os cavalos-marinhos, e ii) analisar a ingestão de MPs pelo H. guttulatus, tanto em ambiente selvagem como em condições de cativeiro. Para tal, a exposição a MPs foi primeiramente avaliada através da análise de amostras dos substratos (erva marinha, Caulerpa prolifera e sedimento complexo), e de conteúdos gastrointestinais dos cavalos-marinhos selvagens. Posteriormente, realizou-se um estudo experimental em ambiente controlado para compreender a dinâmica de ingestão e acumulação de MPs. Para isso, consideraram-se dois tipos de alimentação (viva e congelada, individualmente fornecida em conjunto com uma mistura de MPs) para determinar a tipologia de ingestão (se acidental ou se voluntária), bem como o período de retenção (onde era apenas fornecido alimento sem MPs) para verificar possíveis processos de acumulação. Os resultados da análise dos diferentes substratos indicaram uma concentração significativa de MPs na Ria Formosa, especialmente no substrato sedimentar, sugerindo um possível aumento na contaminação ao longo dos anos quando comparado com estudos anteriores. A comparação dos dados sugere que fatores como pressão antropogénica, atividades industriais, turísticas e piscatórias, e processos hidrodinâmicos podem ter influenciado esta tendência crescente na acumulação de MPs nos substratos costeiros. A elevada exposição aos MPs leva também a que haja uma maior ingestão por parte dos animais, facto que se verificou através da análise do conteúdo do trato gastrointestinal (GIT) dos cavalos-marinhos selvagens e que mostrou uma presença de MPs em todos os animais observados independentemente do sexo ou tamanho. No entanto, verificou-se uma correlação positiva entre a quantidade de MPs ingeridos e o comprimento total dos indivíduos. Estes resultados reforçam a hipótese de que a ingestão de MPs pode estar mais dependente da disponibilidade e do comportamento alimentar do que de características individuais, como a personalidade trófica. Em termos de tipos de MPs, as fibras foram os mais comuns em ambos estudos feitos em ambiente natural (substratos e animais), as quais são frequentemente associadas a produtos têxteis, redes de pesca e descargas de águas residuais, o que justifica a sua ocorrência na Ria Formosa onde a influência dessas fontes é significativa. Ao analisar a distribuição das cores, os MPs pretos e azuis foram os mais comuns, tanto nas amostras de substrato como nos tratos gastrointestinais (GIT) dos cavalos-marinhos selvagens. No entanto, é admissível uma salvaguarda de erro nas classificações visuais e na diferenciação de cores devido a limitações no estereoscópio, e de potenciais processos de oxidação que podem ter ocorrido nos MPs observados. A nível de tamanhos, foi encontrada uma grande amplitude comprimentos, incluindo algumas fibras que se enquadraram na categoria mesoplásticos, mas que estariam enroladas e só quando esticadas atingiam esses tamanhos, o que justifica a sua ingestão pelos animais. Durante o estudo experimental em cativeiro, todos os cavalos-marinhos consumiram microplásticos tendo-se verificado uma maior ingestão de MPs quando alimentados com alimento vivo comparativamente com o alimento congelado. Isto pode ser explicado pelo aumento da atividade na captura de presas vivas (que ressuspende os MPs, aumentando a sua probabilidade de ingestão acidental) ou pelo facto de que em modo caça não terem tanto tempo para distinguir entre uma presa e MP, sugerindo que alguns MPs podem ser consumidos voluntariamente, mas possivelmente confundidos por uma presa durante a ação de caça. Coincidentemente, e tal como no ambiente natural, as fibras foram também o grupo de MPs mais consumido, reforçando a ideia que pelo seu tamanho e forma, estas podem ser confundidas com o alimento, mas também pela sua menor massa serem mais sensíveis ao movimento e podem ser ingeridas acidentalmente como foi possível observar. Entre os fragmentos fornecidos, os únicos que não foram consumidos foram os de cor azul, o que levanta a hipótese da existência de algum tipo de seletividade com base na cor. Por fim, foi também possível verificar que existiu retenção e possível acumulação devido à exposição prolongada a MPs. Estes resultados destacam a necessidade urgente de reduzir a contaminação por MPs nos ecossistemas marinhos, dado o impacto ecológico que podem ter em espécies vulneráveis como os cavalos-marinhos. Para futuras investigações, sugere-se o uso de metodologias mais precisas para a análise dos microplásticos que permitam não só uma caracterização mais exata, mas também a identificação do material de forma a ser possível deduzir as suas origens. Melhorias experimentais poderiam incluir uma maior gama de cores de MPs e condições de luz mais próximas do habitat natural, permitindo uma análise mais precisa de preferência e possível seletividade na captura de MPs.
- Effects of environmental conditions and seasonality on Barents Sea shrimp dynamics and consequences for stock assessmentPublication . Casla, Alex Rosa; Zimmermann, Fabian; Guerreiro, Pedro Miguel Guerreiro da CostaNorthern shrimp (Pandalus borealis) stock can be found across most of the Barents Sea, sustaining a large and valuable trawl fishery with an estimated sustainable catch of around 150,000 tonnes annually. The stock is monitored by Norway and Russia, and scientific advice is provided annually. However, the shrimp fishery in the Barents Sea has remained largely unregulated without any catch restrictions, with changes in catches mostly driven by economic factors, especially white fish accessibility and global shrimp prices. The current Northern shrimp stock assessment uses a biomass index from a spatiotemporal distribution model based on a relatively short survey time series. We evaluated whether including available time series of shrimp survey data from winter and environmental data could improve the model’s predictive potential and, thus, the quality of the assessment. While environmental variables did not provide a significant improvement in the biomass index model, the winter data aligned well with the summer data, providing valuable information on stock trends throughout the year. This research led to the implementation of a winter biomass index in the Barents Sea shrimp stock assessment model. The results showed that the inclusion of winter data provided similar estimates of biomass and fishing mortality com pared to the former model, but with increased predictive performance and accuracy. However, significant spatial and spatiotemporal random effects indicate that shrimp distribution and dynamics are linked to biotic and abiotic processes that are currently not explicitly accounted for in our modelling framework, which should be subject to further research. This project provides an important contribution to an improved stock assessment for the shrimp stock in the Barents Sea and, thus, sustainable catch advice. This is particularly relevant given the species’ important role in a changing arctic marine ecosystem, and the growing fishing pressure Northern shrimp is subjected to.
- First catalogs of humpback and fin whales in the Algarve regionPublication . Gennari, Ginevra; Castilho, RitaBaleen whales such as humpback (Megaptera novaeangliae) and fin whales (Balaenoptera physalus) are among the most highly migratory marine species. After experiencing severe population declines during the whaling era, both species are now showing signs of recovery. However, their complex movement patterns, wide-ranging distribution, and the absence of clearly defined population boundaries—particularly in the North Atlantic—pose challenges for monitoring and effective conservation efforts. While certain areas are recognized as key migratory corridors, the role of the southern Iberian coast, including the Algarve region in south of Portugal, remains largely unexplored. This thesis presents the first two photo-identification (photo-ID) catalogs of humpback and fin whales in the Algarve, establishing baseline data for this understudied region. The humpback whale chapter documents occurrences collected from 2009 to 2024 in collaboration with whale-watching companies and the Algarve Stranded Network (RAAlg). Fluke photo-ID allowed for the identification of 13 unique individuals. Comparison with the North Atlantic Humpback Whale Catalog identified matches with individuals previously sighted in distant locations, including Cabo Verde, the Ligurian Sea, and Scotland. Entanglement, particularly among juveniles, emerged as a recurrent anthropogenic threat. The fin whale chapter analyzes opportunistic data collected from 2020 to 2024, namely photo-ID and GPS boat tracks, resulting in a catalog of 86 unique individuals. Spatial capture-recapture modeling estimated a local population of 1,476 individuals suggesting that a large part of the population hasn’t been identified yet. Sightings peaked in spring and were often associated with feeding behavior, suggesting that the Algarve may serve as a seasonal foraging ground. However, low re-sighting rates across years suggest a transient rather than a resident use of the area. These findings highlight the ecological relevance of the Algarve for migratory baleen whales and underline the value of photo-ID and collaborative data collection with whale-watching companies. The two catalogs provide essential references for future research and inform conservation strategies in Portuguese waters.
- The BiP Chaperone from the Endoplasmic Reticulum of Zebrafish (Daniorerio) and Golden Hamster (Mesocricetus auratus)Publication . Roszik, Lilla; Melo, Eduardo PinhoThe Hsp70 family of molecular chaperones plays a crucial role in maintaining cellular proteostasis by promoting protein folding, transport, and degradation. One of its component proteins, the binding immunoglobulin protein (BiP), is an essential endoplasmic reticulum chaperone required for proper protein folding and stress response. The primary objective of this work was to clone the open reading frame of the BiP gene from zebrafish (Danio rerio), a model organism that is frequently used to study the molecular and genetic causes of human disorders. More than 70% of the genes between humans and zebrafish are similar, including many orthologs connected to neurodegenerative illnesses like Alzheimer's. For the sake of further functional investigations, the open reading frame of the zebrafish BiP gene was amplified and inserted into a bacterial expression vector. From zebrafish, the total RNA of caudal cell lines was extracted and reverse transcribed to create complementary DNA. The target DNA sequence was amplified by polymerase chain reaction (PCR) using specific primers for BiP. The golden hamster BiP ORF was removed from the backbone pQE10, and the amplified product was cloned into the vector. After transforming the recombinant plasmid into Escherichia coli DH5α for propagation and isolation, the insertion of the open reading frame of zebrafish BiP was sent to sequencing. Unfortunately, E coli recombines the zebrafish BiP ORF, contrary to the golden hamster ORF previously cloned into the same vector. Different E coli strains deficient in DNA recombination should be tested soon. This work aimed to establish the foundation for further investigations into the activity and biochemical characteristics of zebrafish BiP and its interactions with co-chaperones and client proteins in comparison with the mammalian BiP from golden hamster. At the longer term, we want to understand how the chaperone machinery of the endoplasmic reticulum has evolved in resolving protein aggregates associated with neurodegenerative diseases.
- New record of the coral-boring sponge Amorphinopsis cf. excavans in Kane´ ohe Bay, Hawai´iPublication . Pontes, João Diogo; Cunha, Regina Lopes da; Vicente, Jan; Toonen, RobThe Hawaiian archipelago is currently recognized as a hub of species introductions. In Kāneʻohe Bay, several marine alien species have been reported over the last decades, including sponges, which benefit from its nutrient-rich waters. Here we report the presence and the coral excavating habit of the Indo-Pacific sponge Amorphinopsis cf. excavans in the bay. A thorough traditional taxonomic assessment is performed, along with a genetic analysis of both ribosomal and mitochondrial genes, revealing the identity of the sponge. The results underscore the polyphyletic nature of the genus and highlight the need for an integrative approach to resolve its phylogenetic framework. Existing literature on A. excavans and its extended distribution range justify its classification as a species complex until further clarification. Limited dispersal capabilities of sponge larvae and the species’ encrusting ability suggest an introduction by integrating the fouling community of trans-Pacific vessels. The sponge is actively boring into the two primary reef-building species of coral in the bay - Montipora capitata and Porites compressa, therefore posing a significant environmental threat to Hawaiʻi’s native ecosystem. Considering the expected increase in bioeroding sponges under future climate change scenarios, the development of management strategies is advised.
- Restoration of seagrass meadows in Ria Formosa: overcoming and assessing human impactPublication . Scala, Margherita; Paulo, DiogoSeagrass meadows are vital coastal ecosystems providing numerous ecological services, yet they are increasingly threatened by anthropogenic pressures. This study investigates the effectiveness of a transplantation-based restoration strategy for Zostera noltei in the intertidal SE1 meadow of Ria Formosa (Portugal), an area recently impacted by construction activities, mooring infrastructure, and recreational boating. Over a seven-month period, both donor and receiver sites were monitored using field surveys and drone-based imagery to assess seagrass percentage cover, shoot density, shoot height, and daily growth rates. Initial quadrat-level data indicated promising trends in percent cover, however, inclusion of the last three monitorings revealed that no statistically significant increase had occurred (p = 0.1142). Both shoot density and height declined, suggesting limited restoration success at the meadow scale. This was corroborated by UAV-derived monitoring, which documented a decline in total cover from 18.5% to approximately 8%, underscoring the importance of integrating multiscale assessments. Variance in daily growth rates among receiver units revealed both synchronized and heterogeneous growth periods, with no significant influence of plot or patch identity (ANOVA, p > 0.9). In contrast, donor sites exhibited consistent recovery with a significant increase in percent cover (p = 0.0001) and no impact from sediment refill treatments. Mooring assessments revealed significantly reduced seagrass structure in buoyed areas compared to controls, with no correlation between distance from anchor and vegetation parameters. These findings suggest that chronic, small-scale disturbances may suppress recovery below ecological thresholds, even after removal of major stressors. This study highlights the importance of comprehensive disturbance management and multiscale monitoring to improve restoration outcomes and long-term resilience of seagrass ecosystems.
- Physiological effects of hooking in longline fisheries in Algarve and the welfare implications for fishPublication . West, Katie Georgina Harriet; Guerreiro, Pedro MiguelThis thesis investigates the physiological responses and welfare implications of teleost fish subjected to artisanal longline fisheries in the Algarve region. The study focuses on understanding how different post-capture treatments and varying soak times impact fish vitality and stress markers, including glucose, lactate, cortisol, and osmolality. Both on-vessel fieldwork and in-house experiments were conducted to assess the physiological stress responses of Sparus aurata and other sparid species such as Diplodus sargus, Diplodus vulgaris, and Pagellus erythrinus. The results revealed no significant species-specific differences in vitality decline, with all species showing a sharp decrease in vitality overtime. Changes in physiological parameters showed similar pattern for the three species, with increases in lactate and osmolality over time, reaching the highest values at 120 min after capture, while a general decline in glucose concentrations was observed. Cortisol was already elevated at capture and remained high throughout, increasing only in D. sargus. The in-house experiments demonstrated that neither post-capture treatment (Dry, Ice, Ice Slurry) nor soak duration (0, 30, 90 minutes) significantly influenced vitality loss, reinforcing that time was the primary driver. Physiological stress indicators showed significant increases in lactate and osmolality over time, with a sharp glucose spike under ice treatment and stable but variable cortisol levels between treatments. This study contributes to the growing body of research on fish welfare in wild-capture fisheries by applying a function-based welfare approach. The findings provide valuable insights into the physiological responses of fish post-capture and offer recommendations for improving fish handling practices in artisanal longlining, with the ultimate goal of minimising stress and enhancing fish welfare. The study underscores the importance of minimising exposure time post-capture to reduce physiological stress in the artisanal longline fishery of the Algarve.
- Utilização do QGIS, do Mergin Maps e de uma base de dados espacial para a criação de um Atlas de Biodiversidade na Área Protegida Privada da Faia BravaPublication . Castro, João António Mendes de; Loureiro, Nuno Manuel de Figueiredo de Santos; Monteiro, António da Cruz Espinha de AlmeidaEsta tese de mestrado teve como objetivo criar, através da aplicação Mergin Maps, uma ferramenta prática e eficiente para a recolha, no terreno, de dados. É a partir do QGIS que os projetos são criados e mantidos, e, em conjunto com o Mergin Maps, permitem a sincronização dos dados. Adicionalmente foi criada uma base de dados espacial. Os casos de estudo escolhidos foram a Área Protegida Privada da Faia Brava, no distrito da Guarda, e a Ilha do Maio, Cabo Verde, através das atividades da Fundação Maio Biodiversidade. Os casos de estudo permitiram testar e avaliar as capacidades da aplicação móvel em contexto real, no terreno, e identificar as potencialidades desta solução QGIS | Mergin Maps. No caso da Área Protegida Privada da Faia Brava, o projeto criado em QGIS para a utilização na aplicação móvel Mergin Maps teve como objetivo a recolha de observações da biodiversidade. Esta solução informática estará ligada a uma base de dados geoespaciais, onde será armazenada, de forma estruturada e organizada, toda a informação. Foi organizado um Atlas de Biodiversidade com a presença ou a não deteção das espécies, a partir dos dados recolhidos através do Mergin Maps e também de outras bases de dados. Para a ilha do Maio foi também desenvolvido um projeto para a aplicação móvel Mergin Maps, com o objetivo de facilitar a recolha de registos de biodiversidade. Nesse caso de estudo toda a informação recolhida é gerida no QGIS, uma solução mais simples do que a adotada para o caso anterior. Foi compilada a metodologia associada à utilização do QGIS e do Mergin Maps em dois tutoriais. Um deles detalha as etapas específicas para a criação de um projeto QGIS | Mergin Maps (tutorial do criador), enquanto o outro aborda a utilização da aplicação móvel no terreno (tutorial do utilizador).
- Storm processes and impacts in high energy geologically controlled barriersPublication . Kümmerer, Vincent; Ferreira, Óscar; Loureiro, CarlosCoastal barriers are dynamic sedimentary landforms exposed to the impacts of coastal storms, with storm-induced erosion and shoreline retreat controlled primarily by the hydrodynamic forcing and barrier morphology. When located in storm-dominated environments, coastal barriers are typically attuned to energetic wave forcing, but extreme events can still result in significant impacts. Moreover, in geologically controlled barrier systems, less studied non dynamic geological controls such as the underlying bedrock topography or sediment availability can also mediate the morphological response to storms. Aiming to investigate the relative importance of geological controls on storm processes and impacts in coastal barriers along high wave energy coasts, this study integrates morphological and hydrodynamic data, satellite imagery and process-based numerical modelling to explore storm response in the Outer Hebrides barriers in the northwest of Scotland. Improvements to storm identification methods, to assessment and morphodynamic modelling of morphological change at contemporary timescales, resulted in more comprehensive characterisation of storm processes and impacts in high energy, geologically controlled barriers. Results indicate that there is an increasing trend in storm duration in the western coast of Scotland, and that more than the intensity of wave forcing, water level has a critical influence on storm response in barriers with a wide and shallow nearshore profile. However, variation in foreshore configuration, particularly the presence and height of intertidal rock surfaces, can induce a shift in the primary control of storm response from the hydrodynamic forcing to the geological control. Thus, geological constraints are shown to be important controls on storm-induced morphological response in coastal barriers, leading to spatial variability in shoreline change. Overall, the results of this thesis outline that the incorporation of geological controls in storm impact assessments, particularly in the context of rising sea-levels, is critical to better understand storm-induced changes in coastal barriers on high-energy, geologically constrained coastal environments.
- Molecular and cellular mechanisms of ioxynil and diethylstilestrol disruption of cardiac and thyrocyte development and homeostasisPublication . Li, Yifeng; Power, Deborah M.Endocrine disrupting chemicals (EDCs) are compounds that interfere with endocrine systems, induce alterations in their functionality, and give rise to numerous adverse effects that have been documented in animals and ecosystems. The herbicide ioxynil (IOX) and the synthetic estrogen diethylstilbestrol (DES) are two chemicals still in use, which are environmentally relevant contaminants that act as EDCs. In humans, prenatal exposure to DES is associated with an increased incidence and prevalence of cardiac defects. IOX may disrupt the thyroid system by binding to transthyretin (TTR) and provoke thyroid tumors in rats. The main objective of this thesis was to determine how IOX and DES disrupt the crosstalk between the developing thyroid gland and cardiovascular system in zebrafish. An invertebrate bioindicator species, Mytilus coruscus, was included in the study to comprehend the effects of IOX and DES on a bivalve and contribute to a broader understanding of endocrine disruption in both invertebrate and vertebrate organisms. The core achievements were a) characterization of heart function and cardiovascular and thyroid development in IOX- and DES-exposed zebrafish embryos. Transcriptome analysis of vascular endothelial cells of zebrafish embryos that elucidated compound-specific molecular effects associated with endothelial functions; b) identification of the effects of IOX and DES on the physiology of the heart and thyroid in juvenile zebrafish; c) characterization of the effects of IOX and DES on cardiac performance and shell growth of juvenile M. coruscus. Transcriptome analysis of juveniles revealed genes related to cardiac function, neuroendocrine regulation, and detoxification were affected. The findings revealed that IOX and DES exposure had a disruptive effect at a molecular and functional level on the cardiovascular system of a vertebrate (zebrafish) and an invertebrate (M. coruscus), suggesting that these chemicals function as cardiovascular disruptors in both phyla. Overall, the study highlights for the first time the potential at both a molecular and functional level of adverse outcomes for both fish and bivalves of exposure to IOX and DES in the environment, suggesting they are EDCs with broad impacts across multiple organisms.