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- Security technologies for wireless access to local area networksPublication . Faraj, Khaldoun Esmaeil; Barradas, ÁlvaroIn today’s world, computers and networks are connected to all life aspects and professions. The amount of information, personal and organizational, spread over the network is increasing exponentially. Simultaneously, malicious attacks are being developed at the same speed, which makes having a secure network system a crucial factor on every level and in any organization. Achieving a high protection level has been the goal of many organizations, such as the Wi-Fi Alliance R , and many standards and protocols have been developed over time. This work addresses the historical development of WLAN security technologies, starting from the oldest standard, WEP, and reaching the newly released standard WPA3, passing through the several versions in between,WPA, WPS, WPA2, and EAP. Along with WPA3, this work addresses two newer certificates, Enhanced OpenTM and Easy ConnectTM. Furthermore, a comparative analysis of the previous standards is also presented, detailing their security mechanisms, flaws, attacks, and the measures they have adopted to prevent these attacks. Focusing on the new released WPA3, this work presents a deep study on both WPA3 and EAP-pwd. The development of WPA3 had the objective of providing strong protection, even if the network’s password is considered weak. However, this objective was not fully accomplished and some recent research work discovered design flaws in this new standard. Along with the above studies, this master thesis’ work builds also a network for penetration testing using a set of new devices that support the new standard. A group of possible attacks onWi-Fi latest security standards was implemented on the network, testing the response against each of them, discussing the reason behind the success or the failure of the attack, and providing a set of countermeasures applicable against these attacks. Obtained results show that WPA3 has overcome many of WPA2’s issues, however, it is still unable to overcome some major Wi-Fi vulnerabilities.
- Compared physiological performances of Caulerpa prolifera and native seagrasses of Ria FormosaPublication . Hofman, Jan Dirk; Barrote, Isabel; Silva, JoãoSeagrasses are among the most important and also mostly threatened ecosystems in the marine environment. Seagrass loss can occur in their competition with other macrophytes, like invasive macroalgae. These pose a serious threat and present numerous consequences to their new environment. Among those that can affect seagrasses, Caulerpa sp. are one of the most recognized genus. Different mechanisms can grant them a competitive advantage over seagrasses, resulting in partial or even complete replacement. Therefore, knowing how Caulerpa sp. functions and interacts with a new environment is crucial, especially in a system like Ria Formosa, where three of the four European seagrass species can be found. We aimed to study and compare different photo-physiological components of the subtidal seagrasses Cymodocea nodosa and Zostera marina and of the macroalgae Caulerpa prolifera along diel cycles, while at the same time identifying possible consequences of their interaction, using a mesocosm experiment. The first experiment was performed over the course of two days (48 hour cycle), collecting samples for biochemical analysis at pre-dawn and solar noon at the end. The mesocosm experiment involved planting Z. marina and C. prolifera separately and mixed. After 4 weeks, photosynthetic performance was tested using photosynthesis-irradiance curves and rapid light curves, and samples for biochemical analysis were collected. The seagrasses revealed higher effective quantum yield and non-photochemical quenching, mainly related to their xanthophyll pigments, while C. prolifera displayed a typical shade-adapted response. Furthermore, it displayed a different carbohydrate usage regime, which was related to its higher respiration rates. Although no different overall photosynthetic performance was detected in the interaction of the species, starch content in Z. marina rhizomes was significantly lower when C. prolifera was present. This work gives initial insight on the physiological performance of C. prolifera in Ria Formosa.
- Service or disservice? The role of marine coastal bioengineers in plastic debris trappingPublication . Cozzolino, Lorenzo; Nicastro, Katy; Santos, Carmen B. de losHoje em dia, a poluição plástica é cada vez mais reconhecida como uma séria ameaça ambiental e económica que compromete a biodiversidade dos ecossistemas marinhos e os serviços que estes prestam. A crescente entrada de lixo plástico nos oceanos exige esforços imediatos para coletar dados sobre a ocorrência, abundância e dispersão de detritos plásticos para uma melhor avaliação ambiental e para impulsionar práticas de gestão. Para alcançar esses resultados, é necessário um foco importante em ecossistemas-chave, como os formados por bioengenharia. Os bioengenharia são espécies que modulam a disponibilidade de recursos diminuindo o estresse ambiental ou aumentando a complexidade do habitat, influenciando positivamente as espécies em sua comunidade, resultando em um aumento geral da biodiversidade. No entanto, há uma lacuna de conhecimento sobre o papel potencial dos bioengineiros costeiros marinhos na captura de detritos plásticos que exige atenção. Ao aumentar a complexidade do habitat, os engenheiros dos ecossistemas costeiros, tais como ervas marinhas, marismas e macroalgas rizófitas, podem agir indirectamente como sumidouros de plástico dos oceanos. Além disso, se o acúmulo de detritos plásticos em ecossistemas formados por bioengenheiros for realmente promovido, isso pode ter, por sua vez, efeitos deletérios sobre sua fauna associada. A exposição direta dos organismos que vivem dentro das estruturas dos bioengineiros a altas concentrações de poluentes plásticos pode ter efeitos negativos sobre sua saúde. Em particular, o risco de ingestão acidental de microplásticos pode ser aumentado em bivalves com hábitos de alimentação por filtração que ocorrem em habitats bioengenharia. É importante notar que, em zonas onde as espécies comerciais de bivalves são directamente colhidas de ecossistemas naturais, como os prados de ervas marinhas, o potencial destes habitats para actuarem como sumidouros de plástico pode, em última análise, afectar a saúde humana. Aqui, eu investiguei o papel potencial dos bioengenharia costeira como sumidouros de macro e microplástico. Assim, quantifiquei a ocorrência, tipologia e abundância de detritos plásticos em ervas marinhas intertidais (Zostera noltei), ervas marinhas subtidais (Cymodocea nodosa e Zostera marina), macroalgas rizófitas (Caulerpa prolifera) e sapais intertidais (Sporobolus maritimus) habitando uma lagoa costeira antropizada. Hipotetizei que estes bioengenheiros acumulam mais macroplásticos entre as frondes das copas e microplásticos no sedimento superficial do que as manchas adjacentes de sedimentos nus. No geral, não encontrei diferenças significativas entre a capacidade de aprisionamento de bioengenharia vegetal e sedimentos nus laterais. Uma diferença significativa foi detectada apenas entre a abundância de macroplásticos em S. maritimus e seu sedimento pelado intertidais lateralmente. No entanto, apesar da falta de diferença estatística significativa, os sedimentos coletados em Z. noltei intertidais (0.019 ± 0.017 n MPs g-1) e S. maritimus (0.024 ± 0.019 n MPs g-1) resultaram ligeiramente menos contaminados por microplásticos do que os das espécies sub-mareais C. nodosa e C. prolifera (0.035 ± 0.027 n MPs g-1 e 0.034 ± 0.025 n MPs g-1). Em geral, o microplástico mais abundante detectado foi a fibra (86,5%) e a cor mais comum foi o azul (45%). Por outro lado, a avaliação macroplástica revelou S. maritimus (0,220 ± 0,157 macroitems m-2) e C. prolifera (0,048 ± 0,061 macroitems m-2) com a maior concentração macroplástica por número (n macroitems m-2) e a menor por massa (0,513 ± 0,428 g macroitems m-2 e 0,848 ± 1.056 g macroitems m-2, respectivamente), enquanto C. nodosa (0,013 ± 0,021 macroitems m-2) e Z. noltei (0,013 ± 0,020 macroitems m-2) apresentaram a menor abundância macroplástica (n macroitems m-2) e a maior massa (16,431 ± 39,752 g macroitems m-2 e 6,326 ± 14,827 g macroitems m-2, respectivamente). No total, 61,4% dos detritos macroplásticos encontrados eram fragmentos. Em seguida, avaliei se os bioengineiros intertidais e subtidais aprisionaram diferentes quantidades e tipologias de macro e microplásticos. Para tanto, comparei as espécies intertidais Z. noltei e S. maritimus com as espécies subtidais C. nodosa/Z. marina e C. prolifera. Hipotetizei que o padrão de distribuição do tipo plástico difere entre-marés e bioengenharia sub-marítima de acordo com a forma como a sua formação estrutural modifica as condições ambientais locais. Em geral, eu esperava encontrar mais plástico em espécies sub-mareais devido à sua maior exposição aos poluentes presentes na coluna de água. No entanto, nenhuma diferença significativa foi detectada entre a quantidade e a tipologia dos macro e microplásticos acumulados em habitats intertidais e subtidais. Para fornecer uma declaração completa da deposição de plástico nos prados dos bioengineiros, eu também quantifiquei a ocorrência, tipologia e abundância de microplásticos aderidos nas copas dos bioengineiros. Para atingir este objectivo, analisei as lâminas das folhas dos cinco bioengineiros visados: Z. noltei, S. maritimus, Z. marina, C. nodosa e C. prolifera. Hipotetizei que parte dos microplásticos aprisionados nos bioengineiros não atingiria a superfície do sedimento, mas poderia potencialmente aderir às folhas de ervas marinhas. A expectativa era encontrar um número maior de MPs na superfície das folhas das espécies sub-mareais devido à sua maior exposição aos poluentes presentes na coluna de água. Diferenças significativas na abundância de microplástico nas folhas dos bioengineers intertidais e subtidais confirmaram a minha hipótese, com as espécies subtidais aprisionando mais detritos do que as intertidais. Em geral, a maior concentração microplástica foi encontrada nas folhas de C. prolifera (0,0559 ± 0,0936 MPs cm-2) e Z. noltei (0,0529 ± 0,1238 MPs cm-2), seguido por C. nodosa (0,0198 ± 0,0308 MPs cm-2) e Z. marina (0,0114 ± 0,0113 MPs cm-2). A menor contaminação foi registrada em S. maritimus com 0 MPs cm-2. No geral, os microplásticos detectados nas folhas eram todas fibras e as cores mais comuns eram o azul (36%). Finalmente, para entender se altas concentrações de plástico nos bioenginheiros e nos sedimentos laterais nus podem afetar a fauna associada, avaliei a ocorrência e abundância de microplástico ingerido por espécies bivalves rentáveis (Ruditapes decussatus, Polititapes sp. e Cerastoderma sp.), comumente colhidas na Ria Formosa. Encontrei que MPs ocorrem em altas concentrações em todas as espécies bivalves investigadas. Especificamente, Ruditapes decussatus continha em média 18,4 ± 21,9 MP itens g-1 (u.i.) tecido e exibiu a maior concentração de MP por peso, Cerastoderma sp. e Polititapes sp. seguidos de 11,9 ± 5,5 MP itens g-1 (u.i.) e 10,4 ± 10,4 MP itens g-1 (u.i.), respectivamente. Globalmente, 88% das MP encontradas eram fibras sintéticas, a maioria das quais eram azuis (51,6%). Os polímeros mais representados foram o polietileno (PE) e o poliestireno (PS). O número inesperadamente elevado de microplásticos registados em bivalves sugere que este sistema lagunar semi-fechado está a sofrer uma pressão antropogénica superior à dos sistemas costeiros abertos e afirma um esforço imediato para reduzir os resíduos plásticos e melhorar a gestão da eliminação de águas residuais na Ria Formosa. Os resultados desta investigação ajudariam a preencher as lacunas de conhecimento existentes e a definir novas zonas potenciais de acumulação de plástico em habitats costeiros chave para a vida selvagem marinha, mas é necessária investigação futura para melhor inferir o padrão de deposição de plástico nestes ecossistemas vitais.
- Environmental and nutritional parameters influencing the growth of Skeletonema cultures and optimization of the large-scale production in photobioreactorsPublication . Josenhans, Sarah; Raposo, Sara; Pereira, HugoMicroalgae have a large variety of applications and their biomass can be produced in a sustainable way. The diatom genus Skeletonema comprises a unique biochemical composition and is already widely used in the cultivation of shrimps and molluscs. The biomass of Skeletonema strains is rich in essential biomolecules, including fucoxanthin and polyunsaturated fatty acids and hold a high market demand. However, the large-scale production of this species is still challenging and needs to be optimised. In this context, different trials were conducted from lab- to industrial-scale and the growth of Skeletonema sp. cultures was observed and evaluated. In the laboratory, using Algem® photobioreactors (PBRs), obtained results revealed that autumn conditions are favourable over winter conditions, and cultures with lower inoculum concentrations show a higher specific growth rate. In addition, an initial silicate concentration of at least 0.11 mM favours the growth of the culture and the species growth is tolerant to pH values within 7.0 to 8.5. After the lab-scale optimization, cultures were successfully scaled-up under outdoor conditions, using flat panel PBRs of 100 - 1000 L and later to tubular PBRs up to 19000 L. In the production PBRs, it was found that nutrient starvation impairs the physiological state of cultures and diluted cultures suffer from photoinhibition by radiation maxima of 1500 μmol m-² s-1. A maximal daily growth rate of 0.331 d-1 was observed in a tubular PBR, exposed to an average radiation and temperature of 521 μmol m-² s-1 and 15.24 °C, respectively. The average macronutrient composition of Skeletonema sp. biomass as percentage of dry weight was 20.88 % carbohydrates, 31.52 % proteins and 18.14 % lipids. Overall, the lab-scale optimization and large-scale production of Skeletonema was successfully achieved and the biochemical composition of the biomass seems favourable for the nutrition of aquaculture organisms.
- Recreational shore angling in the south and southwest coast of mainland PortugalPublication . Pontes, João Carlos Oliveira; Erzini, Karim; Rangel, MafaldaAll fishing-related activities impact exploited ecosystems, which is underestimated by fisheries statistics that rely only on commercial fisheries information. Collection of recreational fishing data is mandatory under the EU Data Collection Framework (DCF, EC 199/2008), and will provide reliable, enabling the integration of catch estimates from commercial and recreational fisheries for stock assessments. Nevertheless, and despite the obligation of data collection on recreational fisheries, there is still the lack of up-to-date scientific information to support management. This studied aimed to characterize shore-based marine recreational fishing (MRF) in the south and southwest coast of Portugal (from Setúbal to V.R.S. António), promoting a systematic collection of data to ensure a solid scientific basis to implement adequate measures adjusted to the reality. Data collection was undertaken trough roving creel surveys using face-to-face questionnaires (in a digital Android system). The methodology implied a comprehensive sampling strategy in which the coastline was divided into 5 km sections considering the two Territorial Units for Statistical Purposes (NUTS II) in the study. A total of 403 shore angers were approached, resulting in 349 valid questionnaires (response rate of 87%). The studied population is constituted mainly by male individuals, of a wide range of age distribution, more common between 41 and 70 years old, with a high experience in the recreational activity. Sportfishing is not very popular among the surveyed anglers. The generically low educational level and the low monthly incomes are common for both regions of study, being most of the angler’s resident in the nearby region where the interview was developed and were fishing either alone or with their families/friends in equal proportion. The activity has his fishing effort peak during the Spring and Summer months, despite most of the surveyed anglers referred fishing during the entire year. The great majority of the anglers referred to know and to be reasonably satisfied with the current legislation and management measures. Nevertheless, a steady decay in the abundance of marine resources has been noticed and pollution and commercial fishing were pointed out as the main causes. A total of 856 individuals were caught, from 33 different species, with a total weight of 274.76 kg. The most important targeted species were the white seabream (Diplodus sargus) both in number and weight (N=365; W=86.07 kg), followed by the gilthead seabream (Sparus aurata) with 97 individuals caught that weighed72.93 kg and the spotted seabass (Dicentrarchus punctatus) with 106 individuals caught weighing 22.37 kg. The Sparidae family (Diplodus spp.) importance must be emphasized corresponding to 65.62% of the total catch. An annual harvest of 1992.48 tons of fish was estimated for shore-based marine recreational anglers of the Alentejo and the Algarve during 2018. The sargo breams (Diplodus spp.) are the most relevant catch species/group of species with 463.81tons, followed by the European seabass (Dicentrarchus labrax) with an estimated annual total catch of 116.40 tons, and the spotted seabass (Dicentrarchus punctatus) with 82.88 tons of fish. The economic revenue of the shore-based activity in the regions of Alentejo and Algarve, only regarding the direct expenses, was estimated to be 1.67 million euros. To ensure adequate management of the aquatic resources, it is crucial that studies like this continue being carried on a periodical basis, providing information that can serve as a baseline to support the current management measures.