1,057 research outputs found

    Concentrations levels and effects of 17alpha-Ethinylestradiol in freshwater and marine waters and bivalves: a review

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    Pharmaceutical drugs are contaminants of emerging concern and are amongst the most frequent in the aquatic environment. Even though a vast literature indicate that pharmaceuticals exert negative impacts towards aquatic organisms, mainly in vertebrates, there is still limited information regarding the effects of these drugs in freshwater and marine bivalves. Marine bivalves have a high ecological and socio-economic value and are considered good bioindicator species in ecotoxicology and risk assessment programs. Furthermore, another lacking point on these studies is the absence of bioconcentration data, with no clear relationship between the concentration of drugs on tissue and the biological effects. 17alpha-ethinylestradiol (EE2) is a synthetic hormone with high estrogenic potency that was added to the Watch List adopted by the European Commission stating the priority substances to be monitored. Thus, this review summarizes the current knowledge on the concentration levels and effects of EE2 on freshwater and marine bivalves. The inclusion in the Watch List, the presence in freshwater and marine systems, and the impact exerted on aquatic biota, even at trace concentrations, justify the review devoted to this pharmaceutical drug. Globally the available studies found that EE2 induces individual and sub-individual (e.g. tissue, cellular, biochemical and molecular levels of biological organization) impacts in bivalves. Essentially, this estrogenic compound, even in trace concentrations, was found to have accumulated in wild and laboratory exposed bivalves. The most common effects reported were changes on the reproductive function and energy metabolism. The studies used in this review support keeping the EE2 on the Watch List and highlight the need to increase the number of monitorization studies since clear negative effects were exerted on bivalves by this drug.publishe

    Envolvimento académico : confronto de expectativas e comportamentos em universitários do 1º ano

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    No presente trabalho analisam-se as expectativas dos estudantes acerca do seu envolvimento em diversas dimensões associadas à vida académica, assim como os comportamentos vivenciados uns meses após essa entrada tomando as mesmas dimensões. A amostra considerada é formada por 314 estudantes do 1º ano de três agrupamentos de cursos (Ciências e Engenharia; Ciências Económicas; e Ciências Sociais e Humanas) da Universidade do Minho. Estes alunos responderam, no início do ano e a meados do 2º semestre, ao Questionário de Envolvimento Académico (QEA; Soares & Almeida, 2001) nas suas versões de expectativas (Versão A) e comportamentos (Versão B). Os resultados sugerem níveis elevados de expectativas iniciais dos es- tudantes no momento da sua entrada na Universidade, registando-se uma diminuição significativa de tais índices no segundo momento da avaliação, em particular nas subescalas de envolvimento institucional e de envolvimento vocacional. Algumas oscilações nos resultados foram encontradas tomando os alunos de acordo com o agrupamento do curso frequentado, com o género, os níveis escolares dos pais ou o facto de frequentarem ou não um curso de 1º opção.This paper analyses students’ initial expectations concerning personal investment in different domains of academic life, as well as behaviours some months later in those same dimensions. The sample included 314 first year students of the University of Minho from three graduations areas: science and engineering, economic sciences, and social sciences and humanities. A questionnaire of academic involvement (QEA; Soares & Almeida, 2001) was applied to students at entrance (expectations version) and at middle of first semester (behaviours version). Results suggest higher levels of initial expectations at the entrance in the university, and a significant decrease of those levels some months later, namely in the institutional and vocational subscales. Some significant changes have been found considering the domain and option of graduation studies, gender and academic level of parents.Fundação Calouste Gulbenkian - Programa de Apoio a Projectos de Pesquisa no Domínio Educativo (2001/04) - projecto “Transição, adaptação e sucesso académico de jovens no Ensino Superior

    The effect of temperature on Triclosan and Lead exposed mussels

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    Interest on the effects of emerging contaminants over aquatic organisms has increased in the last years. Nonetheless, the toxic action of classical natural and anthropogenically-driven metals has also to be monitored, especially because they reflect real environmental situations. For that, in the present study we focused on the effects on the marine mussel Mytilus galloprovincialis of the personal care product Triclosan (TCS) and Lead (Pb), as toxic metal, under separate and co-exposure situations at environmentally relevant concentrations: TCS (1 μg/L) and Pb (50 μg/L). The consideration of an additional factor such as an increase in ambient temperature was also included to provide a forecasted scenario of climate change: from the ambient temperature at actual conditions (17 °C) to a predicted warming situation (22 °C). Water chemical characterization and some physical properties and bioaccumulation of TCS and Pb in mussels at the end of the experiment (28 days) was considered. The parameters followed up comprise the energy related system production (electron transport system) and glycogen and protein reserves. Antioxidant enzymatic defences towards reactive oxygen species (ROS) and the consequences of ROS damage over endogenous lipids (LPO) and proteins (PC). Overall the results suggested only particular responses to chemical exposures at 17 °C whereas at 22 °C the detoxification machinery was set up and this prevented the occurrence of LPO. Nonetheless, PC formation occurred under Pb and TCS + Pb co-exposure at the highest temperature. Due to the complexity of the study: 4 chemical conditions, 2 temperatures and 10 biomarkers considered, a principal component ordination (PCO) analysis was included. The results of this integrative analysis confirmed a clear effect of the temperature, more responsiveness to drugs at 22 °C and in all likelihood due to Pb presence.publishe

    Comparative sensitivity of Crassostrea angulata and Crassostrea gigas embryo-larval development to As under varying salinity and temperature

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    Oysters are a diverse group of marine bivalves that inhabit coastal systems of the world's oceans, providing a varietyofecosystemservices,andrepresentamajorsocioeconomic resource.However,oysterreefshavebecome inevitably impacted from habitat destruction, overfishing, pollution and disease outbreaks that have pushed these structures to the break of extinction. In addition, the increased frequency of climate change related events promise to further challenge oyster species survival worldwide. Oysters' early embryonic development is likely the most vulnerable stage to climate change related stressors (e.g. salinity and temperature shifts) as well as to pollutants (e.g. arsenic), and therefore can represent the most important bottleneck that define populations' survival in a changing environment. In light of this, the present study aimed to assess two important oyster species, Crassostrea angulata and Crassostrea gigas embryo-larval development, under combinations of salinity (20, 26 and 33), temperature (20, 24 and 28°C) and arsenic (As) exposure(0,30,60,120,240,480,960and1920μg.AsL−1),toinferondifferentoysterspeciescapacitytocope with these environmental stressors under the eminent threat of climate change and increase of pollution worldwide. Results showed differences in each species range of salinity and temperature for successful embryonic development. For C angulata, embryo-larval development was successful at a narrower range of both salinity and temperature, compared to C. gigas. Overall, As induced higher toxicity to C. angulata embryos, with calculated EC50 values at least an order of magnitude lower than those calculated for C. gigas. The toxicity of As (measured as median effective concentration, EC50) showed to be influenced by both salinity and temperature in both species. Nonetheless, salinity had a greater influence on embryos' sensitivity to As. This pattern was mostly noticed for C. gigas, with lower salinity inducing higher sensitivity to As. Results were discussed considering the existing literature and suggest that C. angulata populations are likely to become more vulnerable under near future predictions for temperature rise, salinity shifts and pollution.publishe

    Engineering impacting social, economic and working environment

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    Engineers create, design and build, bringing solutions to problems and transforming the environment for betterment of life. Engineers are responsible for the development of science and technology once they design tools, systems and instruments that make possible the acquisition of knowledge in a vast amount of fields. Engineering is responsible for the deep transformation of human relations in the first decade of the 21st century, changing also education paradigms as well as business. A new era in working environment has started, which characteristics are peculiar due to new communications, mobility and globalization. These aspects lead to the fact that now it is also important to train engineers with tools that enable them to act in a working environment that demands a very flexible and innovative mind in order to be inserted in and to keep up with the work market. Knowledge in Basic Sciences, Basic Sciences of Engineering and Specifics of Engineering are fundamental for the training of an engineer. However, the insertion in labor market sometimes demands some practice or experience that should also be provided by the engineering schools. Taking this into account, the Engineering Education Research Team of COPEC – Science and Education Research Council has designed and is implementing a program for an engineering school which main goal is to prepare engineers for the future work market, the engineer for the future. The idea was born due to the very competitive environment that Engineering Schools are facing recently and the fact that fewer young students are choosing engineering as a career to pursue despite work market demand for engineers

    Population size and survivorship for juvenile lemon sharks (\u3cem\u3eNegaprion brevirostris\u3c/em\u3e) on their nursery grounds at a marine protected area in Brazil

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    Sharks face a number of obstacles for surviving their first several years of life and many species occupy nursery areas. Although estimates of survival, particularly for young age classes, are essential for assessing, monitoring and effectively managing animal populations, there have been relatively few calculations of survival within shark populations and even fewer estimates based on direct methods for sharks on their nursery grounds. We used tag-recapture methods to estimate the population size and survival of juvenile lemon sharks (Negaprion brevirostris) on their nursery grounds at Atol das Rocas, a marine protected area in Brazil. Sharks were sampled from1999 to 2003. Population size estimates ranged from 12 to 100 juvenile sharks and survival estimates ranged between 24-54% with a mean of 44.6% over the most robust sampling periods. The population of juvenile lemon sharks declined over the course of our study, whereas survival rates may have increased over the same time period. Even a modest level of fishing and removal of mature females in adjacent areas may dramatically affect small populations of sharks within a small and isolated nursery such as Atol das Rocas. The lower survival rates and population size at Atol das Rocas could be the result of differences in physical characteristics of this nursery in comparison to others used by lemon sharks in the northwestern Atlantic. Such comparatively lower populational parameters suggest that the population of young lemon sharks is fragile at the Atol das Rocas nursery

    Population size and survivorship for juvenile lemon sharks (\u3cem\u3eNegaprion brevirostris\u3c/em\u3e) on their nursery grounds at a marine protected area in Brazil

    Get PDF
    Sharks face a number of obstacles for surviving their first several years of life and many species occupy nursery areas. Although estimates of survival, particularly for young age classes, are essential for assessing, monitoring and effectively managing animal populations, there have been relatively few calculations of survival within shark populations and even fewer estimates based on direct methods for sharks on their nursery grounds. We used tag-recapture methods to estimate the population size and survival of juvenile lemon sharks (Negaprion brevirostris) on their nursery grounds at Atol das Rocas, a marine protected area in Brazil. Sharks were sampled from1999 to 2003. Population size estimates ranged from 12 to 100 juvenile sharks and survival estimates ranged between 24-54% with a mean of 44.6% over the most robust sampling periods. The population of juvenile lemon sharks declined over the course of our study, whereas survival rates may have increased over the same time period. Even a modest level of fishing and removal of mature females in adjacent areas may dramatically affect small populations of sharks within a small and isolated nursery such as Atol das Rocas. The lower survival rates and population size at Atol das Rocas could be the result of differences in physical characteristics of this nursery in comparison to others used by lemon sharks in the northwestern Atlantic. Such comparatively lower populational parameters suggest that the population of young lemon sharks is fragile at the Atol das Rocas nursery

    Are the effects induced by increased temperature enhanced in Mytilus galloprovincialis submitted to air exposure?

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    Intertidal mussel species are frequently exposed to changes of environmental parameters related to tidal regimes that include a multitude of stressors that they must avoid or tolerate by developing adaptive strategies. In particular, besides air exposure during low tides, intertidal mussels are also subjected to warming and, consequently, to higher risk of desiccation. However, scarce information is available regarding the responses of mussels to tidal regimes, particularly in the presence of other stressors such as increased temperature. Investigating the impacts of such combination of conditions will allow to understand the possible impacts that both factors interaction may generate to these intertidal organisms. To this end, the present study evaluated the impacts of different temperatures (18 ºC and 21 ºC) on Mytilus galloprovincialis when continuously submersed or exposed to a tidal regime for 14 days. Results showed that in mussels exposed to increased temperature under submersion conditions, the stress induced was enough to activate mussels’ antioxidant defenses (namely glutathione peroxidase, GPx), preventing oxidative damage (lipid peroxidation, LPO; protein carbonylation, PC). In mussels exposed to tides at control temperature, metabolic capacity increased (electron transport system activity, ETS), and GPx was induced, despite resulting in increased LPO levels. Moreover, the combination of tides and temperature increase led to a significant decrease of lipid (LIP) content, activation of antioxidant defenses (superoxide dismutase, SOD; GPx) and increase of oxidized glutathione (GSSG), despite these mechanisms were not sufficient to prevent increased cellular damage. Therefore, the combination of increased temperature and air exposure induced higher oxidative stress in mussels. These findings indicate that increasing global warming could be more impacting to intertidal organisms compared to organisms continuously submersed. Furthermore, our results indicate that air exposure can act as a confounding factor when assessing the impacts of different stressors in organisms living in coastal systemspublishe
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