Browsing by Author "Fernandes, Francisco"
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- Certificação sísmica das construções e perigosidade sísmica em PortugalPublication . Costa, Aníbal; Azevedo, João; Coelho, Ema; Fernandes, Francisco; Guerreiro, Luís M. C.; Carvalho, Alexandra; Matias, Luis; Oliveira, Daniel; Romão, Xavier; Estêvão, João Manuel CarvalhoA análise dos efeitos dos sismos nas construções permite evidenciar, novamente, que as estruturas construídas de acordo com as modernas regulamentações para o dimensionamento sísmico de estruturas se comportam bem, sendo naquelas que não obedecem a estas regulamentações que se verificam os maiores danos e que originam um grande número de mortes. A necessidade de garantir que todas as novas estruturas, ou aquelas que vierem a ser reabilitadas ou reconstruídas, cumpram as prescrições previstas na regulamentação para as dotar de bom comportamento sísmico deve, assim, constituir uma preocupação essencial das sociedades que habitam zonas em que exista um significativo risco sísmico, como é caso de Portugal. Neste contexto, a Sociedade Portuguesa de Engenharia Sísmica (SPES) tem ao longo dos últimos anos vindo a desenvolver campanhas para sensibilizar os poderes políticos para a necessidade de certificar as construções existentes. Nesse sentido a SPES está a desenvolver metodologias para brevemente apresentar uma proposta para a certificação do comportamento sísmico das construções onde serão identificados os procedimentos que devem ser adotados para a certificação dos edifícios existentes. Acrescente-se, ainda, uma outra preocupação da SPES, relacionada com os diferentes mapas de perigosidade sísmica para Portugal continental que têm resultado de vários projetos nacionais e internacionais, e que traduzem níveis de perigosidade sísmica muito diferentes para algumas regiões do território português, particularmente para o sul de Portugal. A SPES, espelhando a inquietude existente na comunidade científica, considerou urgente e promoveu a realização de um estudo criterioso acerca das opções tomadas, nos diferentes estudos, de forma a tentar perceber os fatores que mais contribuíram para as diferenças evidenciadas.
- Genes left behind: Climate change threatens cryptic genetic diversity in the canopy-forming seaweed bifurcaria bifurcataPublication . Neiva, J.; Assis, J.; Coelho, Nelson; Fernandes, Francisco; Pearson, Gareth; Serrao, Ester A.The global redistribution of biodiversity will intensify in the coming decades of climate change, making projections of species range shifts and of associated genetic losses important components of conservation planning. Highly-structured marine species, notably brown seaweeds, often harbor unique genetic variation at warmer low-latitude rear edges and thus are of particular concern. Here, a combination of Ecological Niche Models (ENMs) and molecular data is used to forecast the potential near-future impacts of climate change for a warm-temperate, canopy forming seaweed, Bifurcaria bifurcata. ENMs for B. bifurcata were developed using marine and terrestrial climatic variables, and its range projected for 2040-50 and 2090-2100 under two greenhouse emission scenarios. Geographical patterns of genetic diversity were assessed by screening 18 populations spawning the entire distribution for two organelle genes and 6 microsatellite markers. The southern limit of B. bifurcata was predicted to shift northwards to central Morocco by the mid-century. By 2090-2100, depending on the emission scenario, it could either retreat further north to western Iberia or be relocated back to Western Sahara. At the opposing margin, B. bifurcata was predicted to expand its range to Scotland or even Norway. Microsatellite diversity and endemism were highest in Morocco, where a unique and very restricted lineage was also identified. Our results imply that B. bifurcata will maintain a relatively broad latitudinal distribution. Although its persistence is not threatened, the predicted extirpation of a unique southern lineage or even the entire Moroccan diversity hotspot will erase a rich evolutionary legacy and shrink global diversity to current (low) European levels. NW Africa and similarly understudied southern regions should receive added attention if expected range changes and diversity loss of warm-temperate species is not to occur unnoticed.
- Habitat continuity and stepping-stone oceanographic distances explain population genetic connectivity of the brown alga Cystoseira amentaceaPublication . Buonomo, Roberto; Assis, J.; Fernandes, Francisco; Engelen, Aschwin H.; Airoldi, Laura; Serrao, Ester A.Effective predictive and management approaches for species occurring in a metapopulation structure require good understanding of interpopulation connectivity. In this study, we ask whether population genetic structure of marine species with fragmented distributions can be predicted by stepping-stone oceanographic transport and habitat continuity, using as model an ecosystem-structuring brown alga, Cystoseira amentacea var. stricta. To answer this question, we analysed the genetic structure and estimated the connectivity of populations along discontinuous rocky habitat patches in southern Italy, using microsatellite markers at multiple scales. In addition, we modelled the effect of rocky habitat continuity and ocean circulation on gene flow by simulating Lagrangian particle dispersal based on ocean surface currents allowing multigenerational stepping-stone dynamics. Populations were highly differentiated, at scales from few metres up to thousands of kilometres. The best possible model fit to explain the genetic results combined current direction, rocky habitat extension and distance along the coast among rocky sites. We conclude that a combination of variable suitable habitat and oceanographic transport is a useful predictor of genetic structure. This relationship provides insight into the mechanisms of dispersal and the role of life-history traits. Our results highlight the importance of spatially explicit modelling of stepping-stone dynamics and oceanographic directional transport coupled with habitat suitability, to better describe and predict marine population structure and differentiation. This study also suggests the appropriate spatial scales for the conservation, restoration and management of species that are increasingly affected by habitat modifications.