Effects of various configurations of vertical slot fishways on fish behaviour in an experimental flume

The knowledge of fish behaviour within vertical slot fishways is limited. This paper describes fish progression through five pools of the 1:4 scale vertical slot fishway of the University of Poitiers (France). Fish behaviour is studied by video monitoring in the third pool of the model. The results are analyzed comparing the number of fish passages between the pools, the stabling zones used by fish in the monitoring pool during their progression and fish trajectories. Comparison of four different pool configurations is performed to estimate the effect of geometric variations on the upstream migration efficiency

Plan de sauvegarde de l'anguille. Quelles solutions pour optimiser la conception et la gestion des ouvrages ?

Hier encore très répandue dans plupart des eaux douces d’Europe, l'anguille européenne connaît une régression rapide depuis les années 1970-1980. Les causes de ce déclin brutal, qui menace désormais la pérennité de l’espèce, sont pour l'essentiel connues : prélèvements par la pêche, dégradation de la qualité des eaux et des habitats, fragmentation des rivières sous l'effet des seuils et barrages et mortalités lors des passages dans les turbines hydroélectriques. Pour répondre aux objectifs de restauration des stocks fixés par l'Union européenne, la France s'est engagée dans un plan de gestion visant à agir sur chacun des facteurs de déclin de l'espèce. Sur le volet «ouvrages», le Ministère en charge de Développement durable a initié un programme de recherche & développement multi-partenarial, réunissant l'Ademe, l'Onema et cinq acteurs français de l’hydoéléctricité : Compagnie Nationale du Rhône, EDF, France Hydro Électricité, GDF Suez, Société hydroélectrique du Midi. Résolument opérationnel, ce programme, encadré par un comité de pilotage rassemblant les acteurs précédemment cités et placé sous l'autorité du MEDDE, s'est traduit par la mise au point et le test de solutions techniques en vue d’une mise en oeuvre directe sur les territoires. L'ensemble de ces acquis ont été présentés lors d’un colloque les 28 et 29 novembre 2011 qui a rassemblé près de 160 personnes : scientifiques, gestionnaires de l’eau, associations, producteurs d’hydroélectricité

Management plan to save the eel. Optimising the design and management of installations

The European eel was until recently an abundant species in most European freshwaters, but its numbers have fallen sharply since the 1970s and 1980s. The causes of the rapid decline, which now threatens the very existence of the species, are clear for the most part and include fishing, poor quality of water and habitats, fragmentation of rivers by weirs and dams, and death in hydroelectric turbines. To meet the restocking goals set by the European Union (EU), France has initiated a management plan addressing each of the factors responsible for the decline of the species. Concerning river obstacles and turbines, the Ecology ministry launched an R&D programme bringing together a number of partners, including Ademe, Onema and five hydroelectric companies, namely Compagnie nationale du Rhône, EDF, France Hydro Electricité, GDF Suez and Société hydroélectrique du Midi. The programme, managed by a steering committee comprising the partners mentioned above and placed under the responsibility of the Ecology ministry, targeted a number of operational goals that resulted in the development and testing of technical solutions designed for rapid implementation in the field. All programme results were presented on 28 and 29 November 2011 at the feedback symposium which brought together 160 persons, including researchers, water managers, associations and hydroelectric companies

A unique spinodal region in asymmetric nuclear matter

Asymmetric nuclear matter at sub-saturation densities is shown to present only one type of instabilities. The associated order parameter is dominated by the isoscalar density and so the transition is of liquid-gas type. The instability goes in the direction of a restoration of the isospin symmetry leading to a fractionation phenomenon. These conclusions are model independent since they can be related to the general form of the asymmetry energy. They are illustrated using density functional approaches.Comment: 4 pages, 5 figures, to appear in Phys. Rev.

An indicator to characterize hydrological alteration due to hydropeaking

Hydropeaking by hydroelectric facilities generates sudden changes in river flows and can affect the composition, abundance and structure of fish and invertebrate populations over long distances. To assess the level of hydrological alteration, as a factor of risk of biological impacts, a synthetic indicator was developed. Based on the analysis of 97 hydrometric stations and 1 575 years of unaltered flow data, rates of change in flow were calculated. Formulas representing the fastest natural variations, depending on the mean stream flow, the type of variation (increase or decrease) and the range of variation were established. Based on the analysis of 80 hydrometric stations and 491 years of flow data affected by hydropeaking, a method was developed to identify hydropeaks, essentially defined as variations with a rate of change greater than the maximum natural value computed using the formulas. A synthetic indicator differentiating five levels of hydrological alteration was developed using linear discriminant analysis based on five parameters characterizing hydropeaking regimes. Examples show that this indicator is sensitive to changes in the management of hydroelectric facilities and provides information on the spatial and temporal evolutions in hydropeaking regimes, including the progressive attenuation during downstream propagation

Control of turbulent flow in vertical slot fishways for the migration of small fish species

The improvement of devices that allow the upstream migration of fishes through engineering constructions or natural obstructions in rivers is now a real priority to maintain the biodiversity. Vertical slot fishways are commonly used and are very effective in ensuring unhindered passage of the species of large size fishes

What do we know to evaluate the health of brown trout (Salmo trutta) populations?

peer reviewedThe renewed emphasis on the concept of the health of ecosystems highlights society’s interest in taking measures to protect environments transformed by human activity. The criteria used for evaluating the health of fish population are rarely discussed within the scientific community. The exercise proposed here aimed to discuss these for the brown trout (Salmo trutta), a flagship species from the freshwater fish community typical from headwaters of watercourses which represent most of the French hydrographic network. This initiative aimed to gather the ideas of a limited number of experts on the function of these populations and on the criteria for evaluating their function. The main key parameters were identified and organised into a hierarchical framework for each development stage. A consensus emerged on the fact that in the current stage of knowledge, the diagnosis can be established based on the analysis of abiotic parameters crucial for the biology and, with more difficulty, on the analysis of biotic parameters. For all the development stages, the identified parameters are linked to habitat (substrate, stream flow, temperature and water quality), hydrology and connectivity. Further knowledge must be acquired in order to be able to measure the biological criteria. That implies to reinforce longterm biological monitoring and research to understand the variability in biological parameters, the relevant spatiotemporal scales and the functional processes

Hydropeaking impacts on the Lez river and studies to define mitigation measures

Hydropeaking impacts on the Lez river and studies to define mitigation measure

As redes sociais na internet e suas apropriações por jovens brasileiros e portugueses em idade escolar

O fenômeno das redes sociais on-line é marcante na atual fase da internet 2.0, tendo crescido vertiginosamente, a partir do ano 2005, com a adesão majoritária de jovens, que as acessam por computadores fixos e móveis, em plataformas dos mais variados tipos. Por meio delas, trocam mensagens e compartilham conteúdos os mais diversos. Diante desse cenário, com base em duas pesquisas convergentes, pretende-se discutir os usos e as apropriações das redes sociais on-line por jovens alunos do ensino fundamental e médio e destacar os pontos mais pertinentes da atual fase da internet nos contextos pessoal, familiar e escolar. Foram aplicados questionários, inspirados em modelo de pesquisa elaborado na Itália, a 404 alunos brasileiros de oito escolas no Rio de Janeiro e a 549 alunos portugueses de 11 escolas na região portuguesa de Castelo Branco. Com essa rica empiria, verificou-se em que pontos os jovens se aproximam dos ideais de uma nova subjetividade (o leitor imerso nas novas mídias) e de um jovem naturalmente afeito aos suportes digitais (o nativo digital).The phenomenon of online social networks has been remarkable in the current phase of internet 2.0 and has grown rapidly from the year 2005, with the majority membership of young people, who access the social networks from desktops and mobile platforms of all kinds. Using these platforms, they exchange messages and share various contents. Given this scenario, based on two converging researches, this paper discusses the uses and appropriations of online social networks by students of elementary school and high school. Also, it highlights the most relevant points in the current phase of the internet in relation to personal, family and school contexts. Inspired by a research model developed in Italy, 404 questionnaires were applied to Brazilian students from eight schools in Rio de Janeiro and 549 Portuguese students from 11 schools in the Portuguese region of Castelo Branco. With this comprehensive database, we could verify at which points the youth approaches the ideals of a new subjectivity (the reader immersed in new medias) and a youngster naturally used to digital media (the digital native).info:eu-repo/semantics/publishedVersio

Challenges for the Development of New Non-Toxic Antifouling Solutions

Marine biofouling is of major economic concern to all marine industries. The shipping trade is particularly alert to the development of new antifouling (AF) strategies, especially green AF paint as international regulations regarding the environmental impact of the compounds actually incorporated into the formulations are becoming more and more strict. It is also recognised that vessels play an extensive role in invasive species propagation as ballast waters transport potentially threatening larvae. It is then crucial to develop new AF solutions combining advances in marine chemistry and topography, in addition to a knowledge of marine biofoulers, with respect to the marine environment. This review presents the recent research progress made in the field of new non-toxic AF solutions (new microtexturing of surfaces, foul-release coatings, and with a special emphasis on marine natural antifoulants) as well as the perspectives for future research directions