Strong Zonation of Benthic Communities Across a Tidal Freshwater Height Gradient

Trade-offs associated with environmental gradients generate patterns of diversity and govern community organisation in a landscape. In freshwaters, benthic community structure is driven by trade-offs along generally orthogonal gradients of habitat permanence and predation—where ephemeral systems are physiologically harsh because of drying stress, but inhabitants are less likely to be under the intense predation pressure of more permanent waterbodies. However, in tidal freshwaters, these two stressors are compounding, and the trade-offs associated with them are decoupled. 2. We investigated benthic community structure in a tidal freshwater habitat. These communities experience a suite of conditions atypical for a freshwater habitat: twice-daily drying; and high predation pressure by mobile fishes. We compared benthic communities at three tidal heights (low, mid, high) and contrasted these with nearby non-tidal freshwaters that varied in their hydrology (permanent, temporary). 3. We found that communities were more strongly differentiated in tidal freshwater habitats than between permanent and temporary inland freshwaters, which was surprising given the high interconnectedness and condensed longitudinal scale of tidal habitats. The differentiation of communities in tidal habitats was probably driven by the combined gradients of desiccation risk at low tide and intense predation by fish at high tide—a combination of pressures that are novel for the evolutionary history of the regional freshwater invertebrate fauna. 4. Our study provides evidence that environmental gradients can produce stronger patterns of community zonation than would be predicted for habitats that are spatially contiguous and have little or no dispersal limitation. These results give insight into how communities might respond if drivers of community structure are altered or reorganised from their regional or evolutionary norms

Everyday vulnerabilities and ''social dispositions'' in the Malian Sahel, an indication for evaluating future adaptability to water crises?

International audienceSince the 1970s, precipitation in the Sahel has decreased and become very irregular, leading to widespread drought, whilst the human need for water has rapidly increased. A new ''dispositions''-based approach was adapted in order to analyse human interactions with environmental hazards and applied to the case of Hombori village in northeastern Mali. This article explores how the population and political stakeholders perceive, live with and respond to the increasing scarcity of water. It also explores how their current vulnerability and ability to cope with variations in available water resources indicate future adaptability to climate shocks. On the one hand, this research shows how the population copes with variations in water resource availability: the population's socio-spatial organisation explains the inhabitants' exposure to this problem and some of the factors affecting vulnerability, the elderly and women being the hardest hit. The water issue is generally managed on a ''day-to-day'' basis and considered a big problem only in the dry season, thus lowering any incentive for self-protection. The main two variables that could explain this kind of risk management are the conflicting local governance and current social rules. On the other hand, the discussion of results, based on a conceptual model of social responses, explains why these current ''social dispositions'' to cope with and even address the water scarcity issue do not guarantee future adaptability to climate change

Problematic gaming and quality of life in online competitive videogame players: Identification of motivational profiles.

Online competitive practice of video games has recently known a significant worldwide expansion. However, this practice can be associated to problematic use and deterioration of quality of life depending on multiple determinants, among which motivation is central. The purpose of this study was to identify motivational clusters and to compare them regarding quality of life, problematic use of video game, and personality traits. Participants (N = 256) in this cross-sectional study were recruited through specialized websites to complete self-reported questionnaires assessing motivation to play online (MOGQ), personality (BFI-Fr), quality of life (WHOQOL-BREF), and problematic gaming (IGD-Scale). A hierarchical clustering analysis and intergroup comparative analyses were conducted. Three motivational clusters were identified ("recreational", "competitive" and "escapers"). "Competitive" and "escapers" players reported higher IGD scores than the "recreational" players (p <.001). However, "escapers" players had lower psychological health scores (p <.001), were more neurotic (p <.001), and less extroverted (p <.001) than the others. Based on IGD scores, "competitive" and "escapers" players were considered as problematic albeit only "escapers" exhibited a functional impairment. Therefore, engaged and problematic players cannot be differentiated with IGD scores. IGD scores were insufficient to differentiate between players at risk of evolution toward pathological states (i.e., "escapers" players) and those whose strong engagement is not detrimental to their quality of life (i.e., "competitive" players). Consequently, considering both psychological health and motivation is necessary to assess the problematic nature of competitive videogame practice. Better definitions and assessment tools are essential in order to avoid over-diagnosis of non-pathological gaming behavior

Approche hydrodynamique de la microdistribution d'invertébrés benthiques en eau courante

La microdistribution des larves et nymphes de 3 espèces de simulies (Odagmia variegata, Odagmia obreptans et Simulium rupicolum) a été observée en divers cours d'eau pyrénéens. Ces espèces se rencontrent en présence de vitesses importantes qui, dans les ruisseaux étudiés, étaient présentes dans les zones à écoulement torrentiel. Nous ne les avons pas rencontrées dans les zones à écoulement général de type fluvial. Les pierres lisses et d'un diamètre supérieur à 10 cm environ sont les substrats les mieux colonisés. Les faces amont faiblement inclinées présentent les plus fortes densités larvaires. Dans les zones à fort courant, en présence d'un gradient longitudinal même réduit des vitesses, les larves se concentrent dans une étroite bande où les vitesses sont maximales. Le corps des larves est couché vers l'aval et subit les pulsations du courant. Les larves de simulies colonisent rapidement des canaux immergés dans un ruisseau (fig. 2) ; et par suite, les conditions hydrauliques locales peuvent être précisées aux endroits où se fixent les larves. En une même station, le débit variant dans le temps, le type d'écoulement peut passer du fluvial au torrentiel (fig. 3 et 4). Les profils des vitesses à la paroi, c'est-à-dire dans la zone où vivent les invertébrés, peuvent être déterminés en fonction de la rugosité apparente de la paroi (fig. 6). Les conditions d'existence d'un film laminaire (sous couche laminaire) dépendent de la vitesse du courant et de la dimension des aspérités (fig. 7 et 8). Pour une vitesse de courant donnée, les relations entre l'épaisseur δ du film laminaire et la dimension ε des aspérités déterminent les possibilités d'existence du film laminaire (fig. 8). La variation de l'épaisseur du film laminaire est représentée en fonction de la vitesse du courant dans un abaque (fig. 9) qui tient compte également des conditions imposées par la dimension des aspérités. Le film laminaire n'a qu'une influence réduite sur les conditions de vie des larves de simulies; la turbulence joue un rôle important sur ces conditions de vie

Bridging human and natural sciences in landscape research

Landscape issues are of interest in many disciplines, but they are seldom seen as an opportunity for interdisciplinary or transdisciplinary cooperation. This limits the ability to account for real world complexity. Bridging human and natural sciences intends to foster and coordinate communication about landscape-related issues - within academia and between science and society. The collection of papers in this special issue and the recommendations for future research are selected from the conference Multifunctional landscapes - interdisciplinary approaches to landscape research and aanagement in Roskilde, Denmark, 2000. The contributions all bear evidence of an integrating approach to landscape research, bridging human and natural sciences

Bridging human and natural sciences in landscape research

Landscape issues are of interest in many disciplines, but they are seldom seen as an opportunity for interdisciplinary or transdisciplinary cooperation. This limits the ability to account for real world complexity. Bridging human and natural sciences intends to foster and coordinate communication about landscape-related issues - within academia and between science and society. The collection of papers in this special issue and the recommendations for future research are selected from the conference Multifunctional landscapes - interdisciplinary approaches to landscape research and aanagement in Roskilde, Denmark, 2000. The contributions all bear evidence of an integrating approach to landscape research, bridging human and natural sciences

Les enjeux de recherche liés à la directive-cadre européenne sur l'eau

International audienceResearch needs for the implementation of the water European Framework Directive. We present the research needs required to implement the European Framework Directive forWater, involving a better understanding of the ecosystem dynamics, a better knowledge of groundwater bodies, strong efforts in ecotoxycology and a new approach in water economics.Nous présentons les enjeux de recherche suscités par la directive-cadre européenne sur l'eau : ils concernent la compréhension de la dynamique des écosystèmes, un approfondissement des connaissances relatives aux eaux souterraines, un important développement de l'écotoxicologie et une nouvelle approche de l'économie de l'eau

Les enjeux de recherche liés à la directive-cadre européenne sur l'eau

[Departement_IRSTEA]MA [TR1_IRSTEA]QSA / HYDRECOInternational audienceResearch needs for the implementation of the water European Framework Directive. We present the research needs required to implement the European Framework Directive forWater, involving a better understanding of the ecosystem dynamics, a better knowledge of groundwater bodies, strong efforts in ecotoxycology and a new approach in water economics.Nous présentons les enjeux de recherche suscités par la directive-cadre européenne sur l'eau : ils concernent la compréhension de la dynamique des écosystèmes, un approfondissement des connaissances relatives aux eaux souterraines, un important développement de l'écotoxicologie et une nouvelle approche de l'économie de l'eau