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Bulletin de veille du réseau d'écotoxicologie terrestre et aquatique N°84
No full textINRAE, réseau ECOTOX → A paraîtreBulletin de veill
Biofouling in milli-labyrinth channels of drip irrigation systems using reclaimed wastewater: A review of optical methods and numerical modelling
No full textInternational audienceDrip irrigation systems are known for their high water-use efficiency due to the combination of using milli-labyrinth channels to optimise flow distribution and reusing reclaimed wastewater. However, clogging andbiofouling remain significant challenges that affect system performance and lifespan. This review provides acomprehensive overview of biofouling in drip irrigation systems, with a focus on how hydrodynamic conditionsand nutrient availability in reclaimed wastewater influence the attachment, growth, detachment, and decayof biofilm. The ability of advanced optical techniques, including particle tracking velocimetry, industrialcomputed tomography, and optical coherence tomography to visualise, measure, and analyse biofoulingprocesses in drip irrigation systems is discussed, along with their strengths and limitations. Additionally, theability of current biofilm modelling approaches, including both continuum and discrete methods, to simulatenutrient transport, microbial activity, and biofilm–fluid interactions are discussed. By combining insights fromexperimental data and computational models, this review also identifies key research gaps and presents a newframework for applying biofilm modelling to drip irrigation systems. Future research directions are suggestedto improve our understanding of drip irrigation biofouling and to predict it, to optimise emitter design, andincrease the overall reliability and sustainability of drip irrigation system
On the problem of minimizing the epidemic final size for SIR model by social distancing
No full textInternational audienceWe revisit the problem of minimizing the epidemic final size in the SIR model through social distancing of bounded intensity. In the existing literature, this problem has been considered imposing a priori interval structure on the time period when interventions are enforced. We show that when considering the more general class of controls with an L1 constraint on the confinement effort that reduces the infection rate, the support of the optimal control is still a single time interval. This shows that, for this problem, there is no benefit in splitting interventions on several disjoint time periods. However, if the infection rate is known beforehand to change with time once from one value to another one, then we show that the optimal solution could consist in splitting the interventions in at most two disjoint time periods
Monitoring tropical forests with light drones: ensuring spatial and temporal consistency in stereophotogrammetric products
No full textInternational audienceThis study benefited from an "Investissement d'Avenir" grant managed by the Agence Nationale de la Recherche (CEBA, ref. ANR-10-LABX-25-01), via project PHENOBS. We also acknowledge the support of the UE Biodiversa+ BiodivMon program (Project Coforfunc). We are thankful to Ilona Clocher, Jean-Louis Smock, Jean-Yves Goret, Florian Jeanne and Julien Engel for their help with drone data acquisition and/or processing. Access to the Paracou site and infrastructure (https://paracou.cirad.fr) was granted by CIRAD/Ecofog, and we thank Géraldine Derroire and all Phenobs project participants. We are grateful to Raphaël Pélissier for helping in the initial shaping of the Phenobs project and for his continued support
Plant conservation in a changing Mediterranean world
No full textInternational audienceSocietal Impact Statement The Mediterranean is one of five climatic regions on the planet characterised by a prolonged summer drought, exceptional plant diversity and high rates of endemism. We provide a framework to link the ecology of plant species conservation in the context of rapid and extreme climate deregulation to a philosophical typology of temporal attitudes (i.e., past, present and future). We argue that we must go beyond the historical heritage approach to embrace conservation action in a changing world. We review pragmatic and original ways to deepen social awareness for plant conservation, aligned with the three temporal themes. It is time to bring plants to the forefront of conservation action. Summary In this Thomas Review, we provide a structure that links ecological science of plant species conservation to a philosophical typology of temporal attitudes of scientists, i.e. ways of considering the inscription of one's action in time, with a preference for a temporal dimension in the past, the present or the future. We developed this framework to illustrate original ways of deepening social awareness for plant conservation. In section 1, we widen ecological and evolutionary foundations for plant conservation based on the historical floristic heritage to embrace the need to protect species at their range limits and the need to monitor the effects of extreme climate events. The processes that shape diversity and adaptation are central to this approach. Section 2 describes three temporal attitudes associated with the above three conservation themes. The remembrance attitude is characterised by its interest in the long‐term history of plant diversity. The anticipation attitude relies on climate scenarios and expected species distribution changes. Finally, a prudent attitude consists of making regular observations of ongoing change that relies on an iterative temporality of a continually renewed present. In section 3, we illustrate pragmatic and original ways to deepen social awareness for plant conservation in line with the three temporal themes. We conclude with a comment on the uncertainties surrounding conservation science and the need for confidence to act locally.El Mediterráneo es una de las cinco regiones climáticas del planeta caracterizadas por una prolongada sequía estival, una diversidad vegetal excepcional y altos índices de endemismo. En un contexto de desregulación climática acelerada y extrema, proponemos un marco para vincular la ecología de la conservación de especies vegetales con una tipología filosófica de actitudes temporales (pasado, presente y futuro). Sostenemos que es necesario superar un enfoque rígido centrado en el patrimonio natural y estructurar acciones de conservación adecuadas a un mundo en transformación. Examinamos medios pragmáticos y originales para fortalecer la concientización social sobre la conservación de las plantas en relación con estas tres dimensiones temporales. Ha llegado el momento de situar a las plantas en el centro de las estrategias de conservación.La Méditerranée est l'une des cinq régions climatiques de la planète caractérisées par une sécheresse estivale prolongée, une diversité végétale exceptionnelle et des taux élevés d'endémisme. Dans un contexte de dérégulation climatique accélérée et extrême, nous proposons un cadre pour relier l'écologie de la conservation des espèces végétales, à une typologie philosophique des attitudes temporelles (passé, présent et futur). Nous défendons l'idée qu'il faut dépasser une approche figée du patrimoine naturel et structurer des actions de conservation dans un monde en mutation. Nous passons en revue des moyens pragmatiques et originaux de renforcer la sensibilisation sociale à la conservation des plantes, en lien avec ces trois dimensions temporelles. Le moment est venu de mettre les plantes au cœur des stratégies de conservation.Il Mediterraneo è una delle cinque regioni climatiche del pianeta caratterizzate da una siccità estiva prolungata, un'eccezionale diversità vegetale e alti tassi di endemismo. In un contesto di sregolamento climatico, rapido ed estremo, proponiamo un quadro per collegare l'ecologia della conservazione delle specie vegetali a una tipologia filosofica delle attitudini temporali (passato, presente e futuro). Sosteniamo che occorre superare un approccio statico al patrimonio naturale e strutturare azioni di conservazione in un mondo in trasformazione. Esaminiamo modalità pragmatiche e originali per rafforzare la consapevolezza sociale sulla conservazione delle piante, in relazione a queste tre dimensioni temporali. È giunto il momento di mettere le piante al centro delle strategie di conservazione
First evidence of deleterious effect of pesticide mixture on health status in semi-captive grey partridges
No full textInternational audiencePesticides are mainly used in agroecosystems to control pests. Due to their limited specificity, the resulting widespread contamination may cause unintended effects on non-target organisms that use these habitats. While increasing attention is paid to the relationship between single substances and phenotype on non-target species, their combined impacts are still largely unknown. Since interactions between pesticides may also impact organisms' health, studying them as complex mixtures is the more realistic approach. Here, we present the first experimental study testing the relationship between an environmentally relevant pesticide mixture and health biomarkers on a farmland avian non-target model. To do so, we used 40 semi-captive grey partridges (Perdix perdix) fed for five months with conventional grains. Their plant protection product (PPP) load (i.e., the number of PPPs, the total sum of scaled pesticide concentrations and the total toxicity index) in blood and proxies of health status (evaluated using behavioral and physiological features) were monitored at the end of the exposure period. We demonstrated, for the first time, concerning correlations between PPP load indexes and bird healthrelated features (physical activity, flight initiation distance, eye ring redness and acetylcholinesterase activity). Overall, we highlighted the urgent need to consider environmentally-relevant PPP mixture when biomonitoring non-target vertebrates in ecotoxicological studies.</div
Ecological and management drivers of pest regulation via multitrophic pathways in tropical insular agroecosystems
No full textInternational audienceHighlights: • In La Réunion agroecosystems, field vegetation diversity boosts arthropod diversity. • Crop pests and damage decrease with increasing natural enemy diversity. • Pest regulation service benefits from field non-crop vegetation diversity. • Management and landscape factors also affect trophic cascades. • Vegetation diversity effects can outweigh management and landscape factors.Abstract: Natural pest regulation services provided by arthropod natural enemies are a cornerstone of ecological intensification. While vegetation diversification is known to support natural enemy communities, its relative contribution and interactions with other drivers for pest regulation services remains unclear, especially in dynamic and diversified smallholder agroecosystems under the tropics. In this study, we investigate how crop and non-crop field vegetation diversity, farming practices, climatic and landscape parameters jointly shape arthropod community structure and their services in the aerial and ground strata in tropical market gardening systems on La Réunion Island. We surveyed 22 open-field market gardening systems during two seasons. Using a multitrophic, piecewise structural equation modeling approach, we assessed direct and indirect cascading effects of local and landscape factors on arthropod diversity and pest regulation services. Results show that in aerial communities, non-crop vegetation richness generated a positive bottom-up trophic cascade. It enhanced herbivore diversity which, in turn, increased natural enemy richness, ultimately reducing pest abundance and crop damage, particularly during the dry season. In contrast, insecticide use suppressed natural enemy richness and reduced the effectiveness of pest regulation. Ground-dwelling communities were more strongly influenced by landscape fragmentation, semi-natural habitat cover, and temperature, with less evidence for structured trophic cascades. Overall, beneficial cascading effects of vegetation on pest regulation services in above-ground communities may outweigh the impacts of other management and landscape drivers. These findings underscore the potential of promoting vegetation diversity and reducing pesticide use as key strategies for enhancing natural pest regulation in tropical smallholder agroecosystems
Integrating problem structuring methods with formal design theory: collective water management policy design in Tunisia
No full textInternational audienceGroundwater management, especially in Mediterranean regions such as Tunisia, is challenging due to diverse stakeholder interests and the arid climate, which makes the sustainability of water resources extremely difficult. This paper proposes an innovative approach to the design of decision and policy alternatives by combining Problem Structuring Methods (PSMs) and the participatory tool based on the Concept-Knowledge (C-K) theory, named Policy-Knowledge, Concepts, Proposals (P-KCP). In a multi-methodological perspective, using Cognitive Maps and Value Trees in combination with P-KCP, the study aims to innovatively generate alternatives to address the sustainability issue of the case study, namely collective groundwater management. The paper provides a practical and adaptable guide to fostering innovation for policy design and generation of alternatives. By bridging decision theory and design theory, the study addresses the methodological gap in alternatives generation and highlights the role of C-K theory for supporting innovative design processes. Integrating PSMs and C-K theory, the multi-methodology advocates participatory approaches to address complex sustainability challenges, provides an adaptable, replicable tool, and encourages the creation of unconventional solutions. Ultimately, this paper offers new collective practices for groundwater management, expanding the set of alternatives through the integration of PSMs and C-K theory and reflecting on the applied multi-methodology
Influence of cover crops and their traits on the yield of main annual crops grown in tropical and subtropical environments - A meta-analysis
No full textSource Agritrop Cirad (https://agritrop.cirad.fr/615232/) * Autres projets (id;sigle;titre): ;TAZCO2;(BEN) Transition Agroécologique des Zones Cotonnières du Bénin//International audienceContext or problem: The sustainability of agriculture in tropical regions is threatened by climate change, soil degradation, and food insecurity. Crop diversification through growing cover crops is a promising strategy to mitigate these problems. However, their effects in rotation and as intercrops has not been comprehensibly assessed in the tropics, considering cultural practices, edapho-climatic conditions, and the functional traits of these cover crops. This study aims to conduct a comprehensive meta-analysis to simultaneously analyze, in rotation and intercropping systems, the effect of cover crops and their traits on the yield of main annual crops grown in tropical and subtropical regions. Methods: A meta-analysis was conducted based on 1788 field observations from 191 articles covering 29 tropical and subtropical countries and regions. The analysis accounted for both rotation and intercropping systems, while considering the variability in cultural practices, edapho-climatic conditions, and traits of cover crops. Results: The results showed that the cover crops increased yields of cereals, legumes, and fiber crops by 25 % in rotation and by 7 % in intercrops compared to monocrops. These effects varied greatly depending on the context. In rotation, yield gains were enhanced by crop residue incorporation, nitrogen application, bimodal tropical climates compared to unimodal ones, and altitude. In intercrops, positive effects were associated with the use of Fabaceae as cover crops, staggered sowing, altitude, temperature, and subtropical climates and volcanic soils (Andosols). Yield responses varied depending on the annual crop: in rotation, maize (290 %), soybeans (300 %), and cotton (240 %), relative yield gains were observed in low-yielding environments, while in intercrops only maize (360 %) showed gains under these conditions, and rice (- 30 %) suffered a decline. Analysis of cover crop traits revealed that in rotation systems, aboveground cover crops biomass, root diameter and root density explained part of the relative yield variability and were positively associated with relative yield. In intercrops, cover crops aboveground nitrogen mass was explanatory of annual crop yield. Conclusions: Fabaceae cover crops tend to perform better in intercropping, particularly in subtropical climates and in Andosols. In tropical crop rotations, conserving cover crop residues improves yields, further enhanced by nitrogen fertilization. Cover crops are particularly beneficial in low-yield contexts. Furthermore, the traits of cover crops are insufficiently documented, and their explanatory power remains limited, making the effects of cover crops on annual crop yields unclear. This highlights the importance of conducting further research in this area to gather additional evidence
Discrete numerical analysis of cohesive granular flow in a thin rotating drum: Flow regimes and cohesion estimation
No full textInternational audienceIn this study, we investigate the rheological behavior of cohesive granular flows within a rotating drum geometry using discrete element method (DEM) simulations. By systematically varying particle size, cohesion, and stiffness, we identify the emergence of distinct flow regimes-consistent with prior experimental observations. While the transitions between these regimes are primarily governed by cohesion, particle stiffness is also shown to significantly influence flow dynamics.To interpret the numerical results, we employ a dimensional analysis rooted in the physics of adhesive particle collisions. This analysis provides a conceptual framework for the remainder of the paper, which explores how "upscaled" discrete simulations can replicate experimental findings and help infer interparticle contact properties such as the adhesive surface energy. Notably, we use it to examine rotating drum experiments involving a unique class of granular materials, ice powders, which holds particular relevance in planetary science applications, and which flowability was shown to be strongly temperature-dependent