Portail Hal-l'Institut Agro Rennes-Angers
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Le Changement Climatique en Bretagne, Bulletin du HCBC 2024 : Le littoral breton face aux défis climatiques
No full textHaut Conseil Breton sur le ClimatAprès deux années d’existence, le Haut Conseil Breton pour le Climat (HCBC) a trouvé son rythmede croisière et lancé ses principaux chantiers. Le premier Forum Climat et Territoires organisé à Lorienten juin 2023 a été un succès et celui qui se profile à Brest au mois de mai s’inscrit déjà dans le calendrierdes manifestations régionales incontournables sur la question du changement climatique. Le HCBCa également produit trois avis sur les politiques publiques régionales et sera prochainement doté d’unnouveau site web qui donnera plus de visibilité aux recherches sur le changement climatique en Bretagne.En 2023, le HCBC a participé à 80 évènements (conférences, tables rondes, articles de presse, ...) et permisde sensibiliser directement plus de 3000 personnes sur ces enjeux régionaux! Quatre groupes de travailsont désormais en place sur les questions de l’agriculture, des transformations sociales, des formationset du littoral. Ce dernier thème est un enjeu fondamental dans notre région tournée vers la mer. C’est doncle littoral, face aux défis du changement climatique (montée du niveau de la mer, érosion, acidification, …)qui constitue le dossier central de ce deuxième bulletin annuel du HCBC.L’année 2023 aura fait jeu égal avec 2022 en Bretagne en termes de température moyenne. Sil’été 2023 est resté dans les normes, des records de températures ont été battus en juin, septembreet octobre, montrant la diversité des formes que peut revêtir le changement climatique dans notre région:cœur de l’été plus intense comme en 2022 ou une saison chaude plus longue parce que plus précoce etplus tardive en 2023. Les tempêtes et les fortes pluies de l’automne sont venues rappeler la multiplicitédes aléas (et pas seulement les vagues de chaleur) auxquels nous serons confrontés à l’avenir.Pour faire face à tous ces changements, la mobilisation de tous les acteurs est plus que jamaisune impérieuse nécessité
Multigroup Latent Structural Equation Modeling An application to assess the stability of soil nitrifying comunities in agroforestry systems
No full textInternational audienc
GenAPoPop 1.0 : A user‐friendly software to analyse genetic diversity and structure from partially clonal and selfed autopolyploid organisms: Population genetic analyses of autopolyploids
No full textInternational audienceAutopolyploidy is quite common in most clades of eukaryotes. The emergence of sequence‐based genotyping methods with individual and marker tags now enables confident allele dosage, overcoming the main obstacle to the democratization of the population genetic approaches when studying ecology and evolution of autopolyploid populations and species. Reproductive modes, including clonality, selfing and allogamy, have deep consequences on the ecology and evolution of population and species. Analysing genetic diversity and its dynamics over generations is one efficient way to infer the relative importance of clonality, selfing and allogamy in populations. GenAPoPop is a user‐friendly solution to compute the specific corpus of population genetic indices, including indices about genotypic diversity, needed to analyse partially clonal, selfed and allogamous polysomic populations genotyped with confident allele dosage. It also easily provides the posterior probabilities of quantitative reproductive modes in autopolyploid populations genotyped at two‐time steps and a graphical representation of the minimum spanning trees of the genetic distances between polyploid individuals, facilitating the interpretation of the genetic coancestry between individuals in hierarchically structured populations. GenAPoPop complements the previously existing solutions, including SPAGEDI and POLYGENE, to use genotypings to study the ecology and evolution of autopolyploid populations. It was specially developed with a simple graphical interface and workflow, and comes with a simulator to facilitate practical courses and teaching of population genetics for autopolyploid populations
Investigating fish reproduction phenology and essential habitats by identifying the main spatio-temporal patterns of fish distribution
No full textInternational audienceFish spawning phenology is a major concern for conservation and fisheries management. New intensive data sources, such as GPS-based tracking data and high-resolution catch declaration data, are becoming increasingly available in the field of marine ecology. These data benefit from high spatiotemporal resolution and open new research avenues for investigating the interannual variability in fish phenology. In this paper, we demonstrate how an integrated species distribution model informed by commercial catch data combined with spatiotemporal dimension reduction methods known as empirical orthogonal functions (EOFs) can be used to synthesize spatiotemporal signals in fish reproduction phenology. Specifically, we address the following questions: (1) Can we identify seasonal spatial patterns that can be interpreted in terms of reproductive phenology and essential habitats? (2) Can we identify changes in reproductive phenology over time? (3) Are these changes related to environmental drivers? The analysis illustrates the reproductive phenology of three key commercial species in the Bay of Biscay (sole, hake, and sea bass). The EOF analysis emphasized strong seasonal spatiotemporal patterns that correspond to reproduction patterns and feeding patterns. Based on this methodology, we identified seasonal variations in the timing of reproduction, and we related these variations to sea surface temperature, a key driver of fish reproduction
When economy meets ecology, is it truly conflicted? A dashboard approach to assess the sustainability performance of European tropical tuna purse seine fisheries
No full textInternational audienceThe development of an ecosystem approach to fisheries management makes the assessment of the sustainability performance of fisheries a priority. This study examines European tropical tuna purse seine fleets as a case study, employing a multidisciplinary dashboard approach to evaluate historical and current sustainability performances. The aim is to enhance comprehension of the interconnected dimensions of sustainability and pinpoint management policy priorities. Using 18 indicators, we assessed the environmental, economic and social sustainability performances of European tropical tuna purse seine fleets, comparing them with other industrial tropical tuna fishing fleets in the Atlantic and Indian Oceans. The analysis also explored the temporal trend of sustainability performance for European tuna purse seiners from 2009 to 2019. Our results suggest that, compared with gillnetters and longliners, purse seiners and baitboats have a greater species -based selectivity, thereby catching fewer endangered, threatened or protected species, but a lower mature tuna catch rate, thus capturing more juveniles. We identify likely gaps in bycatch data reported by fishing on fish aggregating devices (FADs), due to results regarding selectivity and discard rates that appear inconsistent in the light of the scientific literature. The greater use of FADs, likely caused by the global tuna market, by purse seiner seems result in decreased ecological performances, as suggested by an increased carbon footprint per tonne landed. At the same time, it implies a better economic performance on the short-term, with higher net profit, energy efficiency (fuel consumed relative to monetary value created) and catch. For our case study, Ecology and Economy might seem to be in conflict for short-term perspective. However, consideration of the long-term impacts of FAD fishing and market incentives for fishing on free schools should lead purse seiner fleets to reduce drifting FAD fishing and promote more sustainable fishing practices
Regulating Congestion with Fee-Based versus Nonfee Management Measures: Application of a Repeated Random Utility Model to Outdoor Recreation
No full textInternational audienceOpen-access policies for coastal recreation areas in France can negatively impact landscape quality and lead to crowding. Our main objective is to simulate the effects of using public policies to regulate access to these sites. We estimate a repeated random utility model to explain the choice of participating and visiting coastal sites with a congestion variable. Since congestion is a result of a Nash equilibrium and is likely to be endogenous, an instrumental variable approach is used to both estimate congestion at the visitation equilibrium and control for its endogeneity. We use data from a survey of visitors to 43 coastal sites in western France (Brittany). When congestion is instrumented, it becomes a deterrent attribute in the choice of visiting a coastal area. We then simulate alternative access management policies and find that a mix of parking fees and increased walking distances at site entrances have the greatest effect on reducing congestion
Feeding strategy in organic pig farming as a lever to improve various quality dimensions of pork
No full textInternational audienceSince 2022, European specifications for organic pig farming have evolved to distribute 100 % organic feed, to reinforce the link to the soil with feed resources that should primarily be obtained from the farm or the same region. Feeding strategy acts as a lever to improve various quality dimensions of organic (as well as conventional) pork, including intrinsic dimensions (carcass composition, nutritional, organoleptic, technological, sanitary qualities) and extrinsic dimensions related to animal farming (image). Diet may also influence the risk of undesirable odours or flavours that may be found in pork from non-castrated male pigs. This study aimed at evaluating the effects of a specific feeding strategy on several quality dimensions of organic meat from non-castrated male pigs. The experiment was conducted with 77 organic non-castrated male pigs (Piétrain NN × Large White) reared according to organic specifications and distributed in two batches. Within litters, male littermates were allocated at around 33 kg of live weight to either a Control group which received a Control feed (C) corresponding to the organic specifications, or in a Bio+ group which received an organic test feed based mainly on French raw materials and which contained more fibres (faba bean and access to roughages) and omega-3 fatty acids (linseed, camelina). All pigs were reared in the same building on deep straw bedding (1.3 m²/pig) with free outdoor access (1.0 m²/pig) using one pen per experimental group. Pigs were fed ad libitum until slaughter at about 125 kg live weight. Average daily gain, carcass weight and lean meat content did not differ significantly between C and Bio+ pigs. Compared to C, Bio+ pigs had higher (P < 0.05) ultimate pH in the loin (Longissimus muscle) and ham (Gluteus medius, and Semimembranosus) muscles, associated to a lower Longissimus muscle glycolytic potential (P < 0.001). Loin and ham meat from Bio+ vs C pigs was less light (P < 0.05) and had a more intense red color (P < 0.10). The Bio+ strategy led to lower Longissimus muscle n-6:n-3 fatty acid ratio (P < 0.001), indicating an improvement in pork nutritional value. Backfat skatole concentration was lower in Bio+ than C pigs whereas backfat androstenone was higher in Bio+ than C pigs (P < 0.05). Altogether, we demonstrated that the Bio+ strategy had positive impacts on several qualities of organic pork from entire male pigs
Seed predation reduces weed biomass and contributes to crop productivity in arable fields
No full textInternational audienceWeed seed predation is a widespread process that can contribute to the biological control of weeds but we still lack empirical quantification of the effects of weed seed predators on weed dynamics. Besides, if weed dynamics are affected by seed predation, one can expect that seed predators will indirectly positively affect crop productivity, but such assessment has to our knowledge never been conducted. Here, we report on a highly replicated predator exclosure experiment that aimed to assess the impact of seed predators on the demography of nine weed species and on crop productivity. We demonstrate that across the 28 experimental fields, seed predation significantly reduced total weed biomass, compared to the reference where predators were excluded. Moreover, we show that in the absence of seed predators, the potential wheat crop yield is reduced by 80 % by weeds. The presence of seed predators strongly limits this drastic reduction, to 48 % with invertebrate seed predators to 56 % with both invertebrate and vertebrate seed predators
Plant and animal protein mixed systems as wall material for microencapsulation of Mānuka essential Oil: Characterization and in vitro release kinetics
No full textInternational audienceCombination of plant and animal protein diet is becoming a valuable source of nutrition in the modern diet due to the synergistic functional properties inherent in these protein complexes. Moreover, the synergy between animal and plant proteins can contribute to the high stability and improved solubility of the encapsulated bioactive ingredients (e.g., essential oils). Therefore, the study was designed to evaluate the plant (pea protein (PP) and lupine protein (LP)) and animal protein (whey protein, WP) mixed systems as a wall material for microencapsulation of mānuka essential oil, as an example of bioactive compound. Moreover, physicochemical properties and in vitro release profile of encapsulated mānuka essential oil were studied. Mānuka essential oil microcapsules exhibited low moisture content (5.3–7.1 %) and low water activity (0.33–0.37) with a solubility of 53.7–68.1 %. Change in wall material ratio significantly affected the color of microcapsules, while microcapsules prepared with 1:1 protein/oil ratio demonstrated a high encapsulation efficiency (90.4 % and 89.4 %) for protein mixed systems (PP + WP and LP + WP), respectively. Microcapsules further showed low values for lipid oxidation with a high oxidative stability and antioxidant activity (62.1–87.0 %). The zero order and Korsmeyer–Peppas models clearly explained the release mechanism of encapsulated oil, which was dependent on the type and concentration of the protein mixed used. The findings demonstrated that the protein mixed systems successfully encapsulated the mānuka essential oil with controlled release and high oxidative stability, indicating the suitability of the protein mixed systems as a carrier in encapsulation and application potential in development of encapsulated functional foods
Macronutrient digestion and nutritional quality: how to measure it and what matters?
No full textInternational audienceFood digestion and nutrient absorption efficiency and kinetics are important parameters for futher metabolic use. They can be influenced by different food properties, such as the structure and the fine composition, but also by the host digestion capacity. The present talk will illustrate these concepts through results from our research group obtained either through in vivo models (pig or human) or in vitro models (static and dynamic conditions). For instance, we have demonstrated that, at identical composition, differences in dairy product macrostructure lead to differences in gastric emptying and protein digestion. For similar macrostructure, differences at the microscopic scale can also impact food digestion kinetics, as shown for egg white gels and protein hydrolysis kinetics but also for infant milk and lipid and protein hydrolysis kinetics. Other examples of how lipid structuration can impact on the bioaccessibility/bioavailability of essential fatty acids such as DHA will be given. Besides food structure, the composition of the food or the meal can influence the digestion mechanisms, particularly for plant-based foods containing fibers, anti-nutritional factors, polyphenols, …. Finally, the host is also an important modulating factor, especially when considering the physiological stage, from infant to senior, such as demonstrated through in vitro approaches. Overall, beyond food composition, the structure of food at different length scales can be considered as an important lever to control the kinetics of nutrients release during digestion and fulfil the nutritional needs of specific populations (elderly, infant, …)