Deep dive into the Surface MicroLayer (SML) of Brest harbour

International audienceThe surface microlayer (SML) is an exchange interface between the atmosphere and the hydrosphere, about 1mm thick, with chemical, physical and biological processes that differ from the Sub Surface Water (SSW) layer. It is also defined as a short-term bioaccumulator. Well-studied in the open ocean and costal areas, this microenvironment is less regarded in closed basins such as harbours. Brest harbour is home to a wide range of activities and therefore has multiple impacts. The aim of this study is to investigate the SML in a multipurpose harbour (Brest) in terms of microbiological biodiversity, physicochemical and polycyclic aromatic hydrocarbons (PAH’s) composition

Unveiling the potential and specificity of the Mahoran ethnopharmacopoeia: A field survey

International audienceEthnopharmacological relevance: A significant portion of Mahoran people relies on traditional medicine to addresstheir healthcare needs. However, very few studies have been carried out on this subject, and few data areavailable on the practices, plants used, and ailments most commonly treated by their traditional medicine.Aim of the study: Within this context, the aim of this study was to identify the diseases most commonly treated bytraditional Mahoran medicine, as well as the plants most commonly used against these various ailments.Materials and methods: From January to April 2023, a semi-structured survey was carried out in Mayotte island. Atotal of 103 participants were interviewed including 65 non specialists, 21 knowledgeable, and 17 specialists. Athorough literature review was performed on the most cited plant species to evaluate the benefit-risk of eachremedy.Results: Participants mentioned using 474 remedies (prepared mostly with herbal ingredients) to treat 65 dis-eases. These diseases belong to various health categories of which the most represented ones were digestivesystem, respiratory system, genital system, general, and muscular system. The two most common ailments citedby participants were stomachache (41/103) and cough (36/103). A total of 154 plant species were identified,with Coleus amboinicus, Citrus aurantiifolia, Moringa oleifera, and Ocimum gratissimum being the main plants re-ported. Massage therapy was the second most important traditional practices reported after the use of herbalremedies.Conclusion: Our survey confirms the importance of traditional medical pratices in Mayotte island. The followingplants: Aerva lanata, Cardiospermum halicacabum, Coleus madagascariensis Paullinia pinnata, and Woodfordia fru-ticosa stand out from the others in terms of their use and number of citations, and it would be interesting to studytheir pharmacological and toxicological properties. Traditional medicine in Mayotte also possesses specificities,notably with the use of particular ingredients such as salt, coral stone, or even white clay. Furthermore,throughout the study, we noticed that chronic diseases such as diabetes or hypertension were extensively treated.This could be linked to the fact that the prevalence of these diseases is quite high on the island

Evaluation of three modelling frameworks of thermal infrared radiative transfer for directional anisotropies of temperatures

International audienceRadiative transfer models (RTMs) designed to reproduce the anisotropy of surface brightness temperature are particularly useful for applications on Earth’s energy budget when using remote sensing data sets. Despite the fact that several thermal infrared (TIR) RTMs have been developed, a quantitative analysis comparing the benefits and limits of these models remains necessary. Herein, three modeling frameworks (physical hybrid, analytical parameterization, kernel-driven) have been evaluated comparatively for a homogeneous vegetation, a row-planted crop and a sparse forest. Airborne measurements and the Discrete Anisotropy Radiative Transfer (DART) model simulations were retained as the benchmark. Forward modeling and inverse fitting schemes were proposed for the sake of comparison. Results reveal that: 1) in the forward modeling scheme, from airborne measurements, the hybrid model performs better with RMSEs of 0.17℃, 1.57℃, and 0.38℃ for homogenous, row-planted vineyard and sparse forest scenes, respectively; the analytical model appears similar performant (0.17℃, 0.40 ℃) for the homogeneous and sparse forest scenes, but less performant (2.39℃) for the row-planted scene; 2) In the inverse fitting scheme, the uncertainties (95% of probability) of model coefficients and predicted directional anisotropies were considered. The kernel-driven model has fewer modeling constraints and statistically performs better for the homogeneous and sparse forest scenes with RMSEs of 0.07 ℃ and 0.19 ℃, respectively whereas it is less efficient for the row-planted scene with RMSE of 0.80 ℃. This study highlights the differences of accuracy between models of different complexity, and provides reference information for researchers to improve existing models and for users to choose their best modeling solution

Editorial

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Is provisioning rate of parents and helpers influenced by the simulated presence of novel individuals?

International audienceCooperative behaviour is widespread in animals and is likely to be the result of multiple selective pressures. A contentious hypothesis is that helping enhances the probability of obtaining a sexual partner (i.e., confers direct benefits through sexual selection). Under this hypothesis, cooperative behaviours may have evolved into a signal. Consequently, we would expect individuals to enhance cooperation when a potential mate is present, to signal their status and quality. We evaluated this possibility in the cooperatively breeding sociable weaver (Philetairus socius). We simulated the presence of different types of individuals using a playback to test whether the simulated presence of an unknown individual, possibly a potential mate, increases provisioning rate in two classes of cooperating birds : breeders and helpers. If the signal is the provisioning rate in itself we expected increased feeding rates of male helpers during the simulated presence of an unknown female. Contrary to our predictions, the simulated presence in the audience of an unknown individual did not influence the nestling provisioning rate of birds of any sex and class. From these results, we conclude that in this species the variation in provisioning rate is unlikely to be used as a signal in a sexual selection context. However, we also highlight the limitations of our methods and suggest improvements that future studies should incorporate when testing audience effects on cooperation. Significance statementAnimals may cooperate to gain direct benefits, like attracting mates. This happens for example in humans. In species where cooperation leads to direct sexual benefits, when the appropriate audience is present, (i.e., a potential mate), helpers should enhance their cooperation. To determine whether helping to raise others' young varies according to who is watching, we used playbacks to simulate the presence of unknown individuals of opposite sex (potential mates) while helpers were feeding young. Helping, quantified here as number of times food was brought to the chicks over an hour, was not affected by the simulated audience. We concluded that in sociable weavers variation in provisioning rate is unlikely to be a signal to obtain direct sexual benefits.</div

Editorial: Changes in plant–herbivore interactions across time scales: bridging paleoecology and contemporary ecology

International audienceEditorial on the Research TopicChanges in plant-herbivore interactions across time scales: bridging paleoecology and contemporary ecology Plants and arthropods predominate in terrestrial ecosystems, both in biodiversity and biomass (Bar-On et al., 2018). Their trophic interactions, primarily herbivory, have profoundly shaped terrestrial ecosystems, affecting evolutionary trajectories, ecosystem structures, and responses to environmental change. The fossil record provides key insights into long-term processes and large-scale patterns of arthropod (mainly insect) herbivory stretching back to early terrestrial ecosystems, such as the Silurian (~443-419 million years ago) and Devonian (~419-359 million years ago) (Labandeira and Wappler, 2023), despite limitations from temporal and spatial gaps and the need to deduce ecological patterns based on insect morphology, community composition, and plant damage caused by herbivores. Contemporary ecology, in contrast, allows for direct real-time observation and precise measurement of variables related to herbivory, though it lacks the expansive temporal scope.Ideally, our understanding of plant-insect interactions would integrate insights from both ancient and modern ecosystems, spanning ecological (particularly macroecological) and evolutionary patterns across geologic timescales and present-day contexts, with implications for the future. The five manuscripts in this Research Topic contain a multitude of paleoecological insights that will interest specialists in both ancient and modern ecosystems.</div

Multi-model assessment of the role of anthropogenic aerosols in summertime climate change in Europe

International audience1) The role of anthropogenic aerosols in European summertime climate change is assessed using a set of multi-model regional climate simulations• (2) Reduced concentrations of anthropogenic aerosols in Europe lead to an increase in surface solar radiation and an extra warming near surface • (3) Current differences in aerosol representation explain a part of inconsistencies between global and regional climate projections in Europe</div

Deciphering the environmental background of a roman brick and tile works in Mariana (Pruniccia, Lucciana, Corsica) with geomorphology, palaeoentomology and archaeobotany

International audienceCombined evidence from insect and plant remains was recovered from separate areas of a Roman brick works at the site of Pruniccia (Corsica), in an area adjacent to the Roman town of Mariana. Their interpretation helps us to reconstruct the specific activities undertaken and broaden our understanding of how human activities affected the composition of sub-fossil plant and insect assemblages. After including geomorphological evidence, we also assess the local environmental conditions of the site. In well PT20019, an unexpected abundance and diversity of insects characteristic of aquatic habitats contrasts with results from fruits and seeds, prompting questions on the taphonomic processes involved. The relatively small number of woody taxa identified from charcoal in kiln FR200002 and the related working area (FS20088) includes trees and shrubs that would have been easily accessible nearby. The detection of insect damage in Alnus wood is consistent with the repeated finds of insects which attack wood. This suggests that firewood may have been collected in advance and stored until needed. More generally, our work illustrates the variety of habitats in the area around the Roman town and helps us compensate for the shortage of palaeoenvironmental information available locally up to now

Navigating human–plant reciprocity: commercial harvesting by professionals of a medicinal plant fosters multi‐actor landscape management

International audienceStudies of human–nature relationships increasingly recognise not only nature's contributions to people but also the positive contributions of human practices to ecosystems. The concept of reciprocal contributions emphasises positive human–nature relationships. But trade‐offs between natural elements implies that human favouring of one element (e.g. via the protection of its habitat) can be detrimental to others. Discussing the concept of reciprocal contributions encourages us to rethink human management of landscape by shifting from a primary focus on instrumental values associated with plant extraction, to relational values related to the multiple interests of human and non‐human actors. To study how relational values are integrated into the configuration of multifunctional landscapes, we focused on professional harvesters of Arnica montana . We asked what role professional harvesters play in the stewardship of their harvesting sites through reciprocal relations with plants, landscapes and other actors to shape the future of plant and landscape sustainability. We show that even though professional harvesters live far from their harvesting sites, they develop both a strong attachment to them, and an experience‐based ecological knowledge of the relationships between arnica and other plant species and the environment. This attachment and experience‐based knowledge provide harvesters with legitimacy in the eyes of other actors (e.g. cattle farmers, managers of natural areas, pharmaceutical and cosmetic laboratories) and allow them to play the role of mediator between these other actors and the harvested plant in order to influence the management of the environment—for example by burning, mowing or grazing. This creates a reciprocal benefit with this particular species, but also with other co‐occurring species. Integrating the interests of the harvesters with those of other stakeholders requires negotiation and the search for synergies between values. Synthesis and applications . Within the framework of ‘reciprocal contributions’, we argue that human engagement in reciprocal relations with specific species is read as a form of care that privileges the maintenance of certain lives over others; trade‐offs between plants but also between plants, animals, landscape and humans have to be incorporated in the theoretical framework. Read the free Plain Language Summary for this article on the Journal blog.Les études sur les relations entre les humains et la nature reconnaissent non seulement les contributions de la nature aux personnes, mais aussi les contributions positives des pratiques humaines aux écosystèmes. Le concept de contributions réciproques met en avant les relations positives entre les humains et la nature. Cependant, les compromis entre les éléments naturels impliquent que le fait de favoriser un élément par les humains (par exemple, en protégeant son habitat) peut être préjudiciable à d'autres. La discussion autour du concept de contributions réciproques nous encourage à repenser la gestion humaine des paysages en passant d'un focus principal sur les valeurs instrumentales associées à l'extraction des plantes, à des valeurs relationnelles liées aux intérêts multiples des acteurs humains et non humains. Pour étudier comment les valeurs relationnelles sont intégrées dans la configuration des paysages multifonctionnels, nous avons travaillé avec les cueilleurs professionnels d' Arnica montana . Nous avons cherché à comprendre le rôle que joue les cueilleurs dans la gestion durable de leurs sites de récolte à travers des relations réciproques avec les plantes, les paysages et d’autres acteurs humains pour façonner l'avenir de la durabilité des plantes et des paysages. Nous montrons que, bien que les cueilleurs professionnels vivent loin de leurs sites de récolte, ils développent à la fois un fort attachement à ces sites et une connaissance écologique basée sur l'expérience des relations entre l'arnica, les autres espèces végétales et l'environnement. Cet attachement et cette connaissance empirique fournissent aux cueilleurs une légitimité aux yeux des autres acteurs (par exemple, les éleveurs, les gestionnaires d'espaces naturels, les laboratoires pharmaceutiques et cosmétiques) et leur permettent ainsi de jouer le rôle de médiateur entre ces acteurs et la plante récoltée afin d'influencer la gestion de l'environnement—par exemple, par le brûlage, le fauchage ou le pâturage. Cela crée un bénéfice réciproque avec l’arnica, mais aussi avec d’autres espèces coexistant. L'intégration des intérêts des cueilleurs avec ceux des autres parties prenantes nécessite une négociation et la recherche de synergies entre les valeurs. Dans le cadre théorique des « contributions réciproques », les relations entre des humains et des espèces choisies, relèvent d’une forme de soin qui privilégie le maintien de certaines vies au détriment d’autres ; les interactions entre les plantes, mais aussi entre plantes, animaux, paysages et personnes impliquent des compromis qui doivent être intégrés au cadre théorique des « contributions réciproques »

Evidence of high carbon biodegradability in the subsoil of Mediterranean croplands

International audienceAlthough soil carbon is a key element for soil health and climate change mitigation, our understanding of its dynamics is still incomplete. Deep soil horizons are thought to contain mostly organic carbon stabilised at centennial or even millennia time scales. The present study aimed to investigate the common paradigm of high stability of soil carbon in deep soil horizons in semiarid Mediterranean cultivated environments. It was based on a combined assessment and analysis of soil organic carbon (SOC) contents, stocks, biodegradability, and radiocarbon age of eleven soil profiles in north-eastern Tunisia, in the context of soils developed on marine sedimentary parent material with very low to moderate soil inorganic carbon (SIC) content. SOC content and stocks were found to be typical of cultivated Mediterranean soils, with low SOC content (&lt;2%), decreasing with depth and a predominant stock of SOC in subsoils (&gt;30 cm). Our results first revealed high levels of carbon biodegradability for all the soils investigated, confirming that soil carbon in the Mediterranean context can be rapidly decomposed under optimal temperature and moisture conditions. They also showed that the biodegradability of carbon increased with depth, even in profiles with very low SIC contents, indicating that the organic fraction of subsoil carbon is likely to be less stable than that of topsoil carbon. The significant increase in SOC biodegradability with depth was supported by applying a literature-based correction for the contribution of SIC-derived CO 2 to soil respiration emissions. In addition, SOC biodegradability was strongly positively correlated with its radiocarbon age, implying that SOC stability decreases with increasing mean residence time. We explained these original results by a significant presence of very old and highly biodegradable organic carbon in the subsoil organic carbon pool, probably inherited from a Quaternary paleoenvironment and preserved since then due to the favourable preservation conditions associated with the semi-arid climate. Finally, this study highlights the great vulnerability of the millennia-old organic carbon pool stored in some deep horizons of Mediterranean soils, and the necessity to protect it from reconnection with the atmosphere. More broadly, it demonstrates the need to take greater account of the active role of old organic carbon in carbon cycle studies in these specific environments