Positive associations among rare species and their persistence in ecological assemblages
According to the competitive exclusion principle, species with low competitive abilities should be excluded by more efficient competitors; yet, they generally remain as rare species. Here, we describe the positive and negative spatial association networks of 326 disparate assemblages, showing a general organization pattern that simultaneously supports the primacy of competition and the persistence of rare species. Abundant species monopolize negative associations in about 90% of the assemblages. On the other hand, rare species are mostly involved in positive associations, forming small network modules. Simulations suggest that positive interactions among rare species and microhabitat preferences are the most probable mechanisms underpinning this pattern and rare species persistence. The consistent results across taxa and geography suggest a general explanation for the maintenance of biodiversity in competitive environments.
(Nature Ecology & Evolution. vol. 4, n° 2397-334X, pp. 40-45, 22/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Measuring Air Pollutant Concentrations and Fluxes
Estimating agriculture’s contribution to air pollution and global warming is needed to understand and limit its impacts on the environment and climate. It is equally important to estimate the capacity of agricultural practices to mitigate these emissions and to characterize atmospheric deposition and the impacts of air pollutants on agroecosystems. This chapter presents methods for measuring air pollutant concentrations, their fluxes at the soil-vegetation-atmosphere interface, and emissions from livestock facilities. Methods for measuring air concentrations are described with a focus on compounds emitted from or impacting agriculture (including forests): ammonia, nitrogen oxides, pesticides, volatile organic compounds including methane, abiotic and biotic particles, and ozone. The main methods for measuring emission and deposition fluxes of air pollutants between terrestrial surfaces, especially agroecosystems, and the atmosphere are described with a specific focus on the eddy covariance method as well as on emissions from livestock buildings. Then the general principles of source apportionment methods for estimating emissions spatial variability are presented. To address the questions on atmospheric chemistry, the methods used for measuring the reactivity of atmospheric compounds are presented. Finally, an insight is given on the developments of measurement methodologies to address new compounds and improve the sensors’ sensitivity and response time as well as provide estimates of spatial variability of concentrations and fluxes at larger scales.
(pp. 119-157, 22/04/2026)
ECOSYS, INRAE, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, LISA (UMR_7583), INSU - CNRS, UPEC UP12, CNRS, UPCité, LATMOS, UVSQ, INSU - CNRS, SU, CNRS, PhLAM, CNRS, IRCELYON, UCBL, INC-CNRS, CNRS, SAS, INRAE, Institut Agro, IGE, IRD, INSU - CNRS, CNRS, Fédération OSUG, UGA, Grenoble INP, UGA, ICARE, UO, CNRS, INSIS - CNRS, ICPEES, UNISTRA, INC-CNRS, CNRS, MNGE, UNISTRA, Université de Haute-Alsace (UHA), INSERM, INC-CNRS, CNRS, PC2A, CNRS, LCE, AMU, INC-CNRS, CNRS, IMT Lille Douai, IMT, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
A 14-Year Multi-sites and High-Frequency Monitoring of Salinity in the Tidal Garonne River (S-W France) Reveals Marked Inter-annual Variability in Marine Intrusion
With its 625 km2, the Gironde estuary (S-W France) is one of the largest European estuaries. The tidal Garonne and Dordogne Rivers, whose confluence is located at about 75 km from the mouth, form its fluvial section. The Tidal Garonne River (TGR) represents about 2/3 of the freshwater inputs to the Gironde. For a long time it has been accepted the limit of saline intrusion, identified by a salinity higher than 0.5, was nearly at the confluence. In the last decades, there has been a significant decrease of the annual mean TGR discharge, likely to influence marine intrusion. It is often difficult to establish changes in marine intrusion in estuaries due to the limited available data set. This work presents the interest of a multi-sites and high frequency monitoring system, called MAGEST, that records since 2004 four physico-chemical parameters, including salinity, to establish a reference database of water-quality of this large fluvio-estuarine system, in order to address current and future water-quality issues, including saline intrusion. This work presents in details the 14-year time series of salinity along the Garonne-Gironde continuum. Not surprisingly, there are large differences among the instrumented stations depending on their localization. High-frequency salinity chronic at Bordeaux is used to assess the occurrence of saline intrusion in the Tidal Garonne River, revealing marked inter-annual variability in marine intrusion depending of fluvial discharge. The ongoing regional changes suggest an increase of salinity in TGR in the next decades.
(pp. 3-11, 22/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Sensitivity to cadmium of the endangered freshwater pearl mussel Margaritifera margaritifera from the Dronne River (France): experimental exposure
Margaritifera margaritifera is a critically endangered species in Europe. Among the causes explaining its decline, metal pollution had never been deeply studied. Thus, an ecotoxicological investigation was developed on this species which comes from the Dronne River (South-West of France). Cadmium (Cd) exposure of mussels at 2 and 5 μg/L for 7 days was conducted to test their vulnerability to this metal, and also the potential endocrine disruption power of Cd. Morphometric analyses, gonad histological observations, metal bioaccumulation, metallothionein (MTs) production, measures of malondialdehyde (MDA), and finally quantitative relative expression analysis of genes involved in various metabolic functions were performed. The main results showed Cd accumulation increasing in a dose-dependent manner, especially in the gills. The same trend was observed for gene expression relative to oxidative stress. Histological analysis of the gonads highlighted a predominance of hermaphrodite individuals, but after 7 days of exposure to Cd, the percentage of female was largely increased compared with controls, from 17 to 33%. These results demonstrate the endocrine disruption effect of Cd on freshwater pearl mussels.
(Environmental Science and Pollution Research. vol. 27, n° 0944-1344, pp. 3715-3725, 22/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
AquaVIT Quand les plantes aquatiques invasives transcendent les frontières : approche pluridisciplinaire des relations entre espèces, milieux et gestionnaires
Le projet de recherche AquaVIT vise à accompagner l’évolution des modalités de gestion des grands lacs aquitains, confrontés à des enjeux environnementaux liés à la colonisation par les plantes aquatiques invasives. Ces plantes exotiques à caractère envahissant peuvent occuper une place importante au sein des écosystèmes lacustres et, par la même occasion, entraver de nombreux usages des lacs, notamment la pratique d’activités de loisirs. En Nouvelle-Aquitaine, ces macrophytes invasifs font l’objet d’une attention de la part des gestionnaires, élus et scientifiques depuis maintenant plus de trente ans. Néanmoins, un certain nombre d’interrogations demeurent. Les plantes présentent encore des dynamiques de colonisation importantes dans de nombreux plans d’eau et les opérations de gestion visant à les réguler sont menées localement. Le projet de recherche AquaVIT s’intéresse particulièrement aux questions suivantes : - Les plantes invasives constituent-elles un élément perturbateur du bon fonctionnement écologique lacustre ? - Comment "faire avec" les plantes au quotidien ? - Comment "faire ensemble" ? Le projet AquaVIT affiche une ambition pluridisciplinaire forte, qui associe, dès sa conception, les sciences humaines et sociales d’une part, et les sciences biogéochimiques et écologiques d’autre part. Ce projet propose une alternative à la vision quantitative et mesurable, strictement centrée sur la plante (i.e distribution et biomasse des plantes), vers une approche plus qualitative, orientée sur les relations entre la plante et son environnement, celui-ci étant considéré d’un point de vue écosystémique et social. Appropriée par chacune des disciplines, cette posture a donné lieu à des approches empiriques diverses et spécifiques. Dans le projet AquaVIT ont été déployées, entre autres, des enquêtes (qualitatives et quantitatives) auprès des acteurs, des études sociohistoriques basées sur des analyses de documents, mais aussi des prélèvements et mesures biologiques et physico-chimiques in situ, ainsi que des expérimentations en laboratoire. Le croisement de ces regards et de ces méthodes constitue une des richesses du projet. Les résultats obtenus invitent à s’éloigner d’une représentation univoque des conséquences potentielles de la présence d’herbiers denses de plantes aquatiques invasives, tout comme à contextualiser la problématique socio-environnementale de leur gestion. Ceci peut être illustré par le fait que les processus écologiques et biogéochimiques à l’œuvre dans les herbiers sont étroitement liés aux conditions hydrodynamiques locales, ou encore que les représentations et les attitudes à leur sujet dépendent pour partie des usages et des pratiques de terrain. Dans certaines conditions, une telle « contextualisation » de la problématique a favorisé l’émergence d’innovations organisationnelles, se traduisant, par exemple, par des dispositifs à caractère participatif. En dépit des motivations et des intentions à s’engager, dont témoignent les usagers des plans d’eau, les soutiens (humains, techniques et financiers) des pouvoirs publics, restent essentiels. Sur un plan spatial, ces innovations peinent toutefois à dépasser l’échelle des sites, de sorte que la mise en relation entre plusieurs secteurs, que l’on est parfois en mesure d’attendre compte tenu de la dynamique des plantes et des processus, repose encore très largement sur les réseaux sociotechniques des gestionnaires traditionnels des milieux, et peu sur les utilisateurs finaux.
(pp. 125 p., 22/04/2026)
UR EABX, INRAE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR ETBX, INRAE
Ecosystem services provided by a non-cultured shellfish species: The common cockle Cerastoderma edule
Coastal habitats provide many important ecosystem services. The substantial role of shellfish in delivering ecosystem services is increasingly recognised, usually with a focus on cultured species, but wild-harvested bivalve species have largely been ignored. This study aimed to collate evidence and data to demonstrate the substantial role played by Europe's main wild-harvested bivalve species, the common cockle Cerastoderma edule, and to assess the ecosystem services that cockles provide. Data and information are synthesised from five countries along the Atlantic European coast with a long history of cockle fisheries. The cockle helps to modify habitat and support biodiversity, and plays a key role in the supporting services on which many of the other services depend. As well as providing food for people, cockles remove nitrogen, phosphorus and carbon from the marine environment, and have a strong cultural influence in these countries along the Atlantic coast. Preliminary economic valuation of some of these services in a European context is provided, and key knowledge gaps identified. It is concluded that the cockle has the potential to become (i) an important focus of conservation and improved sustainable management practices in coastal areas and communities, and (ii) a suitable model species to study the integration of cultural ecosystem services within the broader application of 'ecosystem services'.
(Marine Environmental Research. vol. 158, n° 0141-1136, pp. 104931, 22/04/2026)
LEFE, INEE-CNRS, CNRS, UT3, Comue de Toulouse, CNRS, Toulouse INP, Comue de Toulouse, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, NERC, MARE, UKCEH, NERC, UKCEH, BEES, UCC, BOREA, UNICAEN, NU, MNHN, IRD, SU, CNRS, UA
Poly-phased fluid flow in the giant fossil pockmark of Beauvoisin, SE basin of France
The giant Jurassic-aged pockmark field of Beauvoisin developed in a 800 m wide depression for over 3.4 Ma during the Oxfordian; it formed below about 600 m water depth. It is composed of sub-sites organized in clusters and forming vertically stacked carbonate lenses encased in marls . This fine-scale study is focused on a detailed analysis of petrographical organization and geochemical signatures of crystals that grew up in early to late fractures of carbonate lenses, surrounding nodules, and tubes that fed them. The isotopic signature (C, O and Sr) shows that at least three different episodes of fluid migration participated to the mineralization processes. Most of the carbonates precipitated when biogenic seepage was active in the shallow subsurface during the Oxfordian. The second phase occurred relatively soon after burial during early Cretaceous and thermogenic fluids came probably from underlying Pliensbachian, Late Toarcian or Bajocian levels. The third phase is a bitumen-rich fluid probably related to these levels reaching the oil window during Mio-Pliocene. The fluids migrated through faults induced by the emplacement of Triassic-salt diapir of Propiac during the Late Jurassic and that remained polyphased drain structures over time.
(Bulletin de la Société Géologique de France. vol. 191, n° 0037-9409, pp. 35, 22/04/2026)
INSU - CNRS, UM, CNRS, UA, GEOAZUR 7329, INSU - CNRS, UniCA, CNRS, IRD [Occitanie], UniCA, LOG, INSU - CNRS, ULCO, CNRS, IRD [Ile-de-France], EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LDO, INSU - CNRS, UBO EPE, CNRS, UB
Bioaccumulation dynamics and gene regulation in a freshwater bivalve after aqueous and dietary exposures to gold nanoparticles and ionic gold
Gold nanoparticles (AuNPs) are being developed and produced for a wide variety of industrial and biomedical applications, which raises the concern about their release and potential effects in the environment. In this study, we aim to assess the effects of PEGylated AuNPs and ionic gold on the freshwater bivalve Corbicula fluminea. As NP bioavailability is conditioned by many factors of variability, we focused on the determination of biodynamic parameters which control AuNP uptake and elimination in bivalves. Three experiments were conducted: (1) a waterborne exposure (0–24 mg/L for AuNPs and 0–12 mg/L for ionic gold), (2) a dietborne exposure (0–48 mg/L for AuNPs and 0–24 mg/L for ionic gold), and (3) an elimination phase (after waterborne exposure to 12 mg/L for AuNPs and 24 mg/L for ionic gold), to calculate rate constants for uptake from water(kuw), from food (kuf), and for the physiological elimination (ke) for AuNPs and AuCl(OH)3−. Jointly, the relative expression of several genes was investigated in the hemolymph cells to relate AuNPs and gold ion exposures to detoxification, oxidative stress, immune, and apoptosis responses in C. fluminea. Results show that kuw and kuf were around 10 and 30 times higher for AuNPs compared to AuCl(OH)3−, respectively. The ke was also faster in clams exposed to AuNPs meaning that they also had greater excretion capacities in comparison to gold ions. Water seems to be the main exposure pathway for C. fluminea according to kuw and kuf values for AuNPs and AuCl(OH)3− (kuw = 0.28 and 0.03, kuf = 0.009 and 0.001, respectively). The gene analyses pointed out important responses against oxidative stress, strong activations of genes of the immunity, and apoptosis after the waterborne exposure to AuNPs and to a lesser extent after exposure to gold ions. Very few responses were observed after the dietary exposure to both forms of gold, probably due to valve closure in response to contamination. While some studies suggest that the toxicity of nanoparticles may come from the release of metal ions, our results showed that the AuNPs we used were very stable (less than 1% of ion release) and generated more effects at the gene level than ionic gold. Therefore these results highlight the strong potential of toxicity of AuNPs compared to ionic gold and raise new concerns about the toxicity inherent to NPs in the environment.
(Environmental Science and Pollution Research. vol. 27, n° 0944-1344, pp. 3637-3650, 22/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ICMCB, UB, INC-CNRS, CNRS
Simulating the Impact of Sea-level Rise and Offshore Bathymetry on Embayment Shoreline Changes
LX-Shore is a reduced-complexity shoreline change model driven by cross-shore and longshore processes which can account for man-made or natural non-erodible areas such as groynes and headlands. Here we describe and further test the implementation of two recent developments allowing to account for (i) real and non-erodible offshore bathymetric features such as rocky outcrops and canyons affecting offshore wave transformation and, in turn, shoreline variability and (ii) shoreline retreat due sea-level rise. After a description of the numerical developments, the benefits of these new developments are demonstrated with the application of LX-Shore to an idealized embayed beach exposed to real wave climate during a 10-yr period. Three simulations are conducted to test the impact of an outcrop in the middle of the embayment and of a gradual 1-m sea-level rise on shoreline spatial and temporal modes of variability. Results show that the equilibrium planview shoreline and the shoreline variability are strongly impacted by only slightly modifying the bathymetry and varying the mean sea level. These results show the potential of LX-Shore to better understand and further predict shoreline change along real coasts exhibiting mixed (sandy/rocky) and complex seabed morphologies and undergoing sea-level rise.
(Journal of Coastal Research, n° 0749-0208, pp. 1263-1267, 22/04/2026)
BRGM, CNRS, UB, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
The Iso2k database: a global compilation of paleo-δ18O and δ2H records to aid understanding of Common Era climate
Reconstructions of global hydroclimate during the Common Era (CE; the past ∼2000 years) are important for providing context for current and future global environmental change. Stable isotope ratios in water are quantitative indicators of hydroclimate on regional to global scales, and these signals are encoded in a wide range of natural geologic archives. Here we present the Iso2k database, a global compilation of previously published datasets from a variety of natural archives that record the stable oxygen (δ18O) or hydrogen (δ2H) isotopic compositions of environmental waters, which reflect hydroclimate changes over the CE. The Iso2k database contains 759 isotope records from the terrestrial and marine realms, including glacier and ground ice (210); speleothems (68); corals, sclerosponges, and mollusks (143); wood (81); lake sediments and other terrestrial sediments (e.g., loess) (158); and marine sediments (99). Individual datasets have temporal resolutions ranging from sub-annual to centennial and include chronological data where available. A fundamental feature of the database is its comprehensive metadata, which will assist both experts and nonexperts in the interpretation of each record and in data synthesis. Key metadata fields have standardized vocabularies to facilitate comparisons across diverse archives and with climate-model-simulated fields. This is the first global-scale collection of water isotope proxy records from multiple types of geological and biological archives. It is suitable for evaluating hydroclimate processes through time and space using large-scale synthesis, model–data intercomparison and (paleo)data assimilation. The Iso2k database is available for download at https://doi.org/10.25921/57j8-vs18 (Konecky and McKay, 2020) and is also accessible via the NOAA/WDS Paleo Data landing page: https://www.ncdc.noaa.gov/paleo/study/29593 (last access: 30 July 2020).
(Earth System Science Data. vol. 12, n° 1866-3508, pp. 2261-2288, 22/04/2026)
WUSTL, SibFU, SAGES, UOR, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LSU, ANSTO, UON, MARUM, CEREGE, IRD, AMU, CdF (institution), INSU - CNRS, CNRS, INRAE, IISER Pune, CSIC, AWI, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, SUNY Buffalo, SUNY, ANU, FSU, OCCR, UNIBE, UNIBE, UIUC, AAD, JGU, MTA, UC Santa Barbara, UC, LOCEAN-VALCO, LOCEAN, MNHN, IRD, INSU - CNRS, SU, CNRS, IPSL (FR_636), ENS-PSL, UVSQ, CEA, INSU - CNRS, X, CNES, SU, CNRS, UPCité, UNIPA, ICTA, UAB, LOCEAN-VOG, LOCEAN, MNHN, IRD, INSU - CNRS, SU, CNRS, IPSL (FR_636), ENS-PSL, UVSQ, CEA, INSU - CNRS, X, CNES, SU, CNRS, UPCité, IIS, UTokyo