Extreme Wave Events on Barrier Reefs: A Driver for Critical Regime?
This paper describes the hydrodynamic regimes reached over barrier reefs during extreme wave events. The study is based on a combined approach relying, on one hand, on an extensive in-situ experiment over the Ouano reef-lagoon system, New Caledonia and, on the other hand, on wave-resolving numerical modeling.
(Journal of Coastal Research. vol. 95, n° 0749-0208, pp. 654-658, 22/04/2026)
SIAME, UPPA, MIO, IRD, AMU, INSU - CNRS, UTLN, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, INSU - CNRS, UM, CNRS, UA, LOPS, IRD, IFREMER, INSU - CNRS, UBO EPE, CNRS
On the small‐scale fractal geometrical structure of a living coral reef barrier
Topographical complexity of coral reefs is of primary importance for a number of hydrodynamical and ecological processes. The present study is based on a series of high‐resolution seabottom elevation measurements along the Maupiti barrier reef, French Polynesia. Several statistical metrics and spectral analysis are used to characterize the spatial evolution of the coral geometrical structure from the reef crest to the backreef. A consistent fractal‐like power law exists in the spectral density of bottom elevation for length‐scales between 0.1 and 7m while, at larger scale, the reef structure shows a different pattern. Such a fine characterization of the reef geometrical structure provides key elements to reconstruct the reef history, to improve the representation of reef roughness in hydrodynamical models and to monitor the evolution of coral reef systems in the global change context.
(Earth Surface Processes and Landforms. vol. 45, n° 0197-9337, pp. 3042-3054, 22/04/2026)
SIAME, UPPA, MIO, IRD, AMU, INSU - CNRS, UTLN, CNRS, INSU - CNRS, UM, CNRS, UA, CEREGE, IRD, AMU, CdF (institution), INSU - CNRS, CNRS, INRAE, IMAGES-Espace DEV, IRD, UPVD, AU, UR, UM, UG, UA, IMAG, UM, CNRS, UM, CNRS, LEMON, Inria, IMAG, UM, CNRS, HSM, IRD, INSU - CNRS, UM, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LabEX CORAIL, IRD, UAG, EHESS, EPHE, PSL, IFREMER, UR, UPF, UNC, UA
Seismo‐Turbidites in Aysén Fjord (Southern Chile) Reveal a Complex Pattern of Rupture Modes Along the 1960 Megathrust Earthquake Segment
Grainsize analysis and end-member modeling of a long sediment core from Aysen Fjord (southern Chile) allows to identify over 25 seismo-turbidites in the last 9,000 years. Considering the shaking intensities required to trigger these turbidites (V1/2-VI1/2), the majority can be related to megathrust earthquakes. Multiple studies in south-central Chile have aimed at finding traces of giant, tsunamigenic megathrust earthquakes leading to the current 5,500-year-long paleoseismological record of the Valdivia segment. However, none of these cover the southern third of the segment. Aysen Fjord allows to fill this data gap and presents the first, crucial paleoseismic data to demonstrate that the 1960 event was not unique for the Valdivia segment, yielding a recurrence rate of 321 116 years in the last two millennia. Moreover, the oldest identified events in Aysen Fjord date back to 9,000 cal years BP and, thus, also extend the regional paleoseismological record in time. We infer a large temporal variability in rupture modes, with successions of full-segment ruptures alternating with partial and cascading ruptures. The latter seems to significantly postpone the occurrence of another full rupture when consecutively occurring in different parts of the segment. Additionally, one outstanding period of seismic quiescence-during which no megathrust earthquake evidence has been found at any paleoseismic site-occurred after a full rupture in AD similar to 745 that presents an unusual uplift/subsidence pattern. Such variability makes it highly speculative to anticipate the rupture mode of the next megathrust earthquake along the Valdivia segment.
(Journal of Geophysical Research : Solid Earth. vol. 125, n° 2169-9313, 22/04/2026)
UGent, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, CLIMAG, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, GEOPS, INSU - CNRS, CNRS, UB
Ecological succession and resilience of plankton recovering from an acute disturbance in freshwater marshes
The increase in extreme events such as storms is one of the major threats that coastal ecosystems will have to face in the near future. In such a context, both maturation and ecological successions processes remain at the core of ecology to better anticipate the changes to ecosystem biodiversity and functions facing environmental stressors. However, these concepts are mainly approached through closed experimental studies that oversimplify the mechanisms. A survey was carried out on a ‘natural’ and open ecosystem subjected to an acute disturbance, i.e. a marine submersion of freshwater drained marshes, occurring after a storm. Plankton biomass, production and taxonomic/functional phytoplankton diversity were followed weekly at four stations over 2 months. Most of the stations were disrupted by this acute disturbance and displayed gradual growth and development, as described in the classical maturation process. The main differences between stations were attributed to the heterogeneity of the communities before the storm, the intensity of the disturbance and the different human actions performed to recover the freshwater environment. The concept of ‘ecological resilience’ was thus better suited than ‘engineering resilience’ for such open systems facing constant fluctuations in environmental drivers. With regard to ecological succession, the more impacted stations were marked by a significant change in taxonomic beta-diversity, with numerous stochastic processes, due to taxa dispersion. They first exhibited a convergence in functional traits due to the increase in nutrient availability drained from the catchment basin and then an increase in divergence when nutrients became limited.
(Science of the Total Environment. vol. 709, n° 0048-9697, pp. 135997, 22/04/2026)
LIENSs, INSU - CNRS, ULR, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UNIMA, DIACT
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
Quasagro - Gestion agronomique des sols et des résidus : quels impacts sur la qualité sanitaire des productions végétales de grande culture ?
En relation avec la qualité sanitaire des produits de la récolte, le projet Quasagro visait à valider des éléments de gestion globale des risques multicontaminants (mycotoxines, éléments-traces métalliques et résidus de pesticides) associés aux facteurs environnementaux et aux pratiques agronomiques en grandes cultures (blé tendre, blé dur et tournesol) par analyse multifactorielle : effets pédoclimatiques, résidus de culture, intrants et apports de matière organique. Il s’est appuyé sur le réseau national de parcelles Quasaprove, renforcé par des essais plein champ existants. Par une approche sans a priori, des modèles statistiques ont été testés sur le blé tendre, à partir de paramètres pédologiques ou climatiques. Aucun modèle ne s’est révélé suffisamment prédictif. Nous avons également cherché si certaines pratiques entraînaient des différences de concentration dans les végétaux. Il est apparu qu’il n’y a pas de différence entre les parcelles labourées et non labourées, en fonction du type de fertilisation, ou en fonction du précédent ou de l’usage d’un CIPAN. Aucune différence n’est apparue non plus entre les parcelles conduites en agriculture biologique ou en agriculture conventionnelle. Quelle que soit la culture, l'équilibre est déterminé par le type de fertilisation. Dans le cas de la fertilisation uniquement azotée (ammonitrate), le bilan est toujours négatif. Dans le cas de la fertilisation organique en agriculture biologique, le bilan est toujours positif et le sol accumule les éléments-traces. Dans le cas de l'agriculture conventionnelle avec fertilisation NPK, le bilan est positif pour l'arsenic, le cadmium et le plomb, et négatif pour le cuivre et le zinc. L’exportation des pailles, qui génère un flux d’exportation relativement faible, ne change pas ces conclusions. Sur les parcelles étudiées, les niveaux de concentration cumulés observés s’échelonnent du sub-ng/g à la centaine de ng/g (ps) dans les sols. Les concentrations cumulées maximales en agriculture biologique sont de l’ordre de la dizaine de ng/g. Par comparaison des itinéraires techniques conventionnel/biologique, les herbicides sont présents de façon marquée en conventionnel et quasi absents en biologique ; les fongicides sont présents en biologique à des concentrations supérieures aux limites de quantification et les niveaux de fongicides sont relativement similaires en biologique et en conventionnel dit raisonné. La présence notable de pesticides rémanents (e.g. époxiconazole dont les derniers traitements dataient de plusieurs années) a également été mise en évidence. Le devenir des pesticides dans l’environnement est conditionné par leur comportement dans les sols. L’interaction entre divers processus régissant leur devenir (rétention, dégradation, transfert) va conditionner entre autres leur persistance (ou rémanence). Plus particulièrement, les processus de dégradation des pesticides contribuent à diminuer cette persistance. Le potentiel de biodégradation microbienne dépend ainsi des molécules (toxicité intrinsèque, capacité d’adsorption au sol), de facteurs pédoclimatiques (type d’argiles, matière organique, température et humidité), de facteurs microbiens tels que la biomasse globale et la présence de micro-organismes adaptés à certaines molécules (ex: isoproturon, 2,4-D) et des historiques de traitement (fréquence de traitement). D’une manière générale, il semble que les systèmes bas intrants favorisent l’activité microbienne des sols, par rapport aux systèmes conventionnels.
(Innovations Agronomiques. vol. 79, n° 1958-5853, pp. 121-146, 22/04/2026)
Acta, UMR ISPA, Bordeaux Sciences Agro, INRAE, ECOSYS, INRAE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, MycSA, INRAE, ITAB, ARVALIS
Hydroclimate change in subtropical South Africa during the mid-Piacenzian Warm Period
The mid-Piacenzian Warm Period (mPWP, 3.264–3.025 Ma) of the Pliocene epoch has been proposed as an analog for future climate scenarios. Disagreement between the paleoenvironmental reconstruction and model simulations of the climate in subtropical regions for this period suggests that more investigation of the subtropical climate variability of the mPWP is needed. This study presents pollen, microcharcoal and benthic foraminifera oxygen isotope records generated from marine sediment cores of International Ocean Discovery Program (IODP) Exp. 361 Site U1479 from the Cape Basin offshore of South Africa for the period between 3.337 and 2.875 Ma. With an average sample resolution of 3 ka, this record represents the highest-resolution record of mPWP vegetation change from the region. Our results indicate that the vegetation during the mPWP was dominated by fynbos (species-rich heathy vegetation in the Cape Floristic Region) with variable proportions of Ericaceae. Moreover, the development of the Afrotemperate forest (tall, multilayered indigenous forests in South Africa) reflects shifts in the amounts of precipitation between winter and summer in the year-round rainfall zone. The vegetation variation is probably influenced by the latitudinal insolation gradient in response to precession forcing. Several glacials depicted by the benthic foraminifera oxygen isotope record were characterized by lower percentage values of Restionaceae, higher percentage values of ericoid fynbos and Afrotemperate forest. These events correspond well with cooler SE Atlantic sea surface temperatures driven by interactions of both atmospheric and oceanographic processes. The cooler sea surface temperatures attributed to Antarctic ice sheet expansion, reduced Agulhas leakage (heat and salt transfer from the Indian Ocean to the Atlantic Ocean) and/or intensified southern Benguela upwelling, resulted in less precipitation in the winter rainfall zone of South Africa.
(Quaternary Science Reviews. vol. 249, n° 0277-3791, pp. 106643, 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
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
Acute Toxicity of Sodium Chloride, Nitrates, Ortho-Phosphates, Cadmium, Arsenic and Aluminum for Juveniles of the Freshwater Pearl Mussel: Margaritifera Margaritifera (L.1758)
The freshwater pearl mussel (FWPM) Margaritifera margaritifera (L.1758) is critically endangered in Europe and ecotoxicological studies on the species are scares. Here, 96 h acute toxicity tests were conducted at 16 °C with sodium chloride (NaCl), nitrates (NO3−), ortho-phosphates (PO43−), cadmium (Cd), aluminum (Al) and arsenic (As) on 13- to 28-month-old post-parasitic juveniles. The experimental protocol was developed according to conditions described in a standard guide and was modified in order to assess toxicity thresholds for the Dronne River. Results showed that juveniles were tolerant to concentrations of Al, Cd, As, PO43−, NO3− and NaCl, largely higher than those found in the Dronne river, since 96 h EC50s (effective concentrations) were >954 µg/L for Al; >110 µg/L for Cd; >127 µg/L for As; >5.01 mg/L for PO43−; between 1000 and 1500 mg/L for NO3− and were 1.19 and 1.33 g/L for NaCl. Moreover, the use of a substrate in experiments was found not to affect juvenile responses and younger juveniles seemed more sensitive than older individuals. This study thus provides new data about the tolerance of FWPM to environmental pollution and suggests that pollutant concentrations in the river are significantly lower than levels affecting them.
(Environments. vol. 7, n° 2076-3298, pp. 48, 22/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS