Volcanism in the Comoros Archipelago, Madagascar, and the East African Rift: What is the link?
The Comoros archipelago located in the western Indian Ocean has been a topic of debate for ca. 50 years regarding its origin. Various mechanisms have been proposed to explain its formation, ranging from the impact of a mantle plume to the development of a plate boundary between the Somalia and Lwandle plates. Determining the timing of the volcanic activity is crucial to understanding the archipelago's origin. Despite recent geochronological studies, the age of the initial volcanic eruptions on the islands remains uncertain due to the difficulty of accessing the earliest lavas. This study uses high-quality seismic reflection profiles and regional stratigraphy to identify the first volcanic series that marked the onset of volcanism on each island of the Comoros Archipelago. Our findings reveal that localized volcanic activity began ca. 32 Ma at Zélée and Geyser banks and Mayotte edifice, the eastern portions of the archipelago, much earlier than previously believed. Volcanism spread across the Comoros archipelago ca. 9-8 Ma, from the northern part of the Mayotte edifice to Mohéli Island in the west. Ca. 4 Ma, volcanic activity occurred on Anjouan Island and the Jumelles seamounts, followed by Grande Comore Island ca. 2 Ma. This progression of ages from east to west indicates a chronological sequence over time. The timing of volcanic activity in the Comoros archipelago is similar to the magmatism evolution documented at Madagascar and along the East African Rift System (EARS). Magmatic activity began in the late Oligocene, followed by quiescence during the middle Miocene, and resumed in the late Miocene, coinciding with widespread deformation along the EARS, including its offshore branches and Madagascar. Our study shows that the regional tectonic control of volcanic activity in the Comoros archipelago began during the early Miocene, thereby suggesting that the Comoros archipelago developed as an offshore branch of the EARS south of the Somalian plate at that time.
(Geosphere. vol. 21, pp. 774-796, 11/07/2026)
iSTeP, INSU - CNRS, SU, CNRS, CY, ITES, ENGEES, UNISTRA, INSU - CNRS, CNRS, EOST, UNISTRA, INSU - CNRS, CNRS, LGENS, INSU - CNRS, CNRS, ENS-PSL, PSL, CNRS, ENS-PSL, PSL, BRGM, LOG, INSU - CNRS, ULCO, CNRS, IRD [Ile-de-France], BGR, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CSTJF, [Total Energies. Anciennement : Total, TotalFina, TotalFinaElf], CEREGE, IRD, AMU, CdF (institution), INSU - CNRS, CNRS, INRAE
The spread of Aoroides longimerus Ren & Zheng, 1996 across the Mediterranean and the Atlantic: genetic diversity, anthropogenic transport, and ecological implications
Accurate knowledge of the global distribution of non-indigenous species (NIS) is essential for understanding their invasion dynamics and for implementing timely management measures. This study reports the first records of the marine amphipod Aoroides longimerus, putatively native to the East Asian coast, in Italy (2018), Spain (2019) and Tunisia (2022) and provides the earliest documented record of the species in its introduced European range (Portugal, 2011). Furthermore, it expands the species' known distribution in mainland Portugal (including the northernmost record), Macaronesia (with first records in the Canary Islands and Madeira), and confirms its presence along the Atlantic coasts of France and the Netherlands. Aquaculture facilities, particularly those associated with oyster farming, are probably the primary vector of introduction, while recreational boating may have contributed significantly to secondary dispersal. In comparison to other exotic amphipods, A. longimerus remains absent from many marinas, ports and/or aquaculture facilities in the Mediterranean Sea and adjacent regions, such as the Red Sea. This suggests that the species may still be in the early stages of expansion, or that its dispersal ability across marinas and ports is more limited than that of other amphipods. The present study, however, highlights several key ecological traits of A. longimerus: (i) it can survive year-round despite seasonal fluctuations, and reach high local densities, (ii) it exhibits strong colonisation capacity, as shown by its rapid establishment on settlement plates, and (iii) it displays opportunistic feeding behaviour, primarily consuming detritus. These characteristics underscore the importance of continuous surveillance and effective communication with stakeholders to prevent further expansion of this species.
(Mediterranean Marine Science. vol. 26, n° 1108-393X, pp. 842 - 859, 11/07/2026)
M2C, UNICAEN, NU, INSU - CNRS, UNIROUEN, NU, CNRS, IUEM, IRD, INSU - CNRS, UBO EPE, CNRS, LEMAR, IRD, IFREMER, UBO EPE, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, AD2M, SU, CNRS, SBR, SU, CNRS, SBR, SU, CNRS, STAMAR, INSU - CNRS, SU, CNRS, FR2424, SBR, SU, CNRS, UMR ISEM, Cirad, IRD, EPHE, PSL, CNRS, UM, ISYEB, MNHN, EPHE, PSL, SU, CNRS, UA
Observations Of Multidecadal Gravel Beach Dynamics From Space
Gravel barrier systems are ubiquitous on mid-and high-latitude coasts and provide vital protection from coastal flooding and coastal erosion. They are highly dynamic systems that exhibit complex responses to hydrodynamic forcing over a range of timescales (hourly-monthly-decadal-centennial). Their dynamics differ greatly from those of sandy beaches yet have received considerably less attention in the literature, particularly at interannual to decadal scales. We use over four decades of satellite-derived shoreline (SDS) data to explore the long-term dynamic of 45 selected gravel systems around the United Kingdom and Ireland. Unlike most large-scale studies, we apply an SDS extraction methodology specifically tailored to gravel beaches to derive the long-term shoreline trends along 1554 shore-normal transects across our sites. Our findings indicate a great variability in shoreline trends, ranging from -4.73 m/year to +10.5 m/year with the majority of transects (62%) remaining stable over the study period (1984 -2023). Overall, 22% of transects showed statistically significant positive trends and 14% negative trends, resulting in an overall +0.36 m/year mean shoreline trend. Large scale climatic forcing seems to have a stronger control on the evolution of gravel nesses with 29% and 26% of transects having an average correlation of -0.36 and -0.34 with North Atlantic Oscillation and Atlantic Oscillation respectively, while open beaches showed the weakest relationship with climate forcing. Importantly, climate forcing did not seem to be a key driver of change in the regions with the highest rates of progradation.
(11/07/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Impacts of neonicotinoids on biodiversity: a critical review
Neonicotinoids are the most widely used class of insecticides in the world but they have raised numerous concerns regarding their effects on biodiversity. Thus, the objective of this work was to do a critical review of the contamination of the environment (soil, water, air, biota) by neonicotinoids (acetamiprid, clothianidin, imidacloprid, thiacloprid, thiamethoxam) and of their impacts on terrestrial and aquatic biodiversity. Neonicotinoids are very frequently detected in soils and in freshwater, and they are also found in the air. They have only been recently monitored in coastal and marine environments, but some studies already reported the presence of imidacloprid and thiamethoxam in transitional or semi-enclosed ecosystems (lagoons, bays and estuaries). The contamination of the environment leads to the exposure and to the contamination of non-target organisms, and to negative effects on biodiversity. Direct impacts of neonicotinoids are mainly reported on terrestrial invertebrates (e.g., pollinators, natural enemies, earthworms) and vertebrates (e.g., birds), and on aquatic invertebrates (e.g., arthropods). Impacts on aquatic vertebrate populations and communities, as well as on microorganisms, are less documented. In addition to their toxicity to directly exposed organisms, neonicotinoid induce indirect effects via trophic cascades as demonstrated in several species (terrestrial and aquatic invertebrates). However, more data are needed to reach firmer conclusions and to get a clearer picture of such indirect effects. Finally, we identified specific knowledge gaps that need to be filled to better understand the effects of neonicotinoids on terrestrial, freshwater and marine organisms, as well as on ecosystem services associated with these biotas.
(Environmental Science and Pollution Research. vol. 32, n° 0944-1344, pp. 2794–2829, 11/07/2026)
ECOSYS, INRAE, RiverLy, INRAE, IFREMER, UMR BAGAP, ESA, INRAE, Institut Agro, VAS, ICE, VAS, UCBL, LBBE, UCBL, VAS, CNRS, LBBE, UCBL, VAS, CNRS, LCE, CNRS, UMLP, UBFC, DECOD, IFREMER, INRAE, Institut Agro, Institut Agro, OFB Service Santé Agri, OFB - DRAS, OFB, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UMR Eco&Sols, Cirad, IRD, INRAE, Institut Agro, UMR MARBEC, IRD, IFREMER, CNRS, UM, EMMAH, AU, INRAE, IMBE, AU, AMU, CNRS, UMay, URAFPA, UL, INRAE, UR HYCAR, INRAE, DEPE, INRAE
Assessment of Beach Slope and Sediment Grain Size Anywhere in the World: Review of Existing Formulae, Integration of Tidal Influence, and Perspectives from Satellite Observations
Grain size and beach slope are critical factors in coastal science and management. However, it is difficult to have information on their distribution everywhere in the world, as most of the coast has never been documented. For many applications, it is essential to have at least a rough estimate when local field measurements are not available. Here, we review the existing prediction formulas relating beach slope to grain size and wave conditions, using publicly available global datasets and comparing them with a benchmark dataset of ground measurements from different authors worldwide. Uncertainties arise from the input parameters, in particular coastal waves, a key parameter of all formulae, but also from empirical coefficients that are undocumented or inaccessible with the global dataset. Despite the recognized importance of tides, they are often overlooked in formulae relating beach slope to sediment grain size. We therefore present an improved formulation that incorporates tidal effects. Although satellites offer a promising alternative to predictive formulae for direct estimation of beach slope and grain size, the current accuracy and methodologies of satellite data are insufficient for global applications. Continued advances in satellite missions, including higher resolution and revisit frequency, as well as new sensors, are essential to improve predictive capabilities and facilitate wider implementation.
(Journal of Marine Science and Engineering. vol. 13, n° 2077-1312, pp. 58, 31/12/2024)
LEGOS, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS, Comue de Toulouse, IRD, UT3, Comue de Toulouse, CNES, CNRS, GET, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, SHOM
Study of intense pulsed light as a new remediation process for pesticides in water using mass spectrometry and ecotoxicological approaches
Pulsed light (PL) technology was investigated as a pesticide removal process. The degradation of 20 pesticides in water was monitored by mass spectrometry and revealed 74 photoproducts. Structure hypotheses were proposed for 47 photoproducts according to their fragmentation, isotopic pattern, and literature data. This work enabled the development of a LC-MS method for the relative quantification of photoproducts and for the absolute quantification of their parent pesticides.
This analytical method was then applied in optimizing the PL parameters. It was demonstrated that increasing voltage and fluence leads to more efficient pesticide degradation, with concentration reduction of 99 % for 14 pesticides. The compound sensitivity seems to be family dependent. Moreover, PL succeeded in degrading the photoproducts themselves.
Acute toxicity tests were performed on the bacteria Aliivibrio fischeri. A significant reduction in toxicity was observed for 10 out of 18 individual pesticides, while no increase was observed for the remaining seven. When applied to a cocktail solution, the toxicity decreased by 7.25-fold between the untreated and the most PL treated solution. This work demonstrates that PL is a promising process for removing pesticides from contaminated water. Further studies are needed to demonstrate the safety of treated wastewater on various trophic links.
(Journal of Hazardous Materials Advances. vol. 17, n° 2772-4166, pp. 100577, 26/12/2024)
OENO, UB, INRAE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Long‐Term Tectono‐Stratigraphic Evolution of a Propagating Rift System, L’Aquila Intermontane Basin (Central Apennines)
AbstractUnderstanding the long‐term tectono‐stratigraphic evolution of active extensional faulting is crucial for unraveling the mode through which continental rifting propagates in space and time. The Pliocene‐Quaternary L’Aquila Intermontane Basin (AIB) in central Apennines offers a natural laboratory for studying a propagating continental rift. Seismicity is related to NW‐SE‐striking normal faults that have been accommodating crustal stretching since the Late Pliocene. Through a multidisciplinary approach integrating field, mineralogical, geochemical (C‐O stable and clumped isotopes) and geochronological (40Ar/39Ar, U‐Th) analyses, this study focuses on the structural connection between the Mount Pettino Fault (MPF) and the Paganica Fault, two active, left‐stepped basin boundary faults of the AIB. A two‐stage tectono‐stratigraphic evolution is proposed during transition from localized to delocalized deformation and fault linkage. Stage‐1 (pre‐Middle Pleistocene) corresponds to nucleation and growth of the MPF, characterized by a ∼5 m thick exhumed fault core, consisting of an isotopically closed cataclasite (T (∆47) ∼33–50°C). Stage‐2 corresponds to the development of a distributed zone of NW‐SE and E‐W extensional faulting in the overlay zone with the Paganica Fault, which is interpreted as a transfer zone linking the basin boundary faults, with maximum long‐term slip rates comparable to those of the connected faults. Structurally controlled circulation of meteoric fluids promoted carbonate veining and travertine formation (T (∆47) ∼8°C). U‐Th carbonate dating of Stage‐2 mineralizations constrains the tectonic activity in the transfer zone at least at ∼182–331 ka. Implications on the tectono‐stratigraphic evolution and on the seismotectonic scenario of the AIB are discussed, providing geodynamic inference at regional scale.
(Tectonics. vol. 43, n° 0278-7407, 23/12/2024)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Field Investigation of Spatio-Temporal Change of Sediment Grain Size and Beach Slope on Wave-Dominated Sandy Beaches
Beach slope is a critical parameter which is usually assumed constant in time and to depend on a single time-invariant median grain size. In the present work, we conducted a three-year intensive in situ bi-yearly monitoring of the 3D distribution (surface and depth across a 50-cm profile) of sediment grain size and beach topography at five sandy beaches in France. These five beaches are representative of the diversity of the metropolitan France beaches in terms of wave climate, tide range, and anthropogenic pressure. Results show that, generally, average sediment grain size and beach slope are finer and more gently sloping at the end of the winter and at the end of the summer, respectively. Results also show a large spatial and temporal variability of both sediment grain size (horizontally and vertically) and of the sandy beach morphology. Sediment grain size shows a consistent vertical gradient, with finer sand closer to the surface. The spatial and temporal patterns of beach slope and beach sediment variability are found to be linked with beach state (dissipative, intermediate, reflective) and anthropogenic pressure at the engineered beaches. Our results also suggest that tide range and modal wave conditions must be considered to improve empirical models linking beach slope and sediment grain size.
(Journal of Coastal Research. vol. 113, n° 0749-0208, 20/12/2024)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Field investigation of spatio-temporal change of sediment grain size and beach slope on wave-dominated sandy beaches
Beach slope is a critical parameter which is usually assumed constant in time and to depend on a single time-invariant median grain size. In the present work, we conducted a three-year intensive in situ biyearly monitoring of the 3D distribution (surface and depth across a 50-cm profile) of sediment grain size and beach topography at five sandy beaches in France. These five beaches are representative of the diversity of the metropolitan France beaches in terms of wave climate, tide range, and anthropogenic pressure. Results show that, generally, average sediment grain size and beach slope are finer and more gently sloping at the end of the winter and at the end of the summer, respectively. Results also show a large spatial and temporal variability of both sediment grain size (horizontally and vertically) and of the sandy beach morphology. Sediment grain size shows a consistent vertical gradient, with finer sand closer to the surface. The spatial and temporal patterns of beach slope and beach sediment variability are found to be linked with beach state (dissipative, intermediate, reflective) and anthropogenic pressure at the engineered beaches. Our results also suggest that tide range and modal wave conditions must be considered to improve empirical models linking beach slope and sediment grain size.
(Journal of Coastal Research. vol. 113, n° 0749-0208, pp. 432-437, 20/12/2024)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, SHOM
Dynamique de la composition de la matière organique particulaire à l’interface continent-océan
La matière organique particulaire (MOP) joue un rôle clef dans le fonctionnement des écosystèmes constituant le continuum aquatique continent-océan. La MOP peut être composée de plusieurs sources produites in situ (phytoplancton, microphytobenthos, macroalgues) ou importées depuis les écosystèmes adjacents (MOP terrestre, MOP anthropique, phytoplancton fluvial, estuarien ou marin). Le long du continuum fluvio-estuarien, les proportions de chaque source dans la composition de la MOP varient au cours des saisons et entre les écosystèmes, fortement influencées par des processus environnementaux (ex. production primaire, sédimentation / remise en suspension, reminéralisation). L’objectif de cette thèse est d’améliorer (1) la caractérisation des signatures isotopiques et élémentaires des sources de MOP, (2) la quantification de la composition de la MOP provenant des fleuves et étant transformée dans les systèmes estuariens, (3) la description de la variabilité spatio-temporelle de la MOP et (4) la compréhension des forçages environnementaux à cette variabilité. Pour ce faire, la composition de la MOP a été estimée à l’aide de modèles de mélanges sur vingt-quatre systèmes fluvio-estuariens tempérés en utilisant les rapports isotopiques et élémentaires du carbone et de l’azote (δ13C, δ15N et C/N), ainsi que de l’hydrogène comme travail méthodologique prospectif (δ2Hn). La variabilité spatio-temporelle de chacune des sources de la MOP a ensuite été liée à des paramètres environnementaux à l’aide de statistiques multivariées pour en déterminer les forçages. Enfin, une comparaison des systèmes au regard de la dynamique de la composition de la MOP a été proposée. Quatre types ont été identifiés parmi les vingt-trois fleuves étudiés : (1) les fleuves à la MOP dominée par du matériel terrestre labile sur le cycle annuel, (2) les fleuves dont la MOP est composée de matériel terrestre labile et de phytoplancton, avec une saisonnalité marquée due à des efflorescences saisonnières ou bien (3) sans saisonnalité marquée, et enfin (4) les fleuves à la MOP composée de MOP terrestre labile, réfractaire et de phytoplancton, en lien avec des conditions saisonnières contrastées. Les cinq estuaires étudiés présentent des dynamiques de compositions de MOP contrastées. Dans l’Elorn et la Leyre la MOP fluviale est remplacée aux faibles salinités par du phytoplancton produit dans l’estuaire toute l’année. L’Aulne fonctionne de manière similaire mais transporte plus en aval la MOP fluviale dans des conditions hivernales. L’estuaire de la Loire présente une MOP composée uniquement de MOP autotrophe, vivante au printemps ou dégradée en hiver. Enfin, l’estuaire de la Gironde présente une MOP dominée par du matériel terrestre réfractaire sur tout le cycle annuel. Le long du continuum fluvio-estuarien, la MOP fluviale présente une composition et une dynamique spatio-temporelle contrastée. Cette MOP apportée par les fleuves voit sa composition ensuite transformée le long de l’estuaire sous une forme réfractaire par dégradation et/ou est additionnée de MOP vivante autotrophe produite in situ.
(17/12/2024)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS