On the coupling of wave and three-dimensional circulation models: Choice of theoretical framework, practical implementation and adiabatic tests
Many theoretical approaches and implementations have been proposed for the coupling of the three-dimensional ocean circulation with waves. The theoretical models are reviewed and it is shown that the formulation in terms of the quasi-Eulerian velocity circumvents the essential difficulty of alternative formulations for the Lagrangian mean velocity. Namely, models based on this Lagrangian velocity require an estimation of wave-induced motions to first order in the horizontal gradients of the wave field in order to estimate the vertical flux of wave pseudo-momentum. So far, only three-dimensional wave models have been able to provide these estimates, and all published theories based on the simpler Airy theory are not consistent at the leading order, because they ignore or incorrectly estimate the vertical momentum flux. With an adiabatic example on a sloping bottom it is shown that this inconsistency produces very large spurious velocities. These errors are independent of the slope for the inviscid case, and are still significant when a realistic vertical mixing is applied. A quick diagnostic of the potential accuracy of a theoretical model is the vertical profile of the wave-induced forcing terms: if it is not uniform over depth in adiabatic conditions then it will produce spurious artificial flow patterns in conditions with shoaling waves. Although conceptually more challenging, the quasi-Eulerian velocity theories only introduce minor modifications of the solution procedure for the standard primitive equations: a modification of the surface boundary condition for the mass conservation, the addition of the Stokes drift in the tracer advection equations, and sources of momentum and turbulent kinetic energy with associated surface and bottom fluxes. All the necessary modifications of primitive equation models are given in detail. This implementation is illustrated with the MARS3D model, which passes the test of the adiabatic shoaling waves.
(Ocean Modelling. vol. 40, n° 1463-5003, pp. 260 - 272, 11/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LOS, IFREMER, DYNECO, IFREMER
Refining our knowledge of the Messinian salinity crisis records in the offshore domain through multi-site seismic analysis
The Messinian salinity crisis (MSC) is characterized by gigantic erosion that remodels the margins while a thick, essentially evaporitic and detrital, sedimentary sequence forms in the deep basins. Based on recent (MAURESC, 2003) and earlier (MESEA 1, 1990; MAGIRAA, 1996; GEOBREST, 2002) seismic reflection data, this work brings to light the record of the MSC on the Provençal margin, which has until now been rarely explored from this perspective. Beyond its strictly regional interest, this study fits into a larger synthesis of MSC seismic markers in the Mediterranean and Black Sea marine domain [Lofi et al., 2011] and employs the new nomenclature established on this occasion. The results obtained reveal a Messinian detrital body (CU unit) of 625 metres maximum thickness at the foot of the margin, accumulating at the mouths of the principal canyons. Its form, facies and extension assimilate it to clastic fans, fed by subaerial erosion linked to the MSC. The relative geometry of CU and the Messinian units MU and UU deposited in the deep basin give indications to their chronostratigraphic relations. The deposition of the CU unit is posterior to the basal part of the mobile unit consisting of halite (MU), but contemporary to its top. These results agree with the recent scenarii, which propose that the precipitation of MU in the basin began early, during the lowering of the sea level, and ended at a low level during the MSC [Blanc, 2000; Martin et al., 2001; Sage et al., 2005; Ryan, 2009]. The UU unit surmounts MU and is subdivided into two sub-units with perceptibly different seismic facies : UU1 at the base and UU2 at the summit. UU1 could correspond to a unit containing more halite and/or more clastic material than UU2. The UU1 sub-unit could be partially contemporary to the CU unit. Concerning salt tectonics and its markers, three structural provinces have been evidenced in the sector of study, respectively : an upslope domain in extension (normal faults), an intermediary domain in translation (tabular MU) and a downslope domain in contraction (salt diapirs). These domains are directly linked to the gravity spreading and/or gliding of the brittle sedimentary cover formed by the CU, UU and Plio-Quatenary units and of the mobile level, MU. In the study area, a close relation between the distribution and thickness of CU and salt tectonics has additionally been evidenced at the mouths of the large Messinian canyons, being best expressed where CU is thick.
(Bulletin de la Société Géologique de France. vol. 182, n° 0037-9409, pp. 163-180, 11/04/2026)
UAG, INSU - CNRS, UM, CNRS, GEOAZUR 6526, IRD, UPMC, UNS, INSU - CNRS, UniCA, CNRS, LDO, INSU - CNRS, UBO EPE, CNRS, IMAGES, UPVD, LMTG, UT3, Comue de Toulouse, CNRS, BRGM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, iSTeP, UPMC, CNRS
Acquisition de tolérance par les biofilms périphytiques exposés aux pesticides en mélange
Dans notre étude, l'impact de pesticides en mélange est évalué sur des communautés périphytiques de rivière provenant d'un site exempt de contamination en pesticides (station amont) et d'un site subissant des pollutions chroniques en pesticides (station aval) à travers l'utilisation d'extraits d'échantillonneurs passifs de type POCIS (Polar Organic Chemical Integrative Sampler). Le rendement photosynthétique optimal (Fv/Fm), la fluorescence de chlorophylle a (chla), le poids sec (PS) et la matière sèche sans cendre (MSSC) sont suivis pendant les 14 jours d'expérimentation. D'autre part, la tolérance acquise des communautés initiales puis l'évolution de cette tolérance en fonction de la levée ou du maintien de la « pression toxique » sont évaluées face aux extraits de POCIS (EP). A J14, une diminution significative du PS et de la MSSC chez les biofilms avals exposés aux EP par rapport aux biofilms avals non exposés est observée ainsi qu'une augmentation significative de la chla pour les biofilms amont exposés aux EP à J7 et J14 par rapport aux biofilms amont non exposés. Au temps initial, les biofilms provenant des stations amont et aval présentaient des niveaux de tolérance différents, avec des CE25 (Fv/Fm) de 0.06±0.01 et 0.48±0.14EP respectivement. Après 14 jours d'exposition aux EP, une différence de sensibilité pour les concentrations les plus élevées est apparue au regard du Fv/Fm et de la chla entre les biofilms avals exposés ou non aux EP. Les 3 concentrations les plus élevées entrainent une inhibition significative du Fv/Fm pour les biofilms non exposés aux EP (51±13, 21±15 et 15±10% respectivement, % du contrôle), alors que seules les 2 concentrations les plus élevées ont un impact sur Fv/Fm pour les biofilms exposés aux EP (43±2 et 25±3% respectivement, % du contrôle). Pour la concentration la plus élevée, la quantité de chla des biofilms exposés aux EP est significativement plus importante par rapport aux non exposés (222±7.53 et 204±5.43 % du contrôle respectivement). Les différents descripteurs testés révèlent un impact des EP sur les capacités photosynthétiques des communautés (chla, Fv/Fm) ainsi qu'un impact sur la croissance globale du biofilm (PS, MSSC). L'important écart de tolérance initiale entre les biofilms amont et aval répond bien au concept PICT développé par Blanck et al. en 1988, de plus les différences dans l'évolution de la tolérance face au maintien ou non de l'exposition aux pesticides sur 14 jours permettent d'appréhender les réponses des communautés naturelles face à un changement de pression de contamination. Notre étude souligne donc l'intérêt de l'utilisation des POCIS combinée aux approches de type PICT dans le domaine de l'écotoxicologie ainsi que leur potentiel dans le cadre de développements de nouveaux outils de diagnostic de la qualité des eaux.
(pp. 1, 11/04/2026)
UR REBX, CEMAGREF, UR MALY, CEMAGREF, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Owen Fracture Zone: The Arabia-India plate boundary unveiled
We surveyed the Owen Fracture Zone at the boundary between the Arabia and India plates in the NW Indian Ocean using a high-resolution multibeam echo-sounder (Owen cruise, 2009) for search of active faults. Bathymetric data reveal a previously unrecognized submarine fault scarp system running for over 800 km between the Sheba Ridge in the Gulf of Aden and the Makran subduction zone. The primary plate boundary structure is not the bathymetrically high Owen Ridge, but is instead a series of clearly delineated strike-slip fault segments separated by several releasing and restraining bends. Despite an abundant sedimentary supply by the Indus River flowing from the Himalaya, fault scarps are not obscured by recent deposits and can be followed over hundreds of kilometres, pointing to very active tectonics. The total strike-slip displacement of the fault system is 10-12 km, indicating that it has been active for the past ~3 to 6 Ma if its current rate of motion of 3±1 mm yr−1 has remained stable. We describe the geometry of this recent fault system, including a major pull-apart basin at the latitude 20°N, and we show that it closely follows an arc of small circle centred on the Arabia-India pole of rotation, as expected for a transform plate boundary.
(Earth and Planetary Science Letters. vol. 302, n° 0012-821X, pp. 247-252, 11/04/2026)
iSTeP, UPMC, CNRS, LGENS, INSU - CNRS, CNRS, ENS-PSL, PSL, GEOAZUR 6526, IRD, UPMC, UNS, INSU - CNRS, UniCA, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Application of a data-model assimilation method to a 3D surf zone sandbar physical experiment
Video imagery recently arose as a low-cost alternative to direct measurement to estimate wave characteristics and then tackle the lack of actual updated bathymetries hydro-morphodynamic coupled numerical models typically face. Nonlinearities that are ubiquitous over complex three-dimensional surfzone sandbars are a key problem for observation relevance, and feed an increasing need of local wave information. Therefore, a close interaction between video imagery and modeling is highly required through observation assimilation. In this paper, we explore two bathymetry inversion methods related to an original experiment on nature-like beaches. Wave celerity was first video-estimated and depth inversion was performed to quantify the underlying bathymetry. While existing methods were previously tested over rather alongshore-uniform barred beaches, here we show that the efficiency of such method strongly decreases with increasing beach alongshore non-uniformity. A data-model assimilation, based on a Kalman filter, was further developed and applied to our experimental study using bathymetric data that derived from wave celerity estimates. Analytically set Gaussian-type covariance matrices were inverted to provide local correction. The method shows promising skills to correct bathymetry with the single source of bathymetric video proxy and now required further in-depth improvement.
(Journal of Coastal Research. vol. SI 64, n° 0749-0208, pp. 976-980, 11/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEGI, UJF, Grenoble INP, CNRS
The ECORS-Truc Vert'08 nearshore field experiment: presentation of a three-dimensional morphologic system in a macro-tidal environment during consecutive extreme storm conditions
A large multi-institutional nearshore field experiment was conducted at Truc Vert, on the Atlantic coast of France in early 2008. Truc Vert'08 was designed to measure beach change on a long, sandy stretch of coast without engineering works with emphasis on large winter waves (offshore significant wave height up to 8 m), a threedimensional morphology, and macro-tidal conditions. Nearshore wave transformation, circulation and bathymetric changes involve coupled processes at many spatial and temporal scales thus implying the need to improve our knowledge for the full spectrum of scales to achieve a comprehensive view of the natural system. This experiment is unique when compared with existing experiments because of the simultaneous investigation of processes at different scales, both spatially (from ripples to sand banks) and temporally (from single swash events to several spring-neap tidal cycles, including a major storm event). The purpose of this paper is to provide background information on the experiment by providing detailed presentation of the instrument layout and snapshots of preliminary results.
(Ocean Dynamics. vol. 61, n° 1616-7341, pp. 2073-2098, 11/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LASAGEC, UPPA, LEGI, UJF, Grenoble INP, CNRS, IMAU, LSEET, INSU - CNRS, UTLN, CNRS, SHOM, OASU, UB, INSU - CNRS, ULR, CNRS, INRAE, IMAGES, UPVD, BRGM
Glacial-interglacial vegetation dynamics in South Eastern Africa coupled to sea surface temperature variations in the Western Indian Ocean
Abstract. Glacial-interglacial fluctuations in the vegetation of South Africa might elucidate the climate system at the edge of the tropics between the Indian and Atlantic Oceans. However, vegetation records covering a full glacial cycle have only been published from the eastern South Atlantic. We present a pollen record of the marine core MD96-2048 retrieved by the Marion Dufresne from the Indian Ocean ∼120 km south of the Limpopo River mouth. The sedimentation at the site is slow and continuous. The upper 6 m (spanning the past 342 Ka) have been analysed for pollen and spores at millennial resolution. The terrestrial pollen assemblages indicate that during interglacials, the vegetation of eastern South Africa and southern Mozambique largely consisted of evergreen and deciduous forests. During glacials open mountainous scrubland dominated. Montane forest with Podocarpus extended during humid periods was favoured by strong local insolation. Correlation with the sea surface temperature record of the same core indicates that the extension of mountainous scrubland primarily depends on sea surface temperatures of the Agulhas Current. Our record corroborates terrestrial evidence of the extension of open mountainous scrubland (including fynbos-like species of the high-altitude Grassland biome) for the last glacial as well as for other glacial periods of the past 300 Ka.
(Climate of the Past. vol. 7, n° 1814-9324, pp. 1209-1224, 11/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
The 7–13 March 2006 major Saharan outbreak: Multiproxy characterization of mineral dust deposited on the West African margin
Mineral dust deposits were collected at Mbour, Senegal, throughout the spring of 2006 and especially during the well‐documented March 7–13 large Saharan dust outbreak. During this 7‐day period, significant changes in mass flux, grain‐size, clay mineralogy and Sr and Nd isotopic compositions were recorded, indicating distinct provenances for the dust transported and deposited during and outside the event. All these terrigenous proxies, as well as freshwater diatom taxa, also showed significant temporal variations during the outbreak, implying contributions from at least two different provenance regions. Tri‐dimensional back‐trajectories and satellite imaging enabled us to link those distinct signatures to regions increasingly to the southeast within a large area covering Mauritania, Mali and southern Algeria, identified by the Total Ozone Mapping Spectrometer (TOMS) as the main source of the prominent winter/spring plume over the tropical Atlantic. The multiproxy characterization of the March 7–13 dust fall therefore enables us to typify the terrigenous signature of two different regions supplying dust off West Africa, and provide valuable clues for the interpretation of Northeastern Tropical Atlantic Ocean dust sedimentary records in terms of changes in provenance regions and transport systems. Additionally, because dust deposition data are scarce, flux and grain size data obtained in this study, among other parameters such as clay assemblages, provide important constraints for atmospheric transport models and dust deposition budget estimates in this area.
(Journal of Geophysical Research: Atmospheres. vol. 116, n° 2169-897X, pp. D18210, 11/04/2026)
LOG, INSU - CNRS, ULCO, CNRS, IRD [Ile-de-France], CNRS, MPIC, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, NIOZ, LOA, INSU - CNRS, CNRS, LISA (UMR_7583), INSU - CNRS, UPD7, UPEC UP12, CNRS, IMAGO
Presence of Palaemon macrodactylus in a Europe estuary: evidence for a successful invasion of the Gironde (SW France)
Palaemon macrodactylus, an exotic shrimp native to the northwest Pacific Ocean, has been recorded in many estuaries along the Atlantic coast of Europe since the late 1990’s. In this study, a regular monthly survey, held since 1992 of the middle section of the Gironde estuary, revealed this species’ rapid and full colonization of the system since its appearance in samples during summer 1998. In the Gironde, the population of P. macrodactylus is self-sustaining and the species is now established there. Our study highlights two important elements that might explain its successful colonization: its ability to quickly invade a niche under-exploited by the similar native species and its greater reproductive output. The species’spatio-temporal distribution in relation to environmental variables was studied and compared with that of the native species P. longirostris. The exotic species was shown to mainly inhabit the polyhaline and mesohaline section of the estuary, which are sections generally under-exploited by females of the native species. Furthermore, fecundity analysis and larval abundance survey results revealed a higher potential fecundity and a greater proportion of larvae and juvenile stages for P. macrodactylus in the natural environment.
(Aquatic Invasions. vol. 6, pp. p. 301 - p. 318, 11/04/2026)
UR EPBX, CEMAGREF, UR MALY, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
In situ giant clam growth rate behavior in relation to temperature : a one-year coupled study of high-frequency noninvasive valvometry and sclerochronology
The life history of 15 giant clams, Hippopus hippopus, was studied in situ in the southern lagoon of New Caledonia; growth rate and animal behavior were studied both by sclerochronology and high-frequency noninvasive (HFNI) valvometry. Electrodes glued on each valve of each specimen recorded the shell-gaping behavior at 0.6-Hz frequency. A nonparametric regression model was used to model clam behavior. The daily increment thickness in the inner layer of five representative clams was measured. H. hippopus has its valves open during the day and partly closed during the night all year round, and shell growth is continuous. The cumulative growth using both techniques was similar, as was the mean daily thickness increment. The occurrence of one increment per day in H. hippopus shell was measured by valvometry. The five sclerochronological profiles were highly similar. Shell growth was significantly correlated to rising sea surface temperature (SST), up to 27 degrees C. At the solar maximum, gaping behavior and increment thickness became erratic. SST- and solar irradiance-related stress could be related to physiological oxidative stress triggered by zooxanthellae symbionts. In the present context of globally increasing SST, our data indicate that the giant clams H. hippopus could live beyond their thermal comfort limits in summer in New Caledonia.
(Limnology and Oceanography. vol. 56, n° 0024-3590, pp. 1940-1951, 11/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LOCEAN, IPSL, ENS-PSL, PSL, UVSQ, UPMC, CEA, INSU - CNRS, X, IP Paris, CNES, CNRS, MNHN, IRD, UPMC, INSU - CNRS, CNRS, LMBA, UBS, UBO EPE, CNRS