Beach cusp dynamics on a reflective beach
Beach cusps are common feature of steep reflective and intermediate beaches. However very few observations reported double coupled cusp systems. Here we present a data set of observations of a beach exhibiting two sets of beach cusps. Data were collected at Grand Popo Beach (Benin, West Africa) in February 2013. Daily topographic survey along a 380m long stretch of shore allowed observing the dynamic of the two set of beach cusps. At the beginning of the field survey, we clearly observe two sets of cusps : the upper beach cusps system is relatively asymetric with a typical wavelength of about 45 m while the lower beach cusps system is relatively symmetric with a typical wave length slightly shorter (about 35 m). After two days, we measured the total destruction of the lower set of beach cusps while the upper set of beach cusps was only partially des tructed. Data suggest that destruction of the lowerbeach cusp system may be related to persistent accretions conditions and/or calm conditions but probably also to the transition from wave- driven circulation dominated by weak alongshore currents with flash and swash rips, to a second period characterized by dominant longshore current further increasing in speed, and rare swash rips. On the other hand the disappearance of the western upper beach cusp might be related to an accretion pattern and to the merging of two individual features. Our observations, consistent with previous works, suggest that beach cusps certainly arise as a result of some combination of erosion and accretion.
(Journal of Coastal Research. vol. SI 70, n° 0749-0208, pp. 669-674, 26/06/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ECOLA, LEGOS, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS, LEGOS, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS, UAC
Dynamics of coarse particulate matter in the turbidity maximum zone of the Gironde Estuary
There is a lack of studies devoted to coarse particulate matter (CPM) in estuaries, although this fraction can disturb activities that filter large volumes of water, such as industrial or fishery activities. In the macrotidal and highly-turbid Gironde Estuary, a monthly sampling of CPM was performed in 2011 and 2013 at two stations in the Turbidity Maximum Zone (TMZ) to understand its seasonal, tidal and hydrological dynamics. Regardless of the season and station, low quantities of CPM (few g m3) were observed in comparison with suspended particulate matter (several 103 g m3). The highest concentrations were consistently recorded in bottom waters and at the upstream station. Whereas there is no clear link between the CPM present in the column water and spring or neap tides, an increase in the CPM size has been identified at the two stations after a flood event, fact potentially critical regarding filtering functioning of estuarine activities.
(Comptes Rendus. Géoscience. vol. 346, n° 1631-0713, pp. 28-36, 26/06/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, EDF [E.D.F.], UR EABX, IRSTEA
Effect of Low-Dose Cadmium Exposure on DNA Methylation in the Endangered European Eel
There is increasing evidence that epigenetics can play a key role in the etiology of diseases engendered by chronic pollutant exposure. Although epigenetics has received significant attention in the field of biomedicine during the last years, epigenetics research is surprisingly very limited in ecotoxicology. The aim of the present study was to investigate the possible effects of low-dose cadmium exposure on the DNA methylation profile in a critically endangered fish species, the European eel. Eels were exposed to environmentally realistic concentrations of cadmium (0.4 and 4 μg•L −1) during 45 days. The global CpG methylation status of eel liver was determined by means of a homemade ELISA assay. We then used a methylation-sensitive arbitrarily primed PCR method to identify genes that are differentially methylated between control and Cd-exposed eels. Our results show that cadmium exposure is associated with DNA hypermethylation and with a decrease in total RNA synthesis. Among hypermethylated sequences identified, several fragments presented high homologies with genes encoding for proteins involved in intracellular trafficking, lipid biosynthesis, and phosphatidic acid signaling pathway. In addition, few fragments presented high homologies with retrotransposon-like sequences. Our study illustrates how DNA methylation can be involved in the chronic stress response to Cd in fish.
(Environmental Science and Technology. vol. 48, n° 0013-936X, pp. 797-803, 26/06/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Etude intégrée de l’effet des apports amont et locaux sur le fonctionnement de la Garonne estuarienne (ETIAGE) : Addendum année 4 Avril 2013 - Mars 2014
Le programme ETIAGE a été mis en place avec pour objectif de répondre aux questions suivantes : que représentent les apports des effluents de la Communauté Urbaine de Bordeaux (CUB) par rapport à ceux venant de l’amont en termes de charge organique et de micro-polluants ? Quels rôles sur le devenir des effluents jouent la présence du bouchon vaseux et la stagnation résiduelle des eaux (déplacement net entre mouvement de flot et de jusant) au niveau de l’estuaire fluvial amont en période d’étiage estival ? Réciproquement, à quels moments et jusqu’où s’étend l’impact de ces effluents sur la qualité des eaux de la Garonne estuarienne ? Quelles incidences des effluents sur le comportement des populations biologiques en place ou migratoires dans la Garonne estuarienne ? Quelle tendance évolutive va connaître l’oxygénation des eaux ? Quel sera l’impact sur le comportement des micro-polluants et des populations biologiques ? Quelles recommandations de gestion pourraient être préconisées à partir de la synthèse des pressions exercées sur les eaux de la Garonne estuarienne ? Le programme est divisé en 5 axes, dont les bilans de travail sont présentés axe par axe.
(pp. 152, 26/06/2026)
UR EABX, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Quantification of MTE in surface sediments of Morbihan Coast (South Brittany, France): A preliminary approach for determination of sources and dynamics
The Morbihan Coast (South Brittany, France) has an intense coastal activity: farming, industry, urban habitation runoff , yachting and transportation. In the past centuries, tin mining industry was also developed. These different factors may introduce metal trace elements (MTE) into the marine environment at toxic concentration levels. This pollution can particularly affect the oyster production, widely developed in the area. Monitoring MTE in surface sediments at high spatial resolution has been programmed to assess pollutants and their sources in two of the major Morbihan coastal systems concerned with oyster farming, and where available information on MTE impact and sediment quality is limited: the Bay of Quiberon, partly protected from the open ocean by the Quiberon Peninsula and several islands, mostly sandy (coarse to fine, with a significant shelly fraction), with water depths shallower that 25 m, and the Gulf of Morbihan, a shallow depth (less than 5 m, apart from the two paleoriver beds), semi-enclosed, estuarine system with very coarse sand to fine mud, mostly distributed by a strong tidal current system. Fifty two surface sediment samples were collected in April 2013 to characterize the MTE spatial distribution through the salinity and pollution gradients, from the small local rivers and harbor areas to the open marine environments. Analyses cover sedimentological and biogeochemical properties (particulate organic carbon using a LECO-CS-230; MTE using ICP-MS or DMA for Hg). Statistical analyses help to discriminate within the spatial variability the natural (e.g. grain-size effect) and anthropogenic factors. MTE concentrations were also compared to local geochemical background as measured at the bottom of three sediment cores collected in representative sites, for calculating the enrichment index of each MTE and evaluating the degree of sediment contamination. The initial interpretation of the results would indicate a clear distinction between the geochemical gradients linked to natural processes: sediment sources and size fractionation (for example, the relationship between Sr and car-bonate concentration in the sand fraction), and gradients linked to polluting factors, in particular in the harbors and protected arias, probably associated with boat maintenance (with Cu, Zn and Sn concentrations exceeding 100 ppm, up to 300 ppm in isolated places). More detailed statistical analyses and implications will be presented at the conference.
(. vol. 16, 26/06/2026)
LGO, UBS, IFREMER, UBO EPE, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Terrigenous input to a fjord in central Norway records the environmental response to the North Atlantic Oscillation over the past 50 years
During the last century, both earth surface temperature and moisture transport towards high latitudes have increased rapidly. The response of the sub-arctic region to these changes in terms of weathering, transport and delivery of terrigenous material towards the coastal and deep ocean is both complex and poorly understood. Sediments accumulating in fjords offer an excellent opportunity for studying such land–ocean interactions and may provide ultra-high-resolution records of environmental response to short-term climate variability. As a basis for Holocene climate change studies, modern sources, supply and distribution of particular sediment components in the Trondheimsfjord have been investigated and imply lithogenic elements as a promising proxy for terrigenous input and river discharge. To better understand the impact of atmospheric variability on central Norwegian environment, we examine instrumental time series and show that the dominant mode of the atmospheric circulation in the North Atlantic region, the North Atlantic Oscillation (NAO), has a strong impact on river discharge, temperature and precipitation in central Norway. In addition, elemental composition analysis of a short sediment core reveals that from 1959 to 2010, winter precipitation and temperature changes are recorded by changes in the inorganic geochemical composition of Trondheimsfjord sediments. Elemental ratios of Al/Zr and K/Ni in the sediment core MC99-3 show a close relation to small-scale, high frequency climate variations and large-scale changes in the Northern Hemisphere climate. This implies that terrigenous input and related erosional processes in the fjord hinterland are highly sensitive to atmospheric circulation variability in the North Atlantic region. By comparing our results with NAO records derived from ice accumulation rates of Norwegian glaciers, western Greenland ice sheets and river discharge anomalies in the Eurasian Arctic, we show that it is possible to reconstruct the NAO from sedimentary archives in central Norwegian fjords.
(The Holocene. vol. 24, n° 0959-6836, pp. 1411-1418, 26/06/2026)
UiT, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Comparison of sliced inverse regression approaches for underdetermined cases
Among methods to analyze high-dimensional data, the sliced inverse regression (SIR) is of particular interest for non-linear relations between the dependent variable and some indices of the covariate. When the dimension of the covariate is greater than the number of observations, classical versions of SIR cannot be applied. Various upgrades were then proposed to tackle this issue such as RSIR and SR-SIR, to estimate the parameters of the underlying model and to select variables of interest. In this paper, we introduce two new estimation methods respectively based on the QZ algorithm and on the Moore-Penrose pseudo-inverse. We also describe a new selection procedure of the most relevant components of the covariate that relies on a proximity criterion between submodels and the initial one. These approaches are compared with RSIR and SR-SIR in a simulation study. Finally we applied SIR-QZ and the associated selection procedure to a genetic dataset in order to find eQTL.
(Journal de la Société Française de Statistique. vol. 155, n° 1962-5197, 26/06/2026)
IMB, UB, Bordeaux INP, CNRS, CQFD, IMB, UB, Bordeaux INP, CNRS, Inria, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, INSERM, ENSC
Fluid Seepage in Relation to Seabed Deformation on the Central Nile Deep-Sea Fan, Part 2: Evidence from Multibeam and Sidescan Imagery,
On the central Nile deep-sea fan, stratified sediments overlying mass-transport deposits (MTDs) are deformed into slope-parallel seabed undulations associated with fluid seepage. The western part of this system, in water depths of 1,950-2,250 m, is examined using multi-frequency data from hull-mounted and deep-towed swath/profiling systems. Sub-bottom profiles show sub-vertical fluid pipes that terminate both at and below seabed, and gas signatures along fault planes bounding the undulations. Fluid seepage is recorded by high- to intermediate-backscatter patches (HBPs, IBPs) that differ in appearance on multibeam imagery (30 kHz, ≤3 m penetration) and sidescan swaths (170/190 kHz, <0.1 m penetration). Comparison of the two suggests a distinction of (a) buried carbonates (0.1-3 m), (b) broad near-seabed (<0.1 m) carbonate pavements elongate along the undulations, (c) sub-circular areas of seabed seepage up to 300 m across. Four of the latter have narrower gas flares at their edges rising 400-800 m above seabed. These results are consistent with an evolving system of narrow fluid conduits that support the growth and burial of carbonate pavements, shifting over millennial timescales along linear zones parallel to fault planes rooted in MTDs. Sediment deformation above MTDs is inferred to provide pathways for fluid escape, but migration of gas-rich fluids from depth is likely to have facilitated slope destabilisation
(Advances in Natural and Technological Hazards Research. vol. 37, pp. 141-150, 26/06/2026)
OGS, GEOAZUR 7329, INSU - CNRS, UniCA, CNRS, IRD [Occitanie], IRD, UniCA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IFREMER
Implication of methodological uncertainties for mid-Holocene sea surface temperature reconstructions
We present and examine a multi-sensor global compilation of mid-Holocene (MH) sea surface temperatures (SST), based on Mg / Ca and alkenone palaeothermometry and reconstructions obtained using planktonic foraminifera and organic-walled dinoflagellate cyst census counts. We assess the uncertainties originating from using different methodologies and evaluate the potential of MH SST reconstructions as a benchmark for climate-model simulations. The comparison between different analytical approaches (time frame, baseline climate) shows the choice of time window for the MH has a negligible effect on the reconstructed SST pattern, but the choice of baseline climate affects both the magnitude and spatial pattern of the reconstructed SSTs. Comparison of the SST reconstructions made using different sensors shows significant discrepancies at a regional scale, with uncertainties often exceeding the reconstructed SST anomaly. Apparent patterns in SST may largely be a reflection of the use of different sensors in different regions. Overall , the uncertainties associated with the SST reconstructions are generally larger than the MH anomalies. Thus, the SST data currently available cannot serve as a target for bench-marking model simulations. Further evaluations of potential subsurface and/or seasonal artifacts that may contribute to obscure the MH SST reconstructions are urgently needed to provide reliable benchmarks for model evaluations.
(Climate of the Past. vol. 10, n° 1814-9324, pp. 2237 - 2252, 26/06/2026)
MARUM, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, PALEOCEAN, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, NTOU, NTOU, GEOTOP, UQAM, CAU, CEREGE, IRD, INRA, AMU, CdF (institution), INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Identification of Hg-bearing phases and fluxes in the sedimentary record of laguna del Plata, central Argentina
(Revista Mexicana de Ciencias Geológicas. vol. 31, n° 1026-8774, pp. 104-115, 26/06/2026)
UB, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, SPE, CNRS, Bordeaux INP, UBM