Use of voltametric solid-state microelectrode for studying the effect of tidal forcing on biogeochemical processes on mudflat of the arcachon bay (France)
(10/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, EDF R&D STEP, EDF R&D, EDF [E.D.F.], LPGN, UN, CNRS, LOBB, OOB, UPMC, CNRS, UPMC, INSU - CNRS, CNRS
Ocean color measurements onboard a jet-ski : consistency for calval exercise of high-resolution satellite imagery?
(. vol. 7150, pp. Vol. 7150, Q1Q10, doi:10.1117/12.805382, 10/04/2026)
CRC, UB, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Last glacial fire regime variability in western France inferred from microcharcoal preserved in core MD04-2845, Bay of Biscay
High resolution multiproxy analysis (microcharcoal, pollen, organic carbon, Neogloboquadrina pachyderma (s) , ice rafted debris) of the deep-sea record MD04-2845 (Bay of Biscay) provides new insights for understanding mechanisms of fire regime variability of the last glacial period in western France. Fire regime of western France closely follows Dansgaard–Oeschger climatic variability and presents the same pattern than that of southwestern Iberia, namely low fire regime associated with open vegetation during stadials including Heinrich events, and high fire regime associated with open forest during interstadials. This supports a regional climatic control on fire regime for western Europe through fuel availability for the last glacial period. Additionally, each of Heinrich events 6, 5 and 4 is characterised by three episodes of fire regime, with a high regime bracketed by lower fire regime episodes, related to vegetational succession and complex environmental condition changes.
(Quaternary Research. vol. 71, n° 0033-5894, pp. 385-396, 10/04/2026)
PACEA, UB, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Imprints of high-salinity water plumes originating from the Red Sea during termination II.
(Palaeogeography, Palaeoclimatology, Palaeoecology. vol. 279, n° 0031-0182, pp. 69-79, 10/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CR2P, MNHN, UPMC, CNRS, IPNO, UP11, IN2P3, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, PALEOCEAN, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA
Field observations of an evolving rip current on a meso-macrotidal well-developed inner bar and rip morphology
The Aquitanian Coast (France) is a high-energy meso-macrotidal environment exhibiting a highly variable double sandbar system. The inner and the outer bar generally exhibit a bar and rip morphology and persistent crescentic patterns, respectively. In June 2007, an intense five-day field experiment was carried out at Biscarrosse Beach. A large array of sensors was deployed on a well-developed southward-oriented bar and rip morphology. Daily topographic surveys were carried out together with video imaging to investigate beach morphodynamic evolution. During the experiment, offshore significant wave height ranged from 0.5 to 3 m, with a persistent shore-normal angle. This paper identifies two types of behavior of an observed rip current: (1) for low-energy waves, the rip current is active only between low and mid tide with maximum mean rip current velocity reaching 0.8 m/s for an offshore significant wave height (Hs) lower than 1 m; (2) for high-energy waves (Hs≈ 2.5–3 m), the rip current was active over the whole tide cycle with the presence of persistent intense offshore-directed flows between mid and high tide. For both low and high-energy waves, very low-frequency pulsations (15–30 min) of the mean currents are observed on both feeder and rip channels. A persistent slow shoreward migration of the sandbar was observed during the experiment while no significant alongshore migration of the system was measured. Onshore migration during the high-energy waves can be explained by different sediment transport processes such as flow velocity skewness, wave asymmetry or bed ventilation. High-frequency local measurements of the bed evolution show the presence of significant (in the order of 10 cm) fluctuations (in the order of 1 h). These fluctuations, observed for both low- and high-energy waves, are thought to be ripples and megaripples, respectively and may play an important but still poorly understood role in the larger scale morphodynamics. The present dataset improves the knowledge of rip dynamics as well as the morphological response of strongly alongshore non-uniform meso-macrotidal beaches.
(Continental Shelf Research. vol. 29, n° 0278-4343, pp. p. 1650-1662, 10/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, BRGM
High frequency sea level fluctuations recorded in the Black Sea since the LGM
This paper presents a 3D geometric interpretation of very high resolution seismic Chirp profiles acquired on the Romanian shelf during ASSEMBLAGE European Project. The results provide a solid record of the Black Sea Last Glacial Maximum (LGM) water level fluctuations. This pseudo-3D seismic interpretation shows that the Black Sea lacustrine shelf deposits form a significant basinward-prograding wedge system. On top of these prograding sequences is a set of sand dunes that delineates a wave cut-terrace like feature around the isobath − 100 m. Landward of this dune field are small depressions containing barkhan-like bodies. The upper part of the last prograding sequence is incised by anastomosed channels which end in the Danube (Viteaz) canyon which are also built on the lacustrine prograding wedge. Ten stratigraphic units were distinguished and correlated with analyses of cores retrieved from this area. The results demonstrate that the first eight sequences represent lacustrine prograding wedges, the ninth sequence is the dune system itself and the tenth is a marine mud drape which covers the entire continental shelf. The lacustrine prograding wedges represent a lowstand deposit characterised by forced regression-like reflectors mapped from the pseudo-3D seismic data. Their hinge point corresponds to the wave erosion surface mapped around − 100 m isobath on the multibeam mosaic. Dated cores give age control on this lowstand period, which lasted from 11 to 8.5 kyr 14C BP as implied by: (1) the continuously dry climatic conditions in the region inferred by high percentages of herbs and steppe elements determined from ASSEMBLAGE cores and, (2) the formation of dunes between 10 and 8.5 kyr 14C BP on the desiccated north-western Black Sea shelf at − 100 m and (3) all of these covered by a marine mud drape confirming that the dune system is no longer active. The buried, anastomosed fluvial channels that suddenly disappear below 90 m depth, and a unique wave-cut terrace between 95 and 100 mbsl on the outer shelf are also consistent with a major lowstand base-level at around − 100 m water depth. Preservation of sand dunes and the occurrence of small, buried incised valleys mark a rapid transgression within less than a century during which ravinement processes related to the water level rise had no time to significantly erode the seafloor.
(Global and Planetary Change. vol. 66, n° 0921-8181, pp. 65-75, 10/04/2026)
IFREMER, UCD, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, PALEOCEAN, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA
IOP from reflectance measurements to obtain the Kd coefficient: application to the Gabon and Congo coastal waters
(. vol. 7459, pp. Vol. 7459, 74590A, doi:10.1117/12.828851, 10/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, SHOM, CRC, UB, CNRS
Evidence from wavelet analysis for a mid-Holocene transition in global climate forcing
A strong mid-Holocene transition has been identified by wavelet analyses in several sea ice cover records from the circum-Antarctic area, ice core records (Taylor dome, Byrd) and tropical marine records. The results are compared with those previously published in a synthesis of North Atlantic records and with 4 new records from the Norwegian and Icelandic seas and from a coastal site in Ireland. These new records confirm the previous pattern for the North Atlantic area, extend this pattern nearly to the Arctic Circle, and include a continental record. We further tested the possibility of extending this scheme using continental records from South America. The Holocene pattern proposed here confirms the importance of external forcing during the Early Holocene (solar activity: 1000 years cyclicity and 2500 years during the entire Holocene), even if the signal is disturbed by meltwater fluxes. The second part of the Holocene is then marked by the gradual appearance of internal forcing (thermohaline circulation around 1500 years), associated with a stabilisation of the signal. Coupling between ocean and atmosphere seems to play a fundamental role in the observed frequencies which vary accordingly in the Atlantic, circum-Antarctic and Pacific areas. The North Atlantic area seems to be the instigator of thermohaline circulation as shown by its sensitivity to meltwater discharges during the Early Holocene, even though each sector is independent with regards to its frequency content (around 1600 years for Atlantic Area; around 1250 years for Antarctica). The Holocene methane pattern, still under debate [Ruddiman, W.F., 2003a. Orbital insolation, ice volume and greenhouse gases. Quaternary Science Review 22, 1597-1629; Ruddiman, W.F., 2003b. The anthropogenic greenhouse era began thousands of years ago. Climatic Change 61, 261-293], could be explained by a more efficient thermohaline circulation around the mid-Holocene with an anthropogenic effect initiated at not, vert, similar2500 BP as shown by the inter-hemispheric gradient.
(Quaternary Science Reviews. vol. 28, n° 0277-3791, pp. 2675-2688, 10/04/2026)
LGGE, OSUG, UJF, Grenoble INP, INSU - CNRS, IRSTEA, USMB [Université de Savoie] [Université de Chambéry], CNRS, INSU - CNRS, CNRS, M2C, UNICAEN, NU, INSU - CNRS, UNIROUEN, NU, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ISTO, BRGM, INSU - CNRS, UO, CNRS, PBDS, INSU - CNRS, CNRS
Influence of the mode of macrofauna-mediated bioturbation on the vertical distribution of living benthic foraminifera : first insight from axial tomodensitometry
We investigated the influence of bioturbation by macrofauna on the vertical distribution of living (stained) benthic foraminifera in marine intertidal sediments. We investigated the links between macrofaunal bioturbation and foraminiferal distribution, by sampling from stations situated on a gradient of perturbation by oyster-farming, which has a major effect on benthic faunal assemblages. Sediment cores were collected on the French Atlantic coast, from three intertidal stations: an oyster farm, an area without oysters but affected by oyster biodeposits, and a control station. Axial tomodensitometry (CT-scan) was used for threedimensional visualization and two-dimensional analysis of the cores. Biogenic structure volumes were quantified and compared between cores. We collected the macrofauna, living foraminifera, shells and gravel from the cores after scanning, to validate image analysis. We did not investigate differences in the biogenic structure volume between cores. However, biogenic structure volume is not necessarily proportional to the extent of bioturbation in a core, given that many biodiffusive activities cannot be detected on CT-scans. Biodiffusors and larger gallery-diffusors were abundant in macrofaunal assemblage at the control station. By contrast, macrofaunal assemblages consisted principally of downward-conveyors at the two stations affected by oyster farming. At the control station, the vertical distribution of biogenic structures mainly built by the biodiffusor Scorbicularia plana and the large gallery-diffusor Hediste diversicolor was significantly correlated with the vertical profiles of living foraminifera in the sediment, whereas vertical distributions of foraminifera and downward-conveyors were not correlated at the station affected by oyster farming. This relationship was probably responsible for the collection of foraminifera in deep sediment layers (N6 cm below the sediment surface) at the control station. As previously suggested for other species, oxygen diffusion may occur via the burrows built by S. plana and H. diversicolor, potentially increasing oxygen penetration and providing a favorable microhabitat for foraminifera in terms of oxygen levels. By contrast, the absence of living foraminifera below 6 cm at the stations affected by oyster farming was probably associated with a lack of biodiffusor and large gallery-diffusor bioturbation. Our findings suggest that the effect of macrofaunal bioturbation on the vertical distribution of foraminiferal assemblages in sediments depends on the effects of the macrofauna on bioirrigation and sediment oxidation, as deduced by Eh values, rather than on the biogenic structure volume produced by macrofauna. The loss of bioturbator functional diversity due to oyster farming may thus indirectly affect infaunal communities by suppressing favorable microhabitats produced by bioturbation.
(Journal of Experimental Marine Biology and Ecology. vol. 371, n° 0022-0981, pp. 20-33, 10/04/2026)
CRELA, IFREMER, ULR, CNRS, BIAF, UA, LIENSs, INSU - CNRS, ULR, CNRS, IRD [Nouvelle-Calédonie], EHF, UCBL, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UN
Praeorbulina-like specimens" in sediments of the Northern Arabian Sea during the last glacial period
(10/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LPGN, UN, CNRS, IFPEN