Dynamics of the turbidity maximum zone in a macrotidal estuary (the Gironde, France): Observations from field and MODIS satellite data
Over a 1-year period, field and satellite measurements of surface water turbidity were combined in order to study the dynamics of the turbidity maximum zone (TM) in a macrotidal estuary (the Gironde, France). Four fixed platforms equipped with turbidity sensors calibrated to give the suspended particulate matter (SPM) concentration provided continuous information in the upper estuary. Full resolution data recorded by the moderate resolution imaging spectroradiometer (MODIS) sensors onboard the Terra and Aqua satellite platforms provided information in the central and lower estuary twice a day (depending on cloud cover). Field data were used to validate a recently developed SPM quantification algorithm applied to the MODIS `surface reflectance' product. The algorithm is based on a relationship between the SPM concentration and a reflectance ratio of MODIS bands 2 (near-infrared) and 1 (red). Based on 62 and 75 match-ups identified in 2005 with MODIS Terra and Aqua data, the relative uncertainty of the algorithm applied to these sensors was found to be 22 and 18%, respectively. Field measurements showed the tidal variations of turbidity in the upper estuary, while monthly-averaged MODIS satellite data complemented by field data allowed observing the monthly movements of the TM in the whole estuary. The trapping of fine sediments occurred in the upper estuary during the period of low river flow. This resulted in the formation of a highly concentrated TM during a 4-month period. With increasing river flow, the TM moved rapidly to the central estuary. A part of the TM detached, moved progressively in the lower estuary and was finally either massively exported to the ocean during peak floods or temporary trapped (settled) on intertidal mudflats. The massive export to the ocean was apparently the result of combined favorable environmental conditions: presence of fluid mud near the mouth, high river flow, high tides and limited wind speeds. The mean SPM concentration within surface waters of the whole estuary showed strong seasonal variations but remained almost unchanged on a 1-year-basis. These observations suggest that the masses of suspended sediments exported toward the ocean and supplied by the rivers were almost equivalent during the year investigated (2005). Results show the usefulness of information extracted from combined field and current ocean color satellite data in order to monitor the transport of suspended particles in coastal and estuarine waters. (c) 2008 Elsevier Ltd. All rights reserved.
(Estuarine, Coastal and Shelf Science. vol. 81, n° 0272-7714, pp. 321-332, 10/04/2026)
LOV, INSU - CNRS, SU, CNRS, IMEV, INSU - CNRS, SU, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LOV, OOVM, UPMC, INSU - CNRS, CNRS, UPMC, INSU - CNRS, CNRS
La dimension biogéographique de l'évolution de la Vie.
Le rôle de la composante biogéographique dans les mécanismes de l’évolution biologique fait l’objet de discussions entre les évolutionnistes. Dans ce travail, les idées de Darwin dans le contexte de la biogéographie sont discutées après avoir rappelé le rôle de l’élément géographique dans les processus de spéciation et résumé les notions de base et les modèles théoriques classiques de la biogéographie. Le modèle de Darwin, ou de la dispersion à partir d’un « centre d’origine », fut proposé lorsque les preuves de la mobilité continentale n’étaient pas encore concluantes. Le modèle de la vicariance, qui s’oppose à celui de la dispersion, est maintenant soutenu par la dérive continentale et l’expansion des fonds océaniques. Ces deux modèles classiques de la biogéographie pourraient s’appliquer dans les cas de convergence et divergence biogéographique, en relation avec des changements paléogéographiques
(Comptes Rendus. Palevol. vol. 8, n° 1631-0683, pp. 119-132, 10/04/2026)
CR2P, MNHN, UPMC, CNRS
Sensory organs of Archaeostraca (Phyllocarida, Crustacea).
(Evolution & Development. vol. 11, n° 1525-142X, pp. 225-232, 10/04/2026)
CR2P, MNHN, UPMC, CNRS, LDO, INSU - CNRS, UBO EPE, CNRS
Erosion and impact of human disturbance on sediment transport in the Red River, Vietnam
Mechanical erosion and sediment transfers depend strongly on many natural parameters related to topography, climate and land cover [1]. Additionally, anthropogenic activities may affect sediment supplies to estuaries, deltas and the coastal zone [2]. The Red River (China/Vietnam, A=155 000 km²) is a typical tropical humid river originating from the mountainous area of the Yunnan Province in China. Based on daily discharges (Q) and suspended particulate matter (SPM) concentrations between 1960-2007 at SonTay gauging station (outlet of the river and entry to the Delta) provided by the national institute IMHE-MONRE, the mean annual SPM fluxes was estimated to 90 Mt/yr, corresponding to a sediment yield of 600 t/km²/yr, similar to the Ganges/Brahmaputra system [3], and probably due to same controlling factors. The temporal variability of annual SPM fluxes (ranging from 24 to 200 Mt/yr) is strongly related to the interannual hydrological conditions. However, some years of high water flow did not account for high sediment fluxes, especially after 1989 when the HoaBinh dam was operated. Sediment rating curves (power law-type; SPM=aQb) were fitted for both periods (1960-1989; 1990-2007). The analysis of the pre- and post-1989 sediment rating parameters (a, b) suggests a downshift of a-parameter values after 1989, attributed to decreased sediment supply [4]. A single sediment rating curve derived from 1960-1989 data was used to simulate the annual variability of former sediment delivery, generating excellent cumulative flux estimates (error <-5%). In contrast, applying the same rating curve to the 1986-2007 data resulted in systematic, important (up to 97%) overestimation. This suggests that the HoaBinh dam reduces annual SPM delivery to the delta by half, implying changes in nutrient and contaminant transport.
(Geochimica et Cosmochimica Acta. vol. 13, n° 0016-7037, pp. A260, 10/04/2026)
Bioemco, ENS-PSL, PSL, IRD, INRA, UPMC, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IWMI-SEA, IWMI, CGIAR, SFRI, VAAS, ICH/VAST
Benthic geochemistry of manganese in the Bay of Biscay, and sediment mass accumulation rate
Manganese is a major redox reactive element of benthic metabolism. We have built a database of existing knowledge on the benthic geochemistry of Mn in the Bay of Biscay, in order to comprehensively assess the behaviour of Mn in a variety of environments during early diagenesis. The database contains vertical profiles of particulate and dissolved Mn species of 59 cores collected during 17 cruises between 1997 and 2006 at nine stations positioned between 140 and 4,800 m water depths. At all studied stations, Mn species follow the conventional distribution, where Mn(III,IV) species are enriched in the oxic layer, and dissolved Mn is present in the anoxic sediments. A minor part of Mn-oxides originates from sedimenting particles. The major part is of diagenetic origin, and derives from the oxidation of upward-diffusing dissolved Mn(II). Mn-oxide inventories are higher at the deeper stations than at the shallower ones. This difference cannot be attributed to different sources of sedimenting particles, but it must depend on sedimentation rate and diagenetic processes. At depth, dissolved Mn(II) concentrations are constant. This probably reflects equilibrium with an authigenic Mn(II) phase, which is the ultimate phase into which Mn is fossilized. The Mn content of deeper anoxic sediments is similarly low in all the cores studied, associated with corresponding trends of Mn content in sedimenting particles of the Bay of Biscay. Bioturbation, rather than redox oscillations, can convey Mn(III,IV) species downwards into the anoxic sediments where they are reduced, associated with a peak of dissolved Mn. Because dissolved Mn(II) is re-oxidized when it diffuses towards the oxic layer, the inventory of the diagenetic Mn(III,IV) phase remains at steady state, especially at stations where the oxic layer is thick. It then becomes possible to calculate the residence time of diagenetic Mn(III,IV) particles within the oxic layer, using the upward-directed flux of pore water Mn(II). By applying this residence time to the accumulation of sediments within the oxic layer, we obtain the sediment mass accumulation rate. The values calculated for the sediments of the Bay of Biscay fit well with accumulation rates obtained from radionuclides or sediment traps. The method has also been validated with data collected in other marine sedimentary environments.
(Geo-Marine Letters. vol. 29, n° 0276-0460, pp. 133-149, 10/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LPGN, UN, CNRS, IPGP - UMR_7154, INSU - CNRS, IGN, UR, IPG Paris, CNRS, UPCité
Des biofilms témoins et acteurs du fonctionnement de la rivière
Des biofilms phototrophes complexes (multi espèces) se développent dans certains tronçons de rivière. Ils participent au fonctionnement de la rivière et peuvent être utilisés comme bioindicateurs pour la gestion des cours d'eau.
(pp. 3, 10/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CNRS, UR REBX, CEMAGREF
New core-top Mg/Ca calibration of multiple benthic foraminiferal species: Thermometry of the thermocline water in tropical western Atlantic
(. vol. 11, 10/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UiB, BCCR, BIO / UiB, UiB, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, PALEOCEAN, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, LPGN, UN, CNRS
Spatial heterogeneity in the food web of a heavily modified Mediterranean coastal lagoon: stable isotope evidence
We investigated the food web structure of the Salses-Leucate Lagoon (northwestern Mediterranean) through delta C-13 and delta N-15 analysis of its benthic macrofauna and potential food sources. This lagoon was heavily human-modified during the 1970s, allowing permanent exchange with the open sea and an increase in salinity from that time. As a result, it exhibits a much less marked salinity gradient than the neighbouring lagoon ecosystems, which Suggests a priori that its food web structure is more homogeneous. In this environmental context, we assessed spatial variability in the isotopic composition of non-vagrant macrofauna in Salses-Leucate in relation to degree of connection with the open sea, anthropogenic inputs and the presence of oyster aquaculture. Overall, the main trophic pathway is based on suspended particulate organic matter and sedimented organic matter. However, there were marked spatial differences (at different scales) in both delta C-13 and delta N-15 values of macrofauna, which suggests an important feeding plasticity within each category of primary consumers at a small spatial scale. delta C-13 data showed that the contributions of the different food sources to the diet of primary consumers changed depending on distance from continental inputs, connection with the open sea and local primary producer coverage. Small-scale delta N-15 variability revealed a very localised influence of anthropogenic nitrogen output. Regarding the possible effect of aquaculture, the isotopic ratios of sediment and macrobenthos were not modified underneath the oyster lines with respect to the neighbouring area. Conversely, the isotopic signature of consumers living on the oyster lines contrasted with those living underneath. Therefore, our results suggest that a decoupling exists between the trophic pathways that occur in the water column and on the soft bottom of this shallow water ecosystem.
(Aquatic Biology. vol. 5, n° 1864-7782, pp. 167-179, 10/04/2026)
LEMAR, IRD, IFREMER, UBO EPE, CNRS, LOBB, OOB, UPMC, CNRS, UPMC, INSU - CNRS, CNRS, EFEB, AD2M, SBR, UPMC, CNRS, UPMC, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Treatment of topographic and bathymetric data acquired at the Truc-Vert Beach (SW France) during the ECORS field experiment
(. vol. special issue 56, 10/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, BRGM, L3AB, UB, INSU - CNRS, CNRS, OASU, UB, INSU - CNRS, ULR, CNRS, INRAE, LAB, UB, INSU - CNRS, CNRS, UB
Contrasting intrainterstadial climatic evolution between high and middle North Atlantic latitudes: A close-up of Greenland Interstadials 8 and 12
Three highly resolved pollen and sea surface temperature records from the Iberian margin (36-42°N) reveal the local evolution of vegetation and climate associated with the rapid climatic variability of marine isotope stage 3. The comparison of the climate at these midlatitudes with dD and d excess from Greenland ice cores shows that the north-south climatic gradient underwent strong variations during the long Greenland Interstadials (GIs) 8 and 12. After the Northern Hemispheric rapid warming at the Greenland Stadial (GS)-GI transition, the trend during the first part of the GI is a Greenland cooling and an Iberian warming. This increase of the North Atlantic climatic gradient led to moisture transportation to Greenland from midlatitudes (lightest d excess) and to a drying episode in Iberia. The subsequent temperature decrease in Greenland and Iberia associated with the precipitation increase in the latter region occurred when the major source of Greenland precipitation shifted to lower latitudes (d excess increase).
(Geochemistry, Geophysics, Geosystems. vol. 10, pp. n/a-n/a, 10/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, GLACCIOS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, UB