Towards the evaluation of ecological consequences of hydromorphological evolutions of the Gironde estuary: A preliminary approach combining GIS and hydrodynamics modelling
Estuaries are composed of a mosaic of habitat providing various ecological functions for many biological communities and many goods and services to society. At the interface between continents and oceans, estuaries in general, and particularly large estuaries, are also environments which concentrate important ecological issues but also many environmental climatic and anthropogenic pressures. The Gironde estuary, one of the largest European estuaries, is thus an emblematic case. Historically, it has undergone major evolutions of its hydromorphosedimentary characteristics due to impacts of climate change and human activities. The aim of this work is to assess the ecological consequences of these changes through the study of the evolution of surfaces of estuarine available habitats and the knowledge of ecological functions associated with these habitats. To do this, we propose to combine two approaches: ecological and hydromorphosedimentary. First, work was undertaken to determine, from scientific literature, tolerances and preferences of representative species of the ecosystem for each of the parameters determining estuarine aquatic habitats (depth, salinity, sedimentary facies ...). Thus, combining available map data and results from a hydrodynamic model implemented in the Gironde, we can map the spatial distribution of these species in the estuary using a geographic information system (GIS). Then, we characterized the ecological functions associated with each habitat (eg. nursery role for sole, migration for eels ...). On the other hand, old maps of the environment have been digitized and analysis was undertaken to characterize the evolution of morphology, hydrological and sedimentary dynamics of the estuary in recent decades. The potential distribution maps we obtained allowed defining a kind of ecological potential that can be used as a reference for assessing effects of development issues, management measures or climate change scenarios. Results highlighted small changes in functional habitats distributions but high vulnerability of some of them (nursery grounds).
(pp. 14, 26/06/2026)
UR EPBX, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Impact écotoxicologiques et économiques des phénomènes de sous-oxygénation et de pollution des estuaires sur l'anguille européenne (Anguilla anguilla)?
(pp. 28, 26/06/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IFREMER, UR EPBX, IRSTEA, GREThA, UB, CNRS
Etude intégrée de l’effet des apports amont et locaux sur le fonctionnement de la Garonne estuarienne (ETIAGE) : Rapport année 1 Avril 2010 - Mars 2011 Addendum
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 pour l’année 1, couvrant la période Avril 2010 – Mars 2011. Cet addendum vient en complément du rapport exécutif, volontairement synthétique, présenté pour chacun des axes de recherche. Hormis les recherches menées dans l’axe 1, strictement débutées en Avril 2011, toutes les autres ont commencé avec plusieurs mois de retard (de trois à neuf mois), pour diverses raisons explicitées en introduction du rapport exécutif. Aussi, seuls des documents complémentaires concernant l’axe 1 seront-ils fournis pour cette première année.
(pp. 14, 26/06/2026)
UR EPBX, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Comment on "Productivity Is a Poor Predictor of Plant Species Richness
Adler et al. (Reports, 23 September 2011, p. 1750) reported "weak and variable" relationships between productivity and species richness and dispute the "humped-back" model (HBM) of plant diversity. We show that their analysis lacks sufficient high-productivity sites, ignores litter, and excludes anthropogenic sites. If corrected, the data set of Adler et al. would apparently yield strong HBM support.
(Science. vol. 335, n° 0036-8075, pp. 1441-b, 26/06/2026)
University of Milan, UNIMI, CEBC, INRA, CNRS, Uninsubria, University of Pennsylvania, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Déformations co-sismiques à Cestas-Pot-aux-Pins et Larrusey
(pp. 140-152, 26/06/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LGO, UBS, IFREMER, UBO EPE, CNRS, PACEA, UB, CNRS
Factors influencing the stable carbon isotopic composition of suspended and sinking organic matter in the coastal Antarctic sea ice environment
A high resolution time-series analysis of stable carbon isotopic signatures in particulate organic carbon (δ 13 C POC) and associated biogeochemical parameters in sea ice and surface waters provides an insight into the factors affecting δ 13 C POC in the coastal western Antarctic Peninsula sea ice environment. The study covers two austral summer seasons in Ryder Bay, northern Marguerite Bay between 2004 and 2006. A shift in diatom species composition during the 2005/06 summer bloom to near-complete biomass dominance of Proboscia inermis is strongly correlated with a large ∼10 ‰ negative isotopic shift in δ 13 C POC that cannot be explained by a concurrent change in concentration or isotopic signature of CO 2. We hypothesise that the δ 13 C POC shift may be driven by the contrasting biochemical mechanisms and utilisation of carbon-concentrating mechanisms (CCMs) in different diatom species. Specifically, very low δ 13 C POC in P. inermis may be caused by the lack of a CCM, whilst some diatom species abundant at times of higher δ 13 C POC may employ CCMs. These short-lived yet pronounced negative δ 13 C POC excursions drive a 4 ‰ decrease in the seasonal average δ 13 C POC signal, which is transferred to sediment traps and core-top sediments and consequently has the potential for preservation in the sedimentary record. This 4 ‰ difference between seasons of contrasting sea ice conditions and upper water column stratification matches the full amplitude of glacial-interglacial Southern Ocean δ 13 C POC variability and, as such, we invoke phytoplankton species changes as a potentially important factor influencing sedi-mentary δ 13 C POC. We also find significantly higher δ 13 C POC in sea ice than surface waters, consistent with autotrophic carbon fixation in a semi-closed environment and possible contributions from post-production degradation, biological utilisation of HCO − 3 and production of exopolymeric substances. This study demonstrates the importance of surface water diatom speciation effects and isotopically heavy sea ice-derived material for δ 13 C POC in Antarctic coastal environments and underlying sediments, with consequences for the utility of diatom-based δ 13 C POC in the sedimentary record.
(Biogeosciences. vol. 9, n° 1726-4170, pp. 1137-1157, 26/06/2026)
UEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, BAS, NERC
A two-step process for the reflooding of the Mediterranean after the Messinian Salinity Crisis
The Messinian Salinity Crisis is well known to have resulted from a significant drop of the Mediterranean sea level. Considering both onshore and offshore observations, the subsequent reflooding is generally thought to have been very sudden. We present here offshore seismic evidence from the Gulf of Lions and re-visited onshore data from Italy and Turkey that lead to a new concept of a two-step reflooding of the Mediterranean Basin after the Messinian Salinity Crisis. The refilling was first moderate and relatively slow accompanied by transgressive ravinement, and later on very rapid, preserving the subaerial Messinian Erosional Surface. The amplitude of these two successive rises of sea level has been estimated at ≤500 m for the first rise and 600-900 m for the second rise. Evaporites from the central Mediterranean basins appear to have been deposited principally at the beginning of the first step of reflooding. After the second step, which preceeded the Zanclean Global Stratotype Section and Point, successive connections with the Paratethyan Dacic Basin, then the Adriatic foredeep, and finally the Euxinian Basin occurred, as a consequence of the continued global rise in sea level. A complex morphology with sills and sub-basins led to diachronous events such as the so-called 'Lago Mare'.This study helps to distinguish events that were synchronous over the entire Mediterranean realm, such as the two-step reflooding, from those that were more local and diachronous. In addition, the shoreline that marks the transition between these two steps of reflooding in the Provence Basin provides a remarkable palaeogeographical marker for subsidence studies.
(Basin Research. vol. 24, n° 0950-091X, pp. 125-153, 26/06/2026)
iSTeP, UPMC, CNRS, IPGP, INSU - CNRS, UPD7, UR, IPG Paris, CNRS, LDO, INSU - CNRS, UBO EPE, CNRS, CEREGE, IRD, INRA, AMU, CdF (institution), INSU - CNRS, CNRS, GM, IFREMER, IDES, UP11, INSU - CNRS, CNRS, GeoEcoMar, ICM, CSIC, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ISTO, INSU - CNRS, UO, UT, CNRS, UERJ, LGENS, INSU - CNRS, CNRS, ENS-PSL, PSL, UKIM, BAS, GEOLOGY AND MINING DEPARTMENT, ITÜ, VU, ITÜ, GR, UR, INSU - CNRS, CNRS
Barred-beach morphological control on infragravity motion
A conceptual analysis of the coupling between bars and infragravity waves is performed combining laboratory experiments and numerical modeling. Experiments are carried out in a wave flume with a barred profile. The Boussinesq fully-nonlinear model SERR1D is validated with the laboratory data and a sensitivity analysis is performed next to study the influence on the infragravity wave dynamics of bar amplitude and location, and swash zone slope. A novel technique of incident and reflected motions separation that conserves temporal characteristics is applied. We observe that changing bar characteristics induces substantial variations in trapped energy. Interestingly, a modification of swash zone slope has a large influence on the reflected component, controlling amplitude and phase time-lag, and consequently on the resonant pattern. Variations of trapped infragravity energy induced by changes of swash zone slope reach 25 %. These changes in infragravity pattern consequently affect short-wave dynamics by modifying the breakpoint location and the breaking intensity. Our conceptual investigation suggests the existence of a morphological feedback through the action of evolving morphology on infragravity structures which modulates the action of short-waves on the morphology itself.
(pp. currents.24, 26/06/2026)
LEGOS, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS, PUC, UTFSM, LEGI, UJF, Grenoble INP, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Climatically-controlled siliceous productivity in the eastern Gulf of Guinea during the last 40 000 yr
Opal content and diatom assemblages were analysed in core GeoB4905-4 to reconstruct siliceous productivity changes in the eastern Gulf of Guinea during the last 40 000 yr. Opal and total diatom accumulation rates presented low values over the considered period, except during the Last Glacial Maximum and between 15 000 calendar years Before Present (15 cal. ka BP) and 5.5 cal. ka BP, the so-called African Humid Period, when accumulation rates of brackish and freshwater diatoms at the core site were highest. Conversely, accumulation rates of windblown diatoms exhibited an opposite pattern with higher values before and after the African Humid Period and greatest values during Heinrich Events, the Younger Dryas and since 5.5 cal. ka BP. Our results demonstrate that siliceous productivity in the eastern Gulf of Guinea was directly driven by the nutrient load from local rivers, whose discharges were forced by precipitation changes over western Equatorial Africa and/or modification of the fluvio-deltaic systems forced by sea level changes. Precipitation in this region is controlled by the West African monsoon which is, in turn, partly dependent on the presence and intensity of the Atlantic Cold Tongue (ACT). Our results therefore suggest that the ACT was weakened, warmer trade winds were less vigorous, and cloud convec-tion and precipitation were greater during the AHP though centennial-to-millennial timescale dry events were observed at ∼10 cal. ka BP, ∼8.5 cal. ka BP and ∼6 cal. ka BP. Conversely , the ACT was more intense, trade winds were more vigorous and African climate was more arid during H1, the Younger Dryas and after 5.5 cal. ka BP into the present.
(Climate of the Past. vol. 8, n° 1814-9324, pp. 415-431, 26/06/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IACT, CSIC, UGR, CAU
Vegetation dynamics in the Northeastern Mediterranean region during the past 23 000 yr: insights from a new pollen record from the Sea of Marmara
Abstract. High-resolution pollen analysis of core MD01-2430 from the Sea of Marmara (40°47.81' N, 27°43.51' E) allows us to reconstruct the vegetation response to climatic changes during the past 23 cal ka in the Northeastern Mediterranean. Variation in mesic/temperate forest cover indicates major climatic shifts connected to Heinrich Stadial 1, Bölling-Allerød, Younger Dryas and to the onset of the Holocene. Pollen–anthropogenic indicator approach was used to recognize human-induced landscape changes in the Sea of Marmara. The pollen-inferred onset of the Holocene occurs at ca. 11.5 cal ka, indicating that the Northeastern Mediterranean region represents a transitional zone where higher moisture availability supported an earlier forest expansion than the borderlands of the Aegean Sea and Black Sea. Two major forest retreats occurred during the Holocene at ca. 5.5 and 2.1 cal ka. The Holocene forest setbacks are in phase with previously published alkenone-inferred sea-surface temperature decreases in the Sea of Marmara reconstructed from the same core. Our new pollen record testifies the sensitivity of Mediterranean forests to changes in moisture availability, which is driven by changes in high-latitude atmospheric processes (North Atlantic Oscillations and/or Siberian High).
(Climate of the Past. vol. 8, n° 1814-9324, pp. 1941-1956, 26/06/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UMR ISEM, Cirad, IRD, EPHE, PSL, UM, CNRS