Climate-Caused Abrupt Shifts in a European Macrotidal Estuary
Although many consequences of climate change on marine and terrestrial ecosystems are well documented, the characterisation of estuarine ecosystems specific responses and the drivers of the changes are less understood. In this study, we considered the biggest Southwestern European estuary, the Gironde, as a model of a macrotidal estuary to assess the effects of both large- (i.e., North Atlantic basin-scale) and regional-scale climate changes. Using a unique set of data on climatic, physical, chemical and biological parameters for the period 1978–2009, we examined relations between changes in both the physical and chemical environments and pelagic communities (plankton and fish) via an end-to-end approach. Our results show that the estuary experienced two abrupt shifts (!1987 and !2000) over the last three decades, which altered the whole system. The timing of these abrupt shifts are in accordance with abrupt shifts reported in both marine (e.g., in the North Sea, the Mediterranean Sea and along the Atlantic) and terrestrial (e.g., in European lakes) realms. Although this work does not allow a full understanding of the dynamical processes through which climate effects propagate along the different compartments of the ecosystem, it provides evidence that the dynamics of the largest estuary of Southwest Europe is strongly modulated by climate change at both regional and global scales.
(Estuaries and Coasts. vol. 36, n° 1559-2723, pp. 1193-1205, 22/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LOG, INSU - CNRS, ULCO, CNRS, IRD [Ile-de-France], UR EPBX, IRSTEA
Effets de mélanges environnementalement réalistes de pesticides sur des biofilms naturels ayant des historiques d'exposition différents
Localisée dans la région viticole du Beaujolais (Est de la France), la Morcille est soumise à une pression viticole forte conduisant à la contamination de la rivière par une gamme d'herbicides et de fongicides. L'objectif de cette étude est d'utiliser des extraits d'échantillonneurs passifs pour mettre en évidence les effets de mélanges réalistes de pesticides sur des biofilms naturels avec des antécédents d'exposition diversifiés. Les impacts chroniques et aigus des pesticides en mélange sur les biofilms ont été évalués à l'aide d'extraits de POCIS (Polar Organic Chemical Integrative Samplers) préalablement immergés à l'aval du cours d'eau (site le plus contaminé). Leurs effets sur des communautés issues de l'amont (site de référence) et de l'aval (contaminé) ont été étudiés en canaux artificiels, dans lesquels les biofilms ont été placés dans des conditions non contaminées pendant 13 jours, ou exposés à des extraits de POCIS afin de reproduire une pression toxique réaliste (observée in situ). Après 13 jours d'exposition, des impacts significatifs de la contamination ont été observés sur les paramètres liés à la biomasse, à la croissance et à la physiologie des biofilms. Une diminution significative de la densité de diatomées a été observée pour les biofilms exposés, par rapport aux témoins, quelle que soit l'origine du biofilm. Les analyses taxonomiques ont révélé des impacts des mélange de pesticides sur la composition des diatomées, la structure des communautés amont divergeant avec l'exposition ou non (avec des abondances accrues de Nitzschia palea et Eolimna minima pour la modalité contaminée). Les communautés aval, exposées ou non, se sont avérées présenter une composition, soulignant l'importance des processus d'immigration dans la récupération des assemblages de diatomées. Afin d'évaluer la tolérance initiale de biofilms au mélange de pesticides, des tests de toxicité aiguë ont été réalisés en début d'expérience, révélant une tolérance nettement plus élevée des biofilms originaires du site en aval, par rapport aux biofilms amont. Cette différence de tolérance aux extraits d'échantillonneurs passifs peut s'expliquer par les compositions taxonomiques très différentes selon l'origine du biofilm, elle reflète l'adaptation des communautés par les processus de sélection des espèces et illustre le concept PICT (Blanck et al, 1988.). Nos résultats soulignent des effets des mélange de pesticides marqués sur la croissance du biofilm, la composition diatomique, et sur la tolérance des biofilms naturels aux facteurs auxquels ils sont exposés. Cette étude met en évidence l'utilisation potentielle des extraits d'échantillonneurs passifs, combinés avec des tests de toxicité aiguë, pour l'expérimentation des impacts d'expositions chroniques plus réalistes sur les biofilms naturels, et offre des perspectives d'applications prometteuses pour l'évaluation du risque écologique lié aux pesticides.
(pp. 1, 22/04/2026)
UR REBX, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR MALY, IRSTEA
Occurrence of selected micropollutants in treated wastewater and removal with optimised tertiary treatments
Two tertiary treatments were studied at pilot scale in three different plants. An advanced oxidation processes pilot was tested in two plants with two different upstream treatment processes: a membrane bioreactor and a low load activated sludge followed by a sand filter. An activated carbon pilot was tested in one plant, a low load activated sludge followed by a sand filter and an ozone reactor. 64 micropollutants were analysed in the samples of this study. The tertiary treatments studied, ozone, AOP and activated carbon, were efficient for the removal of most of the micropollutants analysed in this study, except metals.
(pp. 3 p., 22/04/2026)
CIRSEE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR MALY, IRSTEA
Qualité de l’eau : chapitre 8.2
Etat de l'art concernant les grandes ressources naturelles de la région Aquitaine.
(pp. 249-264, 22/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR REBX, IRSTEA, UPMC
Flux dynamics of planktic foraminiferal tests in the south-eastern Bay of Biscay (northeast Atlantic margin)
The temporal and water depth related dynamics of planktic foraminiferal fluxes in the south-eastern Bay of Biscay are discussed for a two year sampling period (June 2006-June 2008). Two sediment traps deployed at 800 m and 1700 m water depth at a mooring in 2000 m of water depth, were analyzed for the flux of planktic foraminiferal species > 150 μm, in comparison with the total mass flux. Total flux of planktic foraminifera shows seasonal maxima in spring/early summer (> 2000 Ind. m− 2 d− 1) and minima from late summer through winter (< 10 Ind. m− 2 d− 1). The flux of planktic foraminiferal tests in the intermediate to deep water column at the inner Bay of Biscay comprises an intermittent and regionally variable signal of seasonal surface water primary productivity. Significant lateral transport and flux of particles superimposed on the downward mass flux indicate a decoupling of fluxes between the 800-m and 1700-m traps. The 210Pb budget and the presence of certain benthic foraminiferal species in the midwater column prove that the lateral flux originated from the upper continental slope. Despite the temporal and vertical variations of the particulate flux, a well-defined seasonal flux signal can be deduced from the frequency of planktic foraminiferal species.
(Journal of Marine Systems. vol. 109-110, n° 0924-7963, pp. S169-S181, 22/04/2026)
BIAF, UA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LPO, IRD, IFREMER, UBO EPE, CNRS
Globex: wave dynamics on a gently sloping laboratory beach
As waves approach the shore, non-linearity in their dynamics becomes increasingly important. Most of our understanding of wave non-linearity has resulted from theoretical work, laboratory experiments and field studies on beaches slopes steeper than about 1:40. Here, very strong non-linear processes happen locally and on a short time scale, as demonstrated by narrow surf zones with plunging or collapsing breakers. The non-linearity on lower sloping beaches, typical of high-energy dissipative environments, has a different character, as it can now build up over a long period of time in a cross-shore extensive area. This second case of strong non-linearity is not well understood. This contribution serves to introduce the GLOBEX project, during which a high-resolution (in space and time) data set of the cross-shore evolution of short and infragravity waves was collected on a low-sloping (1:80) non-mobile laboratory beach for a range of wave conditions. Various other presentations at the conference will build on this introductory contribution.
(pp. 1351 - 1362, 22/04/2026)
IMAU, LEGI, UJF, Grenoble INP, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, M2C, UNICAEN, NU, INSU - CNRS, UNIROUEN, NU, CNRS, UC / UniCan, CESAM
Transient swash motions on a gently-sloping beach
Spectral and wavelet analyses are used to investigate run-up motion on a gently sloping beach with special attention devoted to the coupling between the long-period swash oscillations and the wave grouping outside the surf zone. Runup elevations were measured under random-wave conditions during the laboratory GLOBEX experiments carried out along a 1:80 sloping, fixed beach. A capacitance wire was deployed parallel to the bottom in order to detect the swash edge. The low Iribarren numbers involved in the experiments led to swash motions dominated by surf beat. High correlation levels between the scale-averaged wavelet power and the run-up suggest that low-frequency swash motions are still associated with the modulation of offshore swell waves. In addition, wavelet analysis supports the idea that swash-swash interactions are important in controlling swash oscillations.
(pp. 1385 - 1396, 22/04/2026)
UC / UniCan, LEGI, UJF, Grenoble INP, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Numerical modelling of equilibrium and evolving lightweight sediment laboratory beach profiles
The recent advances of numerical beach profile models allowed the simulation of on/offshore sandbar migrations on timescales of weeks to months with fair success. These models were systematically applied to natural, persistently evolving, beaches. In this contribution, we apply our model to small-scale laboratory experiments for which coarse and lightweight sediment is used to satisfy the laws of similitude in the flume. Such experiments can result in equilibrium beach profiles and provide detailed information on the respective role of undertow and wave nonlinearities on sediment transport and the resulting cross-shore sandbar migration. Here we first apply the coupled, wave-averaged, cross-shore waves-currents-bathymetric evolution model 1DBeach to an equilibrium beach profile. The model simulates an equilibrium beach profile with reasonable success. Yet, when applying the best fit parameters to a subsequent rapid onshore sandbar migration, the model fails in reproducing the overall beach profile evolution. Further model calibration on the evolving beach profile sequence shows that the model can actually reproduce the rapid onshore sandbar migration with a significant contribution of acceleration skewness. This suggests that a number of misspecifications of the physics remain in coupled, wave-averaged, cross-shore waves-currents-bathymetric evolution model. In addition, given that best-fit model free parameters are of the same order of magnitude of those found on natural beaches, our study suggests that small-scale experiments with coarse and lightweight sediment can be used to further explore the respective contribution of wave nonlinearities and undertow to sediment transport and the overall beach profile evolution.
(pp. 521 - 530, 22/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEGI, UJF, Grenoble INP, CNRS, DYNECO, IFREMER, IMAU
Contamination et physiologie des poissons exposés à des polluants
(22/04/2026)
LPGP, INRA, Biosit : Biologie - Santé - Innovation Technologique, IFREMER, UB, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UB, ULR, LIENSs, INSU - CNRS, ULR, CNRS, ULH, NU, BGMCD, IP, CNRS, PAnTher, ONIRIS, INRAE
Changes in the distribution of copepods in the Gironde estuary: A warming and marinisation consequence?
The Gironde is the largest estuary of South-West Europe and is one of the best monitored estuarine systems in the world. This macrotidal estuary is characterized by a low biodiversity in both oligo- and mesohaline zones. Its zooplankton community is constituted by only five major species, three calanoid copepods (including one invasive species) and two mysids. Retrospective analyses have already documented a warming associated to a phenomenon of marinisation. Here, we investigate the influence of both marinisation and warming on the spatial distribution and the abundance of copepods (i.e. Eurytemora affinis, Acartia bifilosa and neritic species) in the Gironde estuary. We modelled the environmental envelope of the copepods as a function of salinity and temperature to demonstrate that the alteration of their longitudinal distribution in the estuary between 1975 and 2003 was the result of both changing temperature and salinity. Although the upstream movement of neritic species was mostly related to salinity, we show that the augmentation of both temperature and salinity was at the origin of the upstream progression of both A. bifilosa and E. affinis. These results suggest that the distribution of copepods can be affected by both anthropogenic forcing and climatic change, which modulate the physic-chemistry of the Gironde estuary.
(Estuarine, Coastal and Shelf Science. vol. 134, n° 0272-7714, pp. 150-161, 22/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR EPBX, IRSTEA, LOG, INSU - CNRS, ULCO, CNRS, IRD [Ile-de-France]