Sea ice seasonality during the Holocene, Adélie Land, East Antarctica
Thin sections of laminated cores from different Antarctic coastal areas have demonstrated the potential of diatom species to document climate change at the seasonal scale. Here we present the relative abundances of four diatom species and species groups (Fragilariopsis curta group as a proxy for yearly sea ice cover, F. kerguelensis as a proxy for summer sea-surface temperature, Chaetoceros Hyalochaete resting spores as a proxy for spring sea ice melting and the Thalassiosira antarctica group as a proxy for autumn sea ice formation) in core MD03-2601 retrieved off Adélie Land on the Antarctic continental shelf. These abundances were compared to surface temperatures and sea ice cover modelled over the last 9000 years. Both the marine records and the simulated climate demonstrated a cooler Early Holocene (9000-7700 years BP), a warmer Mid-Holocene (7700-4000 years BP) and a colder Late Holocene (4000-1000 years BP). Yearly sea ice cover followed an inverse pattern to temperatures with less sea ice during the Mid-Holocene Hypsithermal than during the Late Holocene Neoglacial. However, diatom census counts and model output indicate that sea ice spring melting happened earlier in the season, as expected, but that autumn sea ice formation also occurred earlier in the season during the Hypsithermal than during the colder Neoglacial, thereby following seasonal changes in local insolation.
(Marine Micropaleontology. vol. 66, n° 0377-8398, pp. 222-232, 26/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Cadmium uptake by the European eel: Trophic transfer in field and experimental investigations
Due to its status of threatened species and being heavily contaminated by metals, the European eel (Anguilla anguilla) was selected to investigate cadmium contamination levels of fish settled along a historically cadmium-contaminated hydrosystem, the GaronneGironde continuum (France), according to its various location sites and fish length. Results have shown an important site effect on cadmium concentrations in liver but not in gills, highlighting the possible predominance of the trophic exposure route. Subsequently, uncontaminated eels were experimentally exposed to cadmium by water uptake and/or trophic route(s). Eels were fed with different preys: white shrimps collected in an unpolluted area in the Gironde estuary, and cadmium-enriched shrimps. Data obtained tend to show that the use of cadmium-enriched food during experimental investigations triggers an underestimation of the metal trophic transfer rate. These two complementary approaches provide some elements to suggest that the trophic route plays an important role in cadmium contamination of wild eels.
(Ecotoxicology and Environmental Safety. vol. 70, n° 0147-6513, pp. 10-19, 26/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR EPBX, CEMAGREF
Nitrous oxide emissions from tropical hydroelectric reservoirs
We report original data on nitrous oxide (N2O) fluxes from two tropical reservoirs, their rivers below the dam, and from natural aquatic ecosystems and rainforest soils in French Guiana and Panama. We also review published N2O fluxes from other tropical reservoirs and natural environments. We show that: (1) N2O emissions from tropical reservoirs occur mainly at the reservoir surface, fluxes downstream of dams being minor; (2) Because pre-flooding natural N2O fluxes are significant, the net N2O emissions from reservoirs are less than ∼50-70% of gross N2O emissions; (3) the contribution of N2O to the global warming potential of emissions from reservoirs could be significant for gross emissions, but less than 10% for net emissions, disregarding N2O degassing emissions.
(Geophysical Research Letters. vol. 35, n° 0094-8276, pp. L06404, 26/10/2026)
LAERO, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LACy, INSU - CNRS, UR, CNRS
Identification of a minimal adequate model to describe the biomass dynamics of river epilithon
(River Research and Applications. vol. 24, n° 1535-1459, pp. 36-53, 26/10/2026)
LEFE, INEE-CNRS, CNRS, UT3, Comue de Toulouse, CNRS, Toulouse INP, Comue de Toulouse, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
The Fetch Campaign, study of the turbulent fluxes, surface waves and remotely sensed parameters in fetch limited situations
description of the Fetch Campaign conducted in the Golfe du Lion in Mediterranéean sea
(26/10/2026)
CETP, UVSQ, INSU - CNRS, CNRS, SA, UVSQ, UPMC, INSU - CNRS, CNRS, IRPHE, AMU, ECM, CNRS, LEPI, UTLN, APL/RSMAS, RSMAS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LAERO, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNRS, FIMR, DIROP/MAR, DIROP, IFREMER
Application de la théorie SLOSS (Single Large or Several Small) aux communautés périphytiques de deux cours d'eau : à superficie égale, est-il préférable d'échantillonner une grande réserve ou plusieurs petites?
La théorie de la biogéographie insulaire repose sur le fait que la richesse spécifique des peuplements fragmentés dépend de l'équilibre entre taux d'immigration et taux d'extinction, la taille des « réserves naturelles » de l'habitat étant susceptible de conditionner l'efficacité de la conservation de la biodiversité (Diamond, 1975). La distribution spatiale des communautés pose dans la pratique le problème de bien déterminer la taille des réserves à étudier afin d'éviter le sous-échantillonnage. Dans cette étude des communautés périphytiques (diatomées et bactéries) de la Vézère et de la Garonne, nous avons cherché à identifier les apports du choix, à superficie identique échantillonnée, d'un prélèvement sur substrat de grande taille (Single Large) vs. plusieurs petits (Several Small). Des analyses quantitatives globales révèlent que les tendances sont variables selon le cours d'eau et selon les paramètres étudiés (matière sèche, chlorophylle, densité de diatomées). En règle générale, la quantité de biomasse par unité de surface est plus importante pour les grands substrats échantillonnés, soutenant la théorie selon laquelle une grande réserve est plus efficace que deux plus petites de superficie égale. L'étude qualitative souligne également l'influence de la taille de la réserve échantillonnée, en termes de diversité mais également en termes de structure spécifique, la composition des prélèvements réalisés sur substrats de plus grande taille indiquant une complexification plus rapide de la communauté.
(pp. 1, 26/10/2026)
UR REBX, CEMAGREF, LEFE, INEE-CNRS, CNRS, UT3, Comue de Toulouse, CNRS, Toulouse INP, Comue de Toulouse, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Live (stained) benthic foraminifera from the Rhone prodelta: environmental controls and temporal variability
(26/10/2026)
BIAF, UA, LPGN, UN, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, OCEANIS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, CEFREM, UPVD, INSU - CNRS, CNRS, CEFREM, UPVD, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Organic matter dynamics and budgets in the turbidity maximum zone of the Seine Estuary (France)
Organic matter was studied in the turbidity maximum zone (TMZ) of the Seine Estuary during 8 tidal cycles from April to October in 2001, 2002 and 2003, covering a salinity range from 0 to 27. The hydrological conditions were quite varied (extremely wet in 2001, unusually dry in 2003). A particularly striking feature is the high organic matter content in the suspended solids (SS) of the Seine estuary (4-5%). By determining micro-organism activity and organic carbon partitioning, either linked to particles or in dissolved forms, and estimating the TMZ water volumes, together with SS, we extrapolated these activities and stocks to the whole TMZ. Carbon metabolism in the TMZ and fluxes upstream of the TMZ were compared on the dates of field surveys, and the routes and fate of carbon in the TMZ were quantified in order to learn about the trophic status of this estuarine zone in terms of autotrophy vs. heterotrophy. The upstream total organic carbon (TOC) fluxes (48% of particulate organic carbon (POC), 52% of dissolved organic carbon (DOC) on average) varied fourfold between the surveys, reaching the highest value of 280 TC d-1 during the wet summer of 2001; and the lowest value of about 70 TC d-1 in August 2003. Whereas nearly all of the DOC flux entering the TMZ reaches the coastal marine zone, mostly (at least 85%) in a refractory form, the POC accumulates in the TMZ of the estuarine channel, particle exportation being negligible. In the TMZ, biodegradation of DOC was, on average, much less (only a 2% decrease in the BDOC/DOC ratio between the TMZ upstream and downstream fluxes) than biodegradation of POC (11%). A simplified model of the TMZ (LIFT- Lumped Idealisation of the ecological Functioning in estuarine Turbidity maximum) was constructed for investigating the dynamics of organic matter on a seasonal scale. The agreement between observation and calculation allowed us to run sensitivity tests using new constraints; reductions of the upstream fluxes of phytoplankton and organic carbon showed that the high content of organic matter, originating mostly from the domestic effluents of the Paris conurbation, can explain the high organic content of the Seine estuary TMZ.
(Estuarine, Coastal and Shelf Science. vol. 77, n° 0272-7714, pp. 150-162, 26/10/2026)
LPMA, UPMC, UPD7, CNRS, UPMC, SISYPHE, UPMC, EPHE, PSL, PSL, CNRS, GEOSCIENCES, PSL, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ULB
Contribution du cadmium au déclin des populations d'anguille européenne (Anguilla anguilla) : impact sur la réussite de la migration de reproduction
Les populations d'anguille européenne (Anguilla anguilla L.) déclinent sévèrement depuis quelques décennies, menaçant cette espèce d'extinction. Dans ce contexte, nous avons étudié l'effet potentiel du cadmium (Cd), un métal non essentiel largement répandu dans l'environnement, sur les capacités de reproduction de l'anguille européenne.
(pp. 1, 26/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, MNHN, UR EPBX, CEMAGREF
How cadmium could compromise the completion of the european eel's reproductive migration
The European eel (Anguilla anguilla L.) is severely threatened with extinction. Surprisingly, even though their unusual life cyclemakesthem particularly vulnerable to pollution, the possible contribution of contamination remains especially poorly known. Here we have investigated the possible effect of cadmium (Cd), a widespread nonessential metal, on eel reproductive capacities. Both control and Cd precontaminated female silver eels were experimentally matured and forced to swim in metal-free conditions to mimic their reproductive migration. Cd pre-exposure was found to strongly stimulate the pituitary-gonad-liver axis of maturing female silver eels leading to early and enhanced vitellogenesis. This was followed by a strong phenomenon of oocyte atresia and eel mortality. These phenomena occurred before oocytes could reach full maturation and were associated with a large entry of both vitellogenin and Cd into the ovaries. Indeed, a redistribution of previously stored cadmium, even from the low Cd levels of control eels, was observed during sexual maturation. Atresia and mortality phenomena were also associated with an overexpression of the pituitary gene encoding the growth hormone, a marker of physiological stress and energy reserves exhaustion. Significantly, these devastating effects of Cd were observed in organisms that presented liver and kidney Cd concentrations still below those observed in eels from Cd contaminated hydrosystems. Our research shows how common levels of cadmium contamination could disrupt endocrine pathways implicated in gonad maturation and subsequently impair reproductive capacity of eel future genitors.
(Environmental Science and Technology. vol. 42, n° 0013-936X, pp. 4607-4612, 26/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CNRS, BOME, MNHN, UPMC, CNRS, UR EPBX, CEMAGREF