Extreme storms during the last 6500 years from lagoonal sedimentary archives in the Mar Menor (SE Spain)
Storms and tsunamis, which may seriously endanger human society, are amongst the most devastating marine catastrophes that can occur in coastal areas. Many such events are known and have been reported for the Mediterranean, a region where high-frequency occurrences of these extreme events coincides with some of the most densely populated coastal areas in the world. In a sediment core from the Mar Menor (SE Spain), we discovered eight coarse-grained layers which document marine incursions during periods of intense storm activity or tsunami events. Based on radiocarbon dating, these extreme events occurred around 5250, 4000, 3600, 3010, 2300, 1350, 650, and 80 years cal BP. No comparable events have been observed during the 20th and 21st centuries. The results indicate little likelihood of a tsunami origin for these coarse-grained layers, although historical tsunami events are recorded in this region. These periods of surge events seem to coincide with the coldest periods in Europe during the late Holocene, suggesting a control by a climatic mechanism for periods of increased storm activity. Spectral analyses performed on the sand percentage revealed four major periodicities of 1228 ± 327, 732 ± 80, 562 ± 58, and 319 ± 16 years. Amongst the well-known proxies that have revealed a millennial-scale climate variability during the Holocene, the ice-rafted debris (IRD) indices in the North Atlantic developed by Bond et al. (1997, 2001) present a cyclicity of 1470 ± 500 years, which matches the 1228 ± 327-year periodicity evidenced in the Mar Menor, considering the respective uncertainties in the periodicities. Thus, an in-phase storm activity in the western Mediterranean is found with the coldest periods in Europe and with the North Atlantic thermohaline circulation. However, further investigations, such as additional coring and high-resolution coastal imagery, are needed to better constrain the main cause of these multiple events.
(Climate of the Past. vol. 12, n° 1814-9324, pp. 1389-1400, 25/10/2026)
INSU - CNRS, UM, CNRS, UA, ASM, UPVM, CNRS, MC, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, GEOTRAC, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, GLACCIOS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA
Climate change and ecosystems dynamics over the last 6000 years in the Middle Atlas, Morocco
The present study aims at reconstructing past climate changes and their environmental impacts on plant ecosystems during the last 6000 years in the Middle Atlas, Morocco. Mean January temperature (Tjan), annual precipitation (Pann), winter (Pw) and summer (Ps) precipitation, and a seasonal index (SI) have all been quantified from a fossil pollen record. Several bio- and geo-chemical elements have also been analysed to evaluate the links between past climate, landscape, and ecosystem changes. Over the last 6000 years, climate has changed within a low temperature and precipitation range with a trend of aridity and warming towards the present. Tjan has varied within a ca. 2 °C range, and Pann within less than 100 mm yr-1. The long-term changes reconstructed in our record between 6 ka cal BP and today are consistent with the aridity trend observed in the Mediterranean basin. Despite the overall limited range of climate fluctuation, we observe major changes in the ecosystem composition, the carbon isotopic contents of organic matter (δ13C), the total organic carbon and nitrogen amount, and the carbon to nitrogen ratio (C / N) after ca. 3750 cal BP. The main ecosystem changes correspond to a noticeable transition in the conifer forest between the Atlas cedar, which expanded after 3750 cal BP, and the pine forest. These vegetation changes impacted the sedimentation type and its composition in the lake. Between 5500 and 5000 cal BP, we observe an abrupt change in all proxies which is coherent with a decrease in Tjan without a significant change in the overall amount of precipitation.
(Climate of the Past. vol. 12, n° 1814-9324, pp. 1029-1042, 25/10/2026)
URAC 45, UCD, LGR, UCA, UMR ISEM, Cirad, IRD, EPHE, PSL, UM, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
To boldly climb: behavioural and cognitive differences in migrating European glass eels
European eel (Anguilla anguilla) is a catadromous fish species that received substantial attention as its population has markedly declined in the last three decades. The possible causes of this decline include habitat fragmentation factors such as dams and weirs. In some cases, these obstacles are equipped with fish friendly passage devices that may select young eels according to their climbing behaviour. We tested how individual climbing tendency was related to the event of fishway passage experienced in the field and classified fish climbing profiles as climbing ‘leaders', ‘followers', ‘finishers' and ‘no climbers'. Moreover, we analysed the brain transcription level of genes related to neurogenesis and synaptic plasticity and compared it to climbing profiles.We found that fish from the upstream segments of an impounded river had a higher climbing propensity. Their behaviour was also more repeatable throughout the whole test than the obstacle-naive fish from the downstream segment. Moreover, we found that boldly climbing ‘leaders' had lower levels of transcription of synapse-related genes than the climbing ‘followers'. These differences could be related to coping styles of fish, where proactive ‘leaders' express a routine and risky behaviour, whereas reactive fish need an environmental assessment before exploratory behaviour. Our study showed that differences in climbing propensity exist in glass eels separated by water obstacles. Moreover, eels could adopt climbing different strategies according to the way they deal with environmental stress and to the cognitive abilities they possess.
(Royal Society Open Science. vol. 3, n° 2054-5703, pp. 150665, 25/10/2026)
UR EABX, IRSTEA, SETE, UT3, Comue de Toulouse, CNRS, EDF R&D STEP, EDF R&D, EDF [E.D.F.], EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Dynamics of particulate organic matter in a coastal system characterized by the occurrence of marine mucilage – A stable isotope study
In coastal systems, particulate organic matter (POM) originates from various autochthonous and allochthonous organic matter sources. Also, some coastal systems are characterized by the occurrence of large amounts of mucilaginous material of biologic origin (i.e. phytoplankton, bacteria), which aggregates and potentially traps other organisms and particles present in the water column. This study focuses on POM origin and spatio-temporal dynamics in the South-East coast of the Bay of Biscay, an area subject to mucilage occurrence. In order to investigate POM quantitative and qualitative (C and N elemental and isotopic ratios) characteristics, sampling was performed over an annual cycle at two sites experiencing different mucilage occurrence and river influence. Contribution of phytoplankton, terrestrial POM and anthropogenic POM to coastal-POM composition was calculated using a three-sources mixing model. Overall, phytoplankton dominated the coastal-POM composition at all seasons, sites and most of the depths (71.6 ± 24.2%). Terrestrial-POM contribution was moderate (22.7 ± 21.8%) and anthropogenic-POM contribution was usually negligible (5.7 ± 7.4%). Both sites mainly exhibited similar vertical and temporal variations in terms of POM origin and dynamics: terrestrial-POM contribution increased with depth and was higher in winter at all depths and in autumn in bottom waters, compared to other seasons. The main differences between both sites were related to the vertical dynamics of the terrestrial contribution to the coastal POM. Horizontal, vertical and temporal variation of POM composition was linked to processes driving the sedimentary hydrodynamics: the river flow, the direction of the river plume and events of sediment resuspension/deposition. During the study period, the mucilage occurred only as flocs (small aggregates). The mucilage was of autochthonous origin and did not trap detectable amount of allochthonous material. © 2016 Elsevier B.V.
(Journal of Sea Research (JSR). vol. 116, n° 1385-1101, pp. 12--22, 25/10/2026)
LPCNO, INSA Toulouse, INSA, Comue de Toulouse, ICT, IRD, UT3, Comue de Toulouse, INC-CNRS, CNRS, Toulouse INP, Comue de Toulouse, IRSAMC, UT3, Comue de Toulouse, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IPREM, UPPA, INC-CNRS, CNRS, VUB
Carbon emission along a eutrophication gradient in temperate riverine wetlands: effect of primary productivity and plant community composition
1. Eutrophication increases primary productivity and favours the predominance of floating vegetation in wetlands. Carbon (C) fluxes in wetlands are strongly driven by primary productivity and can differ by vegetation type. However, to the best of our knowledge, the role of eutrophication in C fluxes has rarely been assessed. 2. Consequently, we aimed to measure the seasonal variation in carbon dioxide (CO2) and methane (CH4) fluxes at six aquatic sites in four temperate wetlands, ranging along a gradient of sediment total phosphorus content, and determine whether C fluxes correlate with above-ground net primary productivity (ANPP) and plant community composition along this eutrophication gradient. 3. Daytime CO2 emissions were significantly and negatively correlated with wetland net primary productivity as a result of the greater C fixation by photosynthesis during the peak of production. Conversely, CH4 emissions were significantly and positively correlated with wetland ANPP, possibly due to higher litter production and anaerobic decomposition. 4. The highest CH4 emissions were observed above floating vegetation, which favoured hypoxic conditions in the water column. CH4 emissions including ebullition were higher above macroalgal belts than above vascular plants with floating leaves. CH4 emissions without ebullition (i.e. resulting from plant transport and diffusion) better correlated with the abundance of macroalgae than with the abundance of vascular plants with floating leaves. 5. Our results suggest that eutrophication may greatly modify CO2 and CH4 emissions from wetlands through changes in vegetation type and productivity.
(Freshwater Biology. vol. 61, n° 0046-5070, pp. 1405–1420, 25/10/2026)
LEHNA, UCBL, ENTPE, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LCE, CNRS, UMLP
Molecular and phenotypic responses of Japanese medaka (Oryzias latipes) early life stages to environmental concentrations of cadmium in sediment
Japanese medaka embryos were exposed to environmental concentrations of cadmium (Cd) to investigate adverse and adaptive responses in fish early life stages. Embryos were exposed during their whole development by static sediment-contact to environmental Cd concentrations (2 and 20 μg/g dry weight). Cd bioaccumulation, developmental defects, biochemical and biomolecular (qRT-PCR) responses were analyzed in embryos and hatchlings. A dose-dependent increase of Cd bioaccumulation and developmental defects was observed at hatching. Cd had clear impacts on heartbeat and cardiac morphogenesis and also induced to spinal deformities. The profile and the level of gene transcription were differentially modulated according to the Cd concentration, the duration of exposure and/or the developmental stage of fish. Pro-apoptotic bax and DNA repair rad51 transcripts were significantly repressed in embryos exposed to the highest Cd concentration. Repression of these genes was correlated to the increase of heart rate in 6-day-old embryos. NADH-dehydrogenase nd5 gene transcription was inhibited in larvae at the lowest concentration suggesting mitochondrial respiratory chain impairment, in association with Cd-induced teratogenicity. Finally, wnt1 gene was overexpressed indicating putative deregulation of Wnt signaling pathway, and suggested to be implied in the occurrence of some spinal and cardiac deformities. Results of this study permitted to propose some promising markers at the transcriptional and phenotypical level, responding to environmental concentrations of Cd. The present work also highlights the usefulness of the modified version of the medaka embryo-larval assay with sediment-contact exposure (MELAc) to investigate the toxicity and the modes of action of sediment-bound pollutants.
(Environmental Science and Pollution Research. vol. 23, n° 0944-1344, pp. 17969-17981, 25/10/2026)
SEBIO, INERIS, URCA, ULH, NU, URCA, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Environmental responses of the Northeast Antarctic Peninsula to the Holocene climate variability
In this study, we present a unique high-resolution Holocene record of oceanographic and climatic change based on analyses of diatom assemblages combined with biomarker data from a sediment core collected from the Vega Drift, eastern Antarctic Peninsula (EAP). These data add to the climate framework already established by high-resolution marine sedimentary records from the Palmer Deep, western Antarctic Peninsula (WAP). Heavy sea ice conditions and reduced primary productivity were observed prior to 7.4 ka B.P. in relation with the proximity of the glacial ice melt and calving. Subsequent Holocene oceanographic conditions were controlled by the interactions between the Westerlies-Antarctic Circumpolar Current (ACC)-Weddell Gyre dynamics. A warm period characterized by short seasonal sea ice duration associated with a southern shift of both ACC and Westerlies field persisted until 5 ka B.P. This warm episode was then followed by climate deterioration during the middle-to-late Holocene (5 to 1.9 ka B.P.) with a gradual increase in annual sea ice duration triggered by the expansion of the Weddell Gyre and a strong oceanic connection from the EAP to the WAP. Increase of benthic diatom species during this period was indicative of more summer/autumn storms, which was consistent with changes in synoptic atmospheric circulation and the establishment of low- to high-latitude teleconnections. Finally, the multicentennial scale variability of the Weddell Gyre intensity and storm frequency during the late Holocene appeared to be associated with the increased El Niño–Southern Oscillation frequency.
(Paleoceanography. vol. 31, n° 0883-8305, pp. 131–147, 25/10/2026)
UNAM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LOCEAN, IPSL, ENS-PSL, PSL, UVSQ, UPMC, CEA, INSU - CNRS, X, IP Paris, CNES, CNRS, MNHN, IRD, UPMC, INSU - CNRS, CNRS, USF, ULaval, INSU - CNRS, CNRS
Transfert de composés per- et poly-fluorés du sédiment au poisson
Dans le contexte du Plan d’actions sur les polychlorobiphényles, des composés per- et polyfluorés ont fait l’objet d’analyses dans la chair des poissons, montrant un accroissement notable des concentrations de plusieurs PFAS à l’aval de Lyon. Les PFAS, composés très persistants, ont un comportement différent des micropolluants hydrophobes « classiques », justifiant de chercher à mieux comprendre leur devenir et leurs voies de transfert dans les réseaux trophiques, le rôle du sédiment dans ce devenir, et les facteurs contrôlant l’accumulation par les organismes. La présente étude visait à mieux comprendre le devenir des PFAS dans le Rhône, et plus précisément de documenter les cinétiques d’accumulation de quelques composés perfluorés pour deux espèces d’invertébrés benthiques (larves de chironome, Chironomus riparius, et gammares, Gammarus spp.), d’évaluer le rôle du sédiment dans le processus d’accumulation, et de reconstituer l’historique de la contamination sur un site à l’aval de Lyon (lône de l’Ile du Beurre) à l’aide d’une carotte de sédiment. Un profil temporel et spatial de la contamination des sédiments a été établi, la contamination de trois espèces de poissons (barbeau fluviatile, Barbus barbus, gardon, Rutilus rutilus, et goujon, Gobio gobio) et de leurs proies par une gamme d’une vingtaine de PFAS a été déterminée, et des essais d’accumulation de ces PFAS au laboratoire à partir du sédiment de l’Ile du Beurre ont été réalisés avec des larves de chironomes et des gammares. Le gardon est généralement moins contaminé que les deux autres espèces, sauf pour l’acide perfluorooctane sulfonique (PFOS). Le barbeau est en général plus contaminé que le goujon, sauf pour le PFOS, le perfluorooctanoate (PFOA), le perfluorodécane sulfonate (PFDS) et l’acide 6:2 fluorotélomère sulfonique (6:2FTSA). L’influence de la taille (proxy de l’âge) sur l’accumulation des composés dominants dans les sédiments de l’Ile du Beurre (acides perfluoroundécanoïque - PFUnDA et perfluorotridécanoïque PFTrDA) n’a pas été mise en évidence. En revanche, pour le PFOS et le PFNA (acide perfluorononanoïque), les barbeaux juvéniles sont plus contaminés que les individus plus gros et plus âgés, ce qui suggère une moindre capacité à les éliminer chez les juvéniles. Le contenu stomacal des barbeaux comprend une forte proportion de gammares, celui des goujons est dominé par les chironomes, ce qui contribue à expliquer les différences de contamination entre espèces. Deux types d’indicateur de bioamplification ont été testés, facteur de bioamplification (BMF) ajusté au niveau trophique pour des couples prédateur-proie constitués de barbeaugammares et goujon-chironomes, et des facteurs d’amplification trophique (TMF), déterminés pour le réseau trophique du barbeau. PFUnDA, PFDoDA (acide perfluorododécanoïque), le PFTrDA, PFOS et FOSA (perfluorooctane sulfonamide) sont clairement bioamplifiés chez le barbeau. Chez le goujon, les mêmes composés, plus PFOA, PFNA, PFHxS (acide perfluorohexane sulfonique) et PFDS sont également bioamplifiés. Les BMF tendent à augmenter quand le nombre de carbones perfluorés des composés augmente. Lors de tests en laboratoire, l’accumulation et l’élimination des PFAS du sédiment de l’Ile du Beurre sont rapides chez le chironome, et plus lentes chez le gammare où l’état stable n’était pas atteint en 21 jours. L’hypothèse d’une dépendance à la concentration, ou transport actif de ces composés lors de l’accumulation, a également été examinée chez le chironome à l’aide d’un test sur sédiment enrichi. Si ce mécanisme ne peut être exclu pour le PFTrDA, il n’explique pas mieux l’accumulation que la diffusion simple. L’accumulation, chez le chironome et le gammare, est plus importante pour les composés à longue chaîne perfluorée (C8), notamment en raison de cinétiques d’élimination plus lentes, notamment chez le gammare.
(pp. 75, 25/10/2026)
UR MALY, IRSTEA, UT, NEOLAiA, EAWAG, EPFL, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UNILIM
Estuarine habitats structure zooplankton communities: Implications for the pelagic trophic pathways
Estuarine ecosystems have been described as a mosaic of habitats exhibiting different physical, biological and chemical properties and processes. These habitats are of primary importance for fishes, providing refuges and/or food for juveniles. While it is well known that habitats contribute also to the structuration of meio- and macrobenthic assemblages, this concept of habitat has never been associated to zooplankton communities, a major food resource for many pelagic fishes during summer in North-European estuaries. The objective of this work was thus to assess if estuarine habitats, in addition to the salinity gradient, structured zooplankton communities as well. Sampling was conducted at high tide during summer in a highly turbid system, the Gironde estuary, for which primary production and thus food resource at the basis of the food web is strongly limited. The results showed that even if the upstream-downstream estuarine gradient was the main factor structuring zooplankton at the scale of the estuary, there was a significant difference of zooplankton assemblages between samples collected over subtidal areas and those collected over intertidal areas. More particularly, the estuarine gradient was associated to the distribution pattern of species while difference between subtidal and intertidal samples were mainly due to difference in the level of abundance of species. Stable isotope analysis revealed that these zooplanktonic omnivorous species may be attracted to intertidal mudflats by microphytobenthos availability and that some planktivorous fishes, in particular Alosa fallax, preferentially fed on this zone. The role of intertidal habitats in structuring zooplankton assemblages suggests that this habitat strongly participates to the production of planktivorous species and that it represents a biotic vector of carbon resources toward subtidal areas. The loss of tidal flats habitats could thus have consequences on the functioning of pelagic system as well.
(Estuarine, Coastal and Shelf Science. vol. 179, n° 0272-7714, pp. 99-111, 25/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR EABX, IRSTEA
The Sahelian agro-ecosystem vulnerability to an acceleration of ice-sheet melting during the 21st century
During the 20th century, Sahelian drought episodes like those between 1972 and 1982 showed the vulnerability of the Sahelian agro-ecosystem provoking significant intraregional southward human migrations, to or near the coast. According to the latest IPCC report, the Sahel could become increasingly impacted by climate change during the 21st century because of a lagged and shorter rainfall season having the potential to induce a drastic destabilization of the Sahelian agro-ecosystem and to heavily impact the population. Such effects could be further amplified by a net increase of the Sahelian population. Drastic climate changes over tropical areas also occurred in the past: weakening of the West African Monsoon and megadrought Sahelian episodes have been reported with a close correspondence between the large rainfall decrease and the massive freshwater discharges following ice-sheet melting or iceberg surges. During the last decades a continuous acceleration of ice-sheet mass loss has been observed and post IPCC-AR5 studies suggest the ice-sheet contribution to future sea-level rise could be revised upward due partly to the lack of an accurate representation of ice-ocean interactions. The release of freshwater discharge in response to ice-sheet instability could have large consequences on the most vulnerable regions, such as the tropical areas. To investigate the impacts of large ice-sheet instability during the 21st century, we first explore the climatic signature of Greenland or Antarctic ice-sheet collapse scenarios corresponding to 0.5 to 1.5 meter of sea-level rise, superimposed to the RCP8.5 scenario. We show that a freshwater discharge coming from Greenland melting induces a significant decrease of summer monsoon rainfall, that may lead to changes in agricultural practices. Combined with increasing demography, this has the potential to induce important human migration flows. Without adaptation measures, we estimate that tens to hundreds million people could be forced to leave the Sahel by the end of the 21st century, not accounting for the direct migratory impact of sea-level rise over coastal areas.
(. vol. 18, pp. 7977, 25/10/2026)
LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, PARVATI, LOCEAN, IPSL, ENS-PSL, UVSQ, UPMC, CEA, INSU - CNRS, X, CNES, CNRS, MNHN, IRD, UPMC, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CEARC, UVSQ, UCM