Paradoxical cold conditions during the medieval climate anomaly in the Western Arctic
In the Northern Hemisphere, most mountain glaciers experienced their largest extent in the last millennium during the Little Ice Age (1450 to 1850 CE, LIA), a period marked by colder hemispheric temperatures than the Medieval Climate Anomaly (950 to 1250 CE, MCA), a period which coincided with glacier retreat. Here, we present a new moraine chronology based on 36Cl surface exposure dating from Lyngmarksbræen glacier, West Greenland. Consistent with other glaciers in the western Arctic, Lyngmarksbræen glacier experienced several advances during the last millennium, the first one at the end of the MCA, in ~1200 CE, was of similar amplitude to two other advances during the LIA. In the absence of any significant changes in accumulation records from South Greenland ice cores, we attribute this expansion to multi-decadal summer cooling likely driven by volcanic and/or solar forcing, and associated regional sea-ice feedbacks. Such regional multi-decadal cold conditions at the end of the MCA are neither resolved in temperature reconstructions from other parts of the Northern Hemisphere, nor captured in last millennium climate simulations.
(Scientific Reports. vol. 6, n° 2045-2322, pp. 32984, 22/06/2026)
LGP, UP1, UPEC UP12, CNRS, OSUG, Grenoble INP, INSU - CNRS, IRSTEA, USMB [Université de Savoie] [Université de Chambéry], CNRS, UGA [2016-2019], LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, GLACCIOS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CEREGE, IRD, INRA, AMU, CdF (institution), INSU - CNRS, CNRS, MMU
Detecting the exposure to Cd and PCBs by means of a non-invasive transcriptomic approach in laboratory and wild contaminated European eels (Anguilla anguilla)
Detecting and separating specific effects of contaminants in a multi-stress field context remain a major challenge in ecotoxicology. In this context, the aim of this study was to assess the usefulness of a non-invasive transcriptomic method, by means of a complementary DNA (cDNA) microarray comprising 1000 candidate genes, on caudal fin clips. Fin gene transcription patterns of European eels (Anguilla anguilla) exposed in the laboratory to cadmium (Cd) or a polychloro-biphenyl (PCBs) mixture but also of wild eels from three sampling sites with differing contamination levels were compared to test whether fin clips may be used to detect and discriminate the exposure to these contaminants. Also, transcriptomic profiles from the liver and caudal fin of eels experimentally exposed to Cd were compared to assess the detection sensitivity of the fin transcriptomic response. A similar number of genes were differentially transcribed in the fin and liver in response to Cd exposure, highlighting the detection sensitivity of fin clips. Moreover, distinct fin transcription profiles were observed in response to Cd or PCB exposure. Finally, the transcription profiles of eels from the most contaminated site clustered with those from laboratory-exposed fish. This study thus highlights the applicability and usefulness of performing gene transcription assays on non-invasive tissue sampling in order to detect the in situ exposure to Cd and PCBs in fish.
(Environmental Science and Pollution Research. vol. 23, n° 0944-1344, pp. 5431--5441, 22/06/2026)
µVIS X-ray Imaging Centre, INRS, LPTC, UB, CNRS, ISM, UB, INC-CNRS, CNRS, UR EABX, IRSTEA, IBIS, ULaval, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Decadal prediction skill in the ocean with surface nudging in the IPSL-CM5A-LR climate model
Two decadal prediction ensembles, based on the same climate model (IPSL-CM5A-LR) and the same surface nudging initialization strategy are analyzed and compared with a focus on upper-ocean variables in different regions of the globe. One ensemble consists of 3-member hindcasts launched every year since 1961 while the other ensemble benefits from 9 members but with start dates only every 5 years. Analysis includes anomaly correlation coefficients and root mean square errors computed against several reanalysis and gridded observational fields, as well as against the nudged simulation used to produce the hindcasts initial conditions. The last skill measure gives an upper limit of the predictability horizon one can expect in the forecast system, while the comparison with different datasets highlights uncertainty when assessing the actual skill. Results provide a potential prediction skill (verification against the nudged simulation) beyond the linear trend of the order of 10 years ahead at the global scale, but essentially associated with non-linear radiative forcings, in particular from volcanoes. At regional scale, we obtain 1 year in the tropical band, 10 years at midlatitudes in the North Atlantic and North Pacific, and 5 years at tropical latitudes in the North Atlantic, for both sea surface temperature (SST) and upper-ocean heat content. Actual prediction skill (verified against observational or reanalysis data) is overall more limited and less robust. Even so, large actual skill is found in the extratropical North Atlantic for SST and in the tropical to subtropical North Pacific for upper-ocean heat content. Results are analyzed with respect to the specific dynamics of the model and the way it is influenced by the nudging. The interplay between initialization and internal modes of variability is also analyzed for sea surface salinity. The study illustrates the importance of two key ingredients both necessary for the success of future coordinated decadal prediction exercises, a high frequency of start dates is needed to achieve robust statistical significance, and a large ensemble size is required to increase the signal to noise ratio.
(Climate Dynamics. vol. 47, n° 0930-7575, pp. 1225-1246, 22/06/2026)
PARVATI, LOCEAN, IPSL, ENS-PSL, UVSQ, UPMC, CEA, INSU - CNRS, X, CNES, CNRS, MNHN, IRD, UPMC, INSU - CNRS, CNRS, OCCR, UNIBE, CEP, UNIBE, LOCEAN, IPSL, ENS-PSL, PSL, UVSQ, UPMC, CEA, INSU - CNRS, X, IP Paris, CNES, CNRS, MNHN, IRD, UPMC, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UOR, AOS Program, GFDL, NOAA
Organic and inorganic contamination impacts on metabolic capacities in American and European yellow eels
(Canadian Journal of Fisheries and Aquatic Sciences. vol. 73, n° 0706-652X, pp. 1557--1566, 22/06/2026)
ISM, UB, INC-CNRS, CNRS, LPTC, UB, CNRS, µVIS X-ray Imaging Centre, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, INRS
Spatial and temporal patterns of occurrence of three alien hydromedusae, Blackfordia virginica (Mayer, 1910), Nemopsis bachei (Agassiz, 1849) and Maeotias marginata (Modeer, 1791), in the Gironde Estuary (France)
The species composition and seasonal abundance patterns of gelatinous zooplankton are poorly known for many European coastal-zone waters. The seasonal abundance and distribution of the dominant species of hydromedusae along a salinity gradient within the Gironde Estuary, Atlantic coast of France, were evaluated based on monthly surveys, June 2013 to April 2014. The results confirmed the presence of three species considered to be introduced in many coastal ecosystems around the world: Nemopsis bachei (Agassiz, 1849), Blackfordia virginica (Mayer, 1910), and Maeotias marginata (Modeer, 1791). These species were found at salinities ranging from 0 to 22.9 and temperatures ranging from 14.5 to 26.6 ºC, demonstrating their tolerance to a wide range of estuarine environmental conditions. There was a clear succession of the three species that was influenced by temperature and salinity. Blackfordia virginica was the dominant hydromedusae during the warmest months and occurred at very high abundance (up to 634 individuals.m-3 corresponding to 21.40 g.m-3 as wet weight). The seasonal evolution of the size distribution indicated an extended period of release of medusae by hydroid polyps, and rapid growth, covering the whole period of occurrence for B. virginica. Nemopsis bachei also was present during the warmer months but only locally common. In contrast, Maeotias marginata only occurred in low numbers during autumn and had not been previously detected in the Gironde Estuary. Non-native jellyfishes clearly represent a prominent component of the Gironde Estuary, and additional work is needed to understand the potential impacts on the structure and functioning of entire zooplankton community.
(Aquatic Invasions. vol. 11, n° 1798-6540, pp. 397-409, 22/06/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR EABX, IRSTEA, EDF R&D LNHE, EDF R&D, EDF [E.D.F.]
Tracking the turbidity maximum zone in the Loire Estuary (France) based on a long-term, high-resolution and high-frequency monitoring network
A unique dataset of turbidity from 7 years of continuous monitoring at six stations, distributed evenly along a 62-km long transect, is presented to discuss, for the first time, the present-day dynamics of the turbidity maximum zone (TMZ) in the Loire Estuary. This system is considered one of the largest macrotidal, hyper-turbid estuaries of the European coast, mainly as the result of intense engineering works in the last two centuries. Besides accurate TMZ tracking, from tidal to multi-annual time scales, the high temporal and spatial resolution of measurements allows us to address TMZ aspects scarcely reported in the literature on estuarine sedimentary dynamics. In the Loire Estuary, TMZ moves upstream during periods of low discharge and its upstream boundary may reach up to 62 km from the mouth. The TMZ displacement is faster during its downstream flushing by river floods than during its upstream migration by tidal pumping (respectively 1.6 km day-1 and 0.9 km day-1 during 2011). However, the expulsion of the TMZ from the upper reaches requires higher discharge levels than its installation (respective discharge thresholds of 497-1034 m3 s-1 and 300-360 m3 s-1). This is due to the presence of mobile mud remaining after the TMZ presence, as confirmed by clockwise turbidity-discharge hysteresis patterns. While the installation threshold barely varies over years, the expulsion threshold is higher during years with a more concentrated and persistent TMZ. The interannual variability of the TMZ concentration and persistence is explained by the water volume transported during the previous high discharge period and the duration of the low discharge period, respectively, as recently shown for the Gironde Estuary, leading to a better understanding of TMZ features in macrotidal estuaries. The summer-averaged river flow is introduced as a hydrological indicator of the upstream boundary of the TMZ. In the context of global change, these three discharge-based indicators of TMZ behavior provide powerful tools to assess future scenarios.
(Continental Shelf Research. vol. 117, n° 0278-4343, pp. 1-11, 22/06/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, EDF [E.D.F.]
Experimental Assessment of the Effects of Temperature and Food Availability on Particle Mixing by the Bivalve Abra alba Using New Image Analysis Techniques
The effects of temperature and food addition on particle mixing in the deposit-feeding bivalve Abra alba were assessed using an experimental approach allowing for the tracking of individual fluorescent particle (luminophore) displacements. This allowed for the computations of vertical profiles of a set of parameters describing particle mixing. The frequency of luminophore displacements (jumps) was assessed through the measurement of both waiting times (i.e., the time lapses between two consecutive jumps of the same luminophore) and normalized numbers of jumps (i.e., the numbers of jumps detected in a given area divided by the number of luminophores in this area). Jump characteristics included the direction, duration and length of each jump. Particle tracking biodiffusion coefficients (Db) were also computed. Data originated from 32 experiments carried out under 4 combinations of 2 temperature (Te) and 2 food addition (Fo) levels. For each of these treatments, parameters were computed for 5 experimental durations (Ed). The effects of Se, Fo and Ed were assessed using PERmutational Multivariate ANalyses Of VAriance (PERMANOVAs) carried out on vertical depth profiles of each particle mixing parameter. Inversed waiting times significantly decreased with Ed whereas the normalized number of jumps did not, thereby suggesting that it constitutes a better proxy of jump frequency when assessing particle mixing based on the measure of individual particle displacements. Particle mixing was low during autumn temperature experiments and not affected by Fo, which was attributed to the dominant effect of low temperature. Conversely, particle mixing was high during summer temperature experiments and transitory inhibited by food addition. This last result is coherent with the functional responses (both in terms of activity and particle mixing) already measured for individual of the closely related clam A. ovata originating from temperate populations. It also partly resulted from a transitory switch between deposit- and suspension-feeding caused by the high concentration of suspended particulate organic matter immediately following food addition.
(PLoS ONE. vol. 11, n° 1932-6203, pp. e0154270, 22/06/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
La dépoldérisation de l'Île Nouvelle : Trajectoires écologiques et sociétale d'une opération de renaturation
Les zones intertidales estuariennes – vasières et marais – sont le support de nombreux services écosystémiques parmi lesquels la dénitrification des eaux continentales, la défense contre les submersions et l'accueil de juvéniles de poissons. Si ces milieux ont considérablement régressé en Europe au terme d'un millénaire de poldérisation, un nombre croissant d'expériences volontaires de restauration des submersions tidales sur d'anciennes terres endiguées voient le jour depuis les années 1990. À vocation majoritairement environnementale et défensive, ces opérations de dépoldérisation sont diversement acceptées par les riverains, les citoyens et les acteurs économiques et institutionnels. Située dans la zone faiblement salée (oligohaline) de l'estuaire de la Gironde, l'île Nouvelle s'est partiellement dépoldérisée lors de la tempête Xynthia en février 2010, suite à la formation accidentelle d'une brèche dans sa digue de protection. Comparée à la plupart des autres sites dépoldérisés, elle est originale à la fois par son caractère insulaire et son histoire. Née de la fusion de deux îles qui ont été occupées par l'homme dès le début du XIXème siècle et valorisées par une succession de cultures (dont la vigne pendant près d'un siècle), l'île Nouvelle a été rachetée par le Conservatoire du Littoral en 1991. Sa gestion a été confiée au Conseil Départemental de la Gironde (CD33) qui y mène une politique de renaturation. Un projet de recherche multidisciplinaire de 3 ans (2012-2015), impulsé par le CD33, a permis de répondre à plusieurs questions soulevées par la dépoldérisation, en particulier le risque de disparition d'un territoire, les impacts environnementaux des échanges entre l’île et l’estuaire, les effets sur la biodiversité terrestre (végétation) et aquatique (poissons et macrocrustacés) et la perception par plusieurs catégories d'acteurs de cette politique originale de renaturation. La télédétection spatiale s'affirme comme un outil pertinent pour suivre le creusement d'un chenal principal d'érosion (coursive) et d'un réseau de chenaux secondaires ainsi que l'évolution de l’occupation de sol, contribuant ainsi à l’étude des dépôts de sédiments et du couvert végétal. En complément de mesures morpho- et hydro-sédimentaires, les données spatiales permettent de comprendre certains des processus de dépoldérisation conduisant à la reconstruction d’un marais estuarien et de définir des scenarii d’évolution de l’île. Échantillonnés de manière comparative entre la partie sud (endiguée) et la partie nord (dépoldérisée) de l'île Nouvelle, les peuplements de poissons et de crevettes sont profondément remaniés suite à la dépoldérisation: les espèces d'eau douce, pour la plupart introduites, régressent au profit des espèces migratrices et estuariennes. Des entretiens semi-directifs menés auprès de riverains et d'acteurs publics montrent une appropriation et des avis contrastés sur la dépoldérisation de l'île Nouvelle, découlant d'une expérience différente de l'île et de l'estuaire. Cette étude, grâce au couplage et à l’exhaustivité des approches menées, permet de répondre de manière concrète à plusieurs des enjeux écologiques et de gestion des usages terrestres et maritimes qui accompagnent les expériences – volontaires ou non – de dépoldérisation en zone estuarienne.
(pp. 41, 22/06/2026)
UR ETBX, IRSTEA, UR EABX, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Benthic stable isotope variability in the Trondheimsfjord during the last 50 years: Proxy records of mixing dynamics related to NAO
Benthic stable isotopes (d 18 O c and d 13 C c) in the Trondheimsfjord reliably reflect the prevailing hydrological conditions with regard to the distance to the fjord entrance and the local topography. At the fjord entrance the d 18 O c and d 13 C c variabilities record changes in the temperature of the North Atlantic Current (NAC), and in the delivery of terrigenous organic matter by the Norwegian Coastal Current (NCC) and the fjord estuarine circulation, respectively. In the inner fjord basins, the benthic stable isotope compositions are predominantly controlled by hydrological characteristics linked to internal mixing and the prevailing wind pattern. The fjord deep basins are relatively sheltered from erosion and both land and marine-derived sediments accumulate at very high rates indicating past regional climate and associated driving parameters. In the present study we discuss the recent variability (last 55 years) of the stable isotope compositions (oxygen and carbon) measured in calcite shells of the benthic foraminiferan Mel-onis barleeanus with regard to the changing influence of marine versus fresh water inputs and of the prevailing wind patterns. The relative influence of marine versus continental waters were analysed as well as the complex topography and the related hydrology of the Trondheimsfjord using sediment cores collected in three different settings along the fjord axis. The variability the of stable isotope compositions obtained from the sedimentary archives is compared with in situ instrumental measurements over the investigated time interval.
(Estuarine, Coastal and Shelf Science. vol. 172, n° 0272-7714, pp. 34-46, 22/06/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, BGR, UiT
Asari clam (Ruditapes philippinarum) in France: history of an exotic species 1972–2015
In 1972, France underwent an oyster (Crassostrea angulata) crisis and urgently needed to diversify its aquaculture. Thus, Asari clam (Ruditapes philippinarum) was introduced at that time for aquaculture purpose, concomitantly with the introduction of Pacific oyster (Crassostrea gigas). All Asari clam adults and spat originated from the same area (Puget Sound, WA, USA). After a promising start and the implementation of a national Research & Development program, Asari clam culture rapidly faced a series of concomitant handicaps: firstly, in spite the fact that cultural practices were optimized and locking points addressed, leasing ground availability was limited during the 1980s’ due to certain reluctance from oyster farmers to share their leases and/or diversify their activity; secondly, mortality events in the parks probably due to the spat quality, diseases and/or zootechnical errors and/or predation by triggerfish; and thirdly economical competition with Italian production rapidly increased, exacerbated by the occurrence of neonaturalized Asari clam populations and the resulting professional fishing. Meanwhile, European vs national regulations, concerning minimum legal shell length of clams devoted to the market, were unfavourable to France due to contrasted rules between the Mediterranean Sea and the Atlantic Ocean; eventually, several diseases impacted drastically clam populations. At the end of the 80’s in Northern part of Brittany (France), mass mortality occurred due to brown ring disease, later related to a prokaryote (Vibrio tapetis). Presently, the French production remains limited to 2 - 3000 metric tons, mainly based upon professional fishing on neonaturalized populations located in two sites (Arcachon bay and Morbihan Gulf). In Arcachon bay, a comprehensive population dynamics study demonstrated the concomitant effects of fishing activity and environmental characteristics on the population dynamics. A management model was developed to assess various scenarios mainly based on conservation measures (i.e. fishing area, and/or fishing licences number, and/or fishing period). Implementation of those recommendations has provided some encouraging results. However, Asari clam fitness remains poor: a genetic impoverishment due to population isolation was argued by fishermen, but transplant experiments demonstrated that these bivalves kept their plasticity, at least in terms of growth and condition index. Thus, several environmental factors were investigated as possible key parameters explaining low clam performances. Again, pathologies were pointed out and particularly the high pressure exerted by the protist Perkinsus sp. (perkinsosis). Moreover, a new pathology was discovered in 2005 in Arcachon bay, the brown ring disease. Although the etiological factor has not been confirmed, viral origin is suspected. A meta-analysis comparing Asari clam characteristics in Arcachon Bay with the international literature pointed out that their reduced condition index in this bay was likely resulting from combined unfavorable factors (e.g., diseases, trace elements). However, 30% of the condition index variability among sites at the worldwide level was explained by food availability (chlorophyll a concentration). A comparative morphometric studies on four populations of the French Atlantic coasts, using conventional shape analysis, also revealed significant relationships between morphometric ratios and environmental parameters (chlorophyll a concentrations and seawater temperature). Eventually, marine ecologists and state managers as well, must deal with conflictual goals: on one hand Asari clam is an important exploited bivalve in France, on the other hand, the species remains an exotic species which needs careful attention (e.g., European regulations on invasive species)
(Bulletin of Japan Fisheries Research and Education Agency. vol. 42, n° 2432-2830, pp. 35-42, 22/06/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, SGMM, IFREMER, IFREMER, LEMAR, IRD, IFREMER, UBO EPE, CNRS