Unprecedented coring performance with the upgraded Research Vessel Marion Dufresne
(Past Global Changes Magazine. vol. 24, n° 2411-605X, pp. 27, 25/10/2026)
CLIMAG, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, CNRS, PALEOCEAN, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
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, pp. 32984, 25/10/2026)
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
Monitoring the state of the spawning ground for future return of Acipenser sturio in the Gironde
Cette présentation synthétise les résultats des effets des contaminants organiques et minéraux présents sur les frayères et évalue la tolérance oxy-thermique des embryons et jeunes larves
(pp. 29, 25/10/2026)
UR EABX, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, INRA
Evaluation of spectral methods for high-frequency multiannual time series in coastal transitional waters: advantages of combined analyses: Tests of spectral analysis on coastal time series
High-frequency monitoring is currently a major component in the management and research of the coastal system responses to ongoing global changes. This monitoring is essential in tidal systems to address the multiscale variability of physico-chemical parameters. The analysis of the resulting multiscale, nonlinear, non-stationary and noisy time series requires adequate techniques; however, to date, there are no standardized methods. Spectral methods might be useful tools to reveal the main variability time scales, and thus their associated forcings. The most widely used methods in coastal systems are Lomb-Scargle Periodogram (LSP), Singular Spectral Analysis (SSA), Continuous Wavelet Transform (CWT), and Empirical Mode Decomposition (EMD), but their relevance for high-frequency, long-term records is still largely unexplored. In this article, these spectral methods are tested and compared using a high-frequency 10-yr turbidity dataset in the Gironde estuary. Advantages and limitations of each method are evaluated on the basis of five criteria: (1) efficiency for incomplete time series, (2) appropriateness for time-varying analysis, (3) ability to recognize processes without complementary environmental variables, (4) capacity to calculate the relative importance of forcings, and (5) capacity to identify long-term trends. SSA is the only analysis method to satisfy all the criteria, even with 70% missing data. Combining methods is also a promising strategy; i.e., SSA1LSP for better recognition of processes; CWT1SSA and EMD1CWT for short-term (seasonal) and long-term (>1 yr) analysis, respectively. The purpose of this methodological framework is to serve as a reference for future postprocessing of data from monitoring programs in coastal waters.
(Limnology and Oceanography: Methods. vol. 14, n° 1541-5856, pp. 381-396, 25/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Abrupt shifts in the Gironde fish community: an indicator of ecological changes in an estuarine ecosystem
For decades, global climate change has directly and indirectly affected the structure and function of ecosystems. Abrupt changes in biodiversity have been observed in response to linear or sudden modifications to the environment. These abrupt shifts can cause long-term reorganizations within ecosystems, with communities exhibiting new functional responses to environmental factors. Over the last 3 decades, the Gironde estuary in southwest France has experienced 2 abrupt shifts in both the physical and chemical environments and the pelagic community. Rather than describing these shifts and their origins, we focused on the 3 inter-shift periods, describing the structure of the fish community and its relationship with the environment during these periods. We described fish biodiversity using a limited set of descriptors, taking into account both species composition and relative species abundances. Inter-shift ecosystem states were defined based on the relationship between this description and the hydro-physico-chemical variables and climatic indices defining the main features of the environment. This relationship was described using generalized linear mixed models on the entire time series and for each inter-shift period. Our results indicate that (1) the fish community structure has been significantly modified, (2) environmental drivers influencing fish diversity have changed during these 3 periods, and (3) the fish-environment relationships have been modified over time. From this, we conclude a regime shift has occurred in the Gironde estuary. We also highlight that anthropogenic influences have increased, which re-emphasizes the importance of local management in maintaining fish diversity and associated goods and services within the context of climate change.
(Marine Ecology Progress Series. vol. 549, n° 0171-8630, pp. 137-151, 25/10/2026)
UR EABX, IRSTEA, IFREMER, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Groenland. Climat, Ecologie, Société
(pp. 300, 25/10/2026)
LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, LCE, CNRS, UMLP, CEFE, UPVM, INRA, Montpellier SupAgro, EPHE, PSL, UM, CNRS, IRD [Occitanie], IRD, Montpellier SupAgro, CEARC, UVSQ, 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, 25/10/2026)
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, 25/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, SGMM, IFREMER, IFREMER, LEMAR, IRD, IFREMER, UBO EPE, CNRS
Is herbicide toxicity on micro-algae influenced by the natural Dissolved Organic Matter (DOM)?
Les microalgues, en tant que producteurs primaires, sont à la base des réseaux trophiques aquatiques : elles peuvent donc être directement impactées par les herbicides. Dans l’environnement aquatique, la matière organique dissoute (MOD) peut également influencer les microalgues. La présente étude avait pour but d’étudier l’impact de la MOD naturelle (provenant du Bassin d’Arcachon) sur la toxicité de trois herbicides (irgarol (I), diuron (D) et S-métolachlore (S)), seuls et en mélange, pour deux micro-algues marines: Chaetoceros calcitrans (Cc) et Tetraselmis suecica (Ts), en cultures monospécifiques en laboratoire. Après une exposition de six jours à chaque herbicide (I0,05 et I0,5 µg.L-1; D0,05 et D0,5 µg.L-1; S0,5 et S5 µg.L-1) et à deux mélanges (M1: I0,05+D0,05+S0,5 et M2: I0,5+D0,5+S5), en présence ou non de MOD, les effets ont été évalués sur la croissance, l’efficacité photosynthétique, la quantité relative d’espèces réactives de l’oxygène et le contenu lipidique relatif. En l’absence de MOD, les conditions I0,5 et M2 ont significativement affecté les deux espèces : inhibition de la croissance et de l’efficacité photosynthétique et diminution du contenu lipidique relatif. Les impacts de M2 sur Cc ont été similaires aux effets induits par I0,5 ; en revanche pour Ts, la toxicité de M2 a été supérieure, suggérant une probable synergie entre les molécules. En présence de MOD, des effets significatifs de I0,5 et M2 ont également été observés sur les deux espèces : alors que les effets ont été amoindris en présence de MOD chez Cc, ils ont été amplifiés chez Ts. La présence de MOD naturelle a donc influencé la toxicité des herbicides de façon opposée chez les deux espèces. Ces résultats peuvent être expliqués partiellement par la complexation entre la MOD et les herbicides. En effet, des études ont montré que la MOD pouvait moduler la biodisponibilité des pesticides et des métaux selon la capacité des microalgues à pouvoir réaliser ou non de l’hétérotrophie (mécanisme favorisant la pénétration des molécules dans les cellules). Les variations de toxicité observées dans cette étude pourront être interprétées plus précisément avec les résultats des analyses chimiques en cours d’acquisition (MOD, herbicides et carbone organique dissous).
(pp. 26, 25/10/2026)
UR EABX, IRSTEA, IFREMER, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
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, 25/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS