Climatic facilitation of the colonization of an estuary by Acartia tonsa
Global change has become a major driving force of both terrestrial and marine systems. Located at the interface between these two realms, estuarine ecosystems are probably the place where both direct and indirect effects of human activities conspire together to affect biodiversity from phytoplankton to top predators. Among European estuarine systems, the Gironde is the largest estuary of Western Europe and many studies have provided evidence that it has been affected by a variety of anthropogenic stressors such as thermal and chemical pollution, physical alterations and exploitation, especially for maritime traffic. In such a context, species introduction is also a current major issue with the establishment of strong competitive species that could lead to ecosystem reorganization with potential decrease or even disappearance of native species. In the Gironde estuary, this hypothesis was proposed for the invasive shrimp species Palaemon macrodactylus as a decrease in the native species abundance was observed at the same time. Although species introduction often takes place via ballast water, the influence of climate-driven changes on the establishment of new species remains a key issue. The calanoid copepod Acartia tonsa, observed in the Gironde estuary for the first time in 1983, have since colonized most part of the estuary, reaching a level of abundance comparable to the dominant native species Eurytemora affinis. In this study, using both the concept of the ecological niche sensu Hutchinson (fundamental and realized niches) and statistical models, we reveal that the dynamics of the colonization of A. tonsa was facilitated by environmental conditions that have become closer to its environmental optimum with respect to temperature and salinity.
(PLoS ONE. vol. 8, n° 1932-6203, pp. e74531, 13/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LOG, INSU - CNRS, ULCO, CNRS, IRD [Ile-de-France]
Observations of waves' impact on currents in a mixed-energy tidal inlet : Arcachon on the southern French Atlantic coast
Coastal morphodynamic processes around tidal inlets in mixed-energy environments are particularly complex due to severe tide and wave conditions. Collecting data in this area is generally very challenging . Here we present the first hydrodynamic data collected in the outer inlet of the Arcachon lagoon, a mixed-energy inlet situated on the southern part of the French Atlantic coast. Data consist in vertical current profiles and sea surface elevations collected on the offshore edge of the ebb delta under various tidal and wave conditions. In particular data were collected during the severe Joachim storm associated to wave heights up to 8 m. Preliminary results indicate that current profiles, intensities and direction are very sensitive to wave conditions. Under energetic conditions, the vertical profile of currents become uniform and the longshore drift is enhanced (up to 1.5 m/s). Nevertheless data show that under severe wave conditions (Hm0> 6.0m) and despite high incidence of waves, the longshore drift is weaker (l< 1 m/s) than under ‘usual’ storm conditions associated to Hm 0= 4–5m. More surprisingly, directions of the longshore drift are not always consistent with wave incidence under those severe storm conditions and the cross-shore components are very weak while under less energetic conditions we observe intense offshore currents(upto 0.8 m/s).
(Journal of Coastal Research, n° 0749-0208, pp. p. 2053-2058, 13/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, PRODIG, UP1, IRD, EPHE, PSL, UP4, UPD7, CNRS, SHOM
North-south palaeohydrological contrasts in the central Mediterranean during the Holocene: tentative synthesis and working hypotheses
On the basis of a multi-proxy approach and a strategy combining lacustrine and marine records along a north- south transect, data collected in the central Mediterranean within the framework of a collaborative project have led to reconstruction of high-resolution and well-dated palaeohydrological records and to assessment of their spatial and temporal coherency. Contrasting patterns of palaeohydrological changes have been evidenced in the central Mediterranean: south (north) of around 40 N of latitude, the middle part of the Holocene was characterised by lake-level maxima (minima), during an interval dated to ca. 10 300-4500 cal BP to the south and 9000-4500 cal BP to the north. Available data suggest that these contrasting palaeohydrological patterns operated throughout the Holocene, both on millennial and centennial scales. Regarding precipitation seasonality, maximum humidity in the central Mediterranean during the middle part of the Holocene was characterised by humid winters and dry summers north of ca. 40 N, and humid winters and summers south of ca. 40 N. This may explain an apparent conflict between palaeoclimatic records depending on the proxies used for reconstruction as well as the synchronous expansion of tree species taxa with contrasting climatic requirements. In addition, south of ca. 40 N, the first millennium of the Holocene was characterised by very dry climatic conditions not only in the eastern, but also in the central- and the western Mediterranean zones as reflected by low lake levels and delayed reforestation. These results suggest that, in addition to the influence of the Nile discharge reinforced by the African monsoon, the deposition of Sapropel 1 has been favoured (1) by an increase in winter precipitation in the northern Mediterranean borderlands, and (2) by an increase in winter and summer precipitation in the southern Mediterranean area. The climate reversal following the Holocene climate optimum appears to have been punctuated by two major climate changes around 7500 and 4500 cal BP. In the central Mediterranean, the Holocene palaeohydrological changes developed in response to a combination of orbital, ice-sheet and solar forcing factors. The maximum humidity interval in the south-central Mediterranean started ca. 10 300 cal BP, in correlation with the decline (1) of the possible blocking effects of the North Atlantic anticyclone linked to maximum insolation, and/or (2) of the influence of the remnant ice sheets and fresh water forcing in the North Atlantic Ocean. In the north-central Mediterranean, the lake-level minimum interval began only around 9000 cal BP when the Fennoscandian ice sheet disappeared and a prevailing positive NAO-(North Atlantic Oscillation) type circulation developed in the North Atlantic area. The major palaeohydrological oscillation around 4500- 4000 cal BP may be a non-linear response to the gradual decrease in insolation, with additional key seasonal and interhemispheric changes. On a centennial scale, the successive climatic events which punctuated the entire Holocene in the central Mediterranean coincided with cooling events associated with deglacial outbursts in the North Atlantic area and decreases in solar activity during the interval 11 700-7000 cal BP, and to a possible combination of NAO-type circulation and solar forcing since ca. 7000 cal BP onwards. Thus, regarding the centennial-scale climatic oscillations, the Mediterranean Basin appears to have been strongly linked to the North Atlantic area and affected by solar activity over the entire Holocene. In addition to model experiments, a better understanding of forcing factors and past atmospheric circulation patterns behind the Holocene palaeohydrological changes in the Mediterranean area will require further investigation to establish additional high-resolution and well-dated records in selected locations around the Mediterranean Basin and in adjacent regions. Special attention should be paid to greater precision in the reconstruction, on millennial and centennial timescales, of changes in the latitudinal location of the limit between the northern and southern laeohydrological Mediterranean sectors, depending on (1) the intensity and/or characteristics of climatic periods/oscillations (e.g. Holocene thermal maximum versus Neoglacial, as well as, for instance, the 8.2 ka event versus the 4 ka event or the Little Ice Age); and (2) on varying geographical conditions from the western to the eastern Mediterranean areas (longitudinal gradients). Finally, on the basis of projects using strategically located study sites, there is a need to explore possible influences of other general atmospheric circulation patterns than NAO, such as the East Atlantic-West Russian or North Sea-Caspian patterns, in explaining the apparent complexity of palaeoclimatic (palaeohydrological) Holocene records from the Mediterranean area.
(Climate of the Past. vol. 9, n° 1814-9324, pp. 2043-2071, 13/04/2026)
LCE, CNRS, UFC, UBFC, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, PALEOCEAN, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, IMBE, AU, AMU, CNRS, CNRS, OCCR, UNIBE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, MSHE, CNRS, UFC, UBFC, GEOAZUR 6526, IRD, UPMC, UNS, INSU - CNRS, UniCA, CNRS, UNIROMA, GEOPS, UP11, CNRS, ISTO, BRGM, INSU - CNRS, UO, CNRS, UniPi, EAWAG, UNIMOL, M2C, UNICAEN, NU, INSU - CNRS, UNIROUEN, NU, CNRS, GEODE, UT2J, Comue de Toulouse, CNRS, D-ERDW, ETH Zürich, FSS
Benthic foraminifera from Capbreton Canyon revisited; faunal evolution after repetitive sediment disturbance
At a 650 m deep site in the axis of Capbreton Canyon an 18-cm-thick turbidite was deposited in December 1999. During subsequent campaigns, an almost monospecific fauna of the benthic foraminifer Technitella melo, considered as a pioneer species, was found in May 2000. In 2001 this fauna had disappeared and was replaced by an exceptionally rich fauna strongly dominated by the opportunistic species Bolivina subaenariensis. We present sedimentological, radionuclide and foraminiferal data of new cores, sampled in 2005 and 2011, taken with the aim to study the further evolution of the benthic ecosystem. Cores sampled in 2005 show that in the canyon axis a new, ca. 5 cm thick, turbidite has been deposited. The live benthic foraminiferal faunas were much poorer than in 2001, but still had a high dominance and low diversity, although less extreme than in 2001. We conclude that in the canyon axis, benthic foraminiferal faunas remain in an early stage of ecosystem colonization. It appears that the very thick 1999 turbidite marks an exceptional event. The uncommonly rich faunas observed in 2001 could be a response to the concentration of organic-rich material in the fine-grained top of this deposit. In 2011, cores were sampled at a slightly different site, on the lower canyon flank. The sedimentary sequence here is marked by the absence of coarse turbidite layers, although some levels show slightly increased grain size, and lower 210Pbxs activities, indicative of an admixture with advected older sediments. Live foraminiferal faunas are much more equilibrated, as shown by their higher diversity, lower dominance, and deeper penetration into the sediment. All these characteristics are indicative of a much more stable ecosystem. Dead faunas are present throughout the core, indicating that the levels with slightly elevated grain size are not typical turbidites resulting from hyperpycnal currents (which are characterized by levels barren of foraminifera) but denote other, more long-term sedimentary processes leading to the advection of older material, such as bottom nepheloid layers, or repetitive fine-grained turbidite deposits due to small-scale slumping. The comparison of live and dead fauna shows that at both sites, the foraminiferal turnover rates are fairly low. At the lower canyon flank site sampled in 2011, the foraminiferal faunas are renewed every 1.5–2 years. Such a fairly long foraminiferal lifespan corresponds to earlier estimates, but is surprisingly high for the opportunistic taxa that dominate the faunal assemblages in these unstable and food-enriched submarine canyon settings.
(Deep Sea Research Part II: Topical Studies in Oceanography. vol. 104, n° 0967-0645, pp. 319 - 334, 13/04/2026)
LPG-ANGERS, LPG, UA, UN UFR ST, UN, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Global biomass burning : a synthesis and review of Holocene paleofire records and their controls
(Quaternary Science Reviews. vol. 65, n° 0277-3791, pp. 5-25, 13/04/2026)
PACEA, UB, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, SAGES, UOR, CPCC, UOR, OCCR, UNIBE, UNIBE, LCE, CNRS, UFC, UBFC
Biodiversité marine : chapitre 6
A l'échelle du golfe de Gascogne et de ses zones côtières et littorales, les suivis de la biodiversité montrent d'importantes variations annuelles d'abondance e de répartition géographique des espèces en relation avec le climat. Les tendances actuelles montrent que la biodiversité va évoluer vers une augmentation de représentativité des espèces tempérées chaudes, une modification de la phénologies des espèces et de la productivité des écosystèmes.
(pp. 173-188, 13/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR EPBX, IRSTEA, LERAR, COAST, IFREMER, IRSTEA, IFREMER, MNHN, UPMC
Benthic and Planktic Foraminifera as Indicators of Late Glacial to Holocene Paleoclimatic Changes in a Marginal Environment: An Example from the Southeastern Bay of Biscay.
Benthic and planktic foraminiferal assemblages from two sediment cores (2,000 m depth, 44 degrees 33'N, 2 degrees 45'W) were analyzed to first compare modern and dead faunas and next to study changes in the hydrology of the southeastern Bay of Biscay (SE BoB) over the last 12.8 cal ka BP. Considering benthic ecosystem characteristics, the first part of the paleorecord (12.8-7.6 cal ka BP) is composed of laminated sediments that may have resulted from turbiditic overflow events, whereas occurrences of transported species (e. g. Nonionella sp., Cassidulina carinata) attest of continental influence at the core location. After 7.6 cal ka BP, the sediment becomes bioturbated concomitantly to the stabilization of the sea-level. The benthic foraminiferal fauna is largely dominated by Uvigerina peregrina suggesting a high seasonality with seasonal pulsed organic matter fluxes to the seafloor. On the other hand, the planktic foraminiferal composition indicates that surface water masses were under the influence of the polar front in the early record, which retreated at about 11.5 cal ka BP. The early Holocene is characterized by relatively warm and stratified water masses at 8.4-4.8 cal ka BP. The last 4.8 cal ka BP records a gradual sea surface water cooling trend and enhanced foraminiferal production from similar to 2.6 cal ka BP until present. The early (12.8-10.5 cal ka BP) and late (2.3-1.7 cal ka BP) Holocene are characterized by the presence of the planktic species Globigerinoides ruber probably caused by intrusions of the Iberian Poleward Current (IPC), and a negative state of the North Atlantic Oscillation (NAO).
(Acta Protozoologica. vol. 52, n° 0065-1583, pp. 161-180, 13/04/2026)
BIAF, UA, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, PALEOCEAN, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Use of integrative samplers for the determination of the efficiency of wastewater advanced treatments: case of pharmaceuticals compounds
Introduction. The general objective of the ECHIBIOTEB research program (“Innovating tools for sampling, chemical and biological analyses for the diagnosis of wastewater advanced tertiary treatments and sludge treatments”, 2011-2014, financed by the French National Research Agency) is introduced in a previous presentation. Briefly it consists in developing new tools for the determination of the efficiency of advanced treatments, especially for the sampling. This presentation will describe the potential of Polar Organic Chemical Integrative Sampler (POCIS) for the monitoring of pharmaceuticals in water, compared to grab sampling. Analytical methodology. Until today, two campaigns were performed in order to follow the efficiency of ozone (O3) treatment, alone and coupled with Granular Activated Carbon (GAC) by exposing 20 POCIS before and after the wastewater treatment during 28 days. Each triplicate, associated to a field blank, is dedicated to a kind of analysis (pharmaceuticals, alkylphenols, and biological analysis, for example). In parallel, grab samplings were achieved after 0, 14 and 28 days of POCIS exposition in order to compare these two approaches. 104 molecules belonging to several therapeutic classes such as antibiotics, -blockers, antineoplastics, antivirals, phosphodiesterase type 5 inhibitor (PDE 5), analgesics, broncholidators, non-steroidal anti-inflammatory and psychiatric drugs, lipid regulators and stimulants, were analysed. Therefore, in order to determine the in-situ rate constants of exposed POCIS, 3 Reference Performance Compounds (PRC) were previously added in the adsorbant phase: salbutamol-d3, caffeine-13C and desisopropylatrazin-d5 (DIA d5) and laboratory calibration on pharmaceuticals were performed. Solid Phase Extractions (SPE) were carried out on the different samples depending on compound classes and, then, analyses were performed by liquid phase chromatography coupled with tandem mass spectrometry (LC-MS/MS). Results. Among targeted compounds, 39 molecules were not detected in any samples of wastewater, in the dissolved phase and 32 molecules in any POCIS samplers. As illustrated in Figure 1a, concentrations upstream from the treatments are higher than those downstream; whatever is the nature of wastewater process. Betablockers, macrolides, psychiatric drugs, fluoroquinolones and quinolones are the most abundant compounds upstream these processes and downstream, only two classes (Betablockers and stimulants) remain present as relatively high concentrations. Therefore, it seems that GAC and GAC+O3 treatments involve a drastic reduction of micropollutant concentrations in wastewaters. Regarding concentrations determined in the adsorbant phase of passive samplers (Figure 1b), the tendency between upstream and downstream coincides well with the one of wastewater samples, in terms of pharmaceutical abundances and between samples too. Figure 2 shows that the number of detected targeted compounds depends on the place of sampling (up or downstream) and on the way of sampling (POCIS vs. grab sampling). For the process using granular activated carbon, based on the measurements of 103 molecules, 13 extra compounds are detected in the adsorbant phase of POCIS compared to the dissolved phase, upstream and downstream the process. Until today, regarding the analysis of 93 molecules for ozone+GAC process, the trend is also observed with the detection of 23 and 17 extra compounds, upstream and downstream respectively. These results show the real interest of this sampling mode by the improvement of methodology sensitivity. Laboratory calibration of passive samplers allow to determine rate constants for more than 25 of target compounds and so, to compare directly the results between integrative and grab sampling in terms of concentrations. This methodology of sampling reveals its interest for the quantification of targeted compounds and has been also applied to the analysis of non-targeted compounds in order to complete the knowledge on the efficiency of such process. The presence of pharmaceuticals and non-targeted compounds could explain the potential toxicity of these samples (wastewater and POCIS extracts). Acknowledgements. The authors wish to thank the program ECOTECH-ECHIBIOTEB, the Aquitaine Region and the European Union (CPER A2E project) for financial support. Europe is moving in Aquitaine with the European Regional Development Fund.
(pp. 36, 13/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR MALY, IRSTEA
Zebrafish: A model animal for analyzing the impact of environmental pollutants on muscle and brain mitochondrial bioenergetics.
Mercury, anthropogenic release of uranium (U), and nanoparticles constitute hazardous environmental pollutants able to accumulate along the aquatic food chain with severe risk for animal and human health. The impact of such pollutants on living organisms has been up to now approached by classical toxicology in which huge doses of toxic compounds, environmentally irrelevant, are displayed through routes that never occur in the lifespan of organisms (for instance injecting a bolus of mercury to an animal although the main route is through prey and fish eating). We wanted to address the effect of such pollutants on the muscle and brain mitochondrial bioenergetics under realistic conditions, at unprecedented low doses, using an aquatic model animal, the zebrafish Danio rerio. We developed an original method to measure brain mitochondrial respiration: a single brain was put in 1.5mL conical tube containing a respiratory buffer. Brains were gently homogenized by 13 strokes with a conical plastic pestle, and the homogenates were immediately used for respiration measurements. Skinned muscle fibers were prepared by saponin permeabilization. Zebrafish were contaminated with food containing 13μg of methylmercury (MeHg)/g, an environmentally relevant dose. In permeabilized muscle fibers, we observed a strong inhibition of both state 3 mitochondrial respiration and cytochrome c oxidase activity after 49 days of MeHg exposure. We measured a dramatic decrease in the rate of ATP release by skinned muscle fibers. Contrarily to muscles, brain mitochondrial respiration was not modified by MeHg exposure although brain accumulated twice as much MeHg than muscles. When zebrafish were exposed to 30μg/L of waterborne U, the basal mitochondrial respiratory control ratio was decreased in muscles after 28 days of exposure. This was due to an increase of the inner mitochondrial membrane permeability. The impact of a daily ration of food containing gold nanoparticles of two sizes (12 and 50nm) was investigated at a very low dose for 60 days (40ng gold/fish/day). Mitochondrial dysfunctions appeared in brain and muscle for both tested sizes. In conclusion, at low environmental doses, dietary or waterborne heavy metals impinged on zebrafish tissue mitochondrial respiration. Due to its incredible simplicity avoiding tedious and time-consuming mitochondria isolation, our one-pot method allowing brain respiratory analysis should give colleagues the incentive to use zebrafish brain as a model in bioenergetics. This article is part of a Directed Issue entitled: Bioenergetic dysfunction, adaptation and therapy.
(International Journal of Biochemistry and Cell Biology. vol. 45, n° 1357-2725, pp. 16-22, 13/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IBGC, UB, CNRS
Carbon and suspended sediment transport in an impounded alpine river (Isère, France)
Carbon and total suspended sediment (TSS) loads were investigated from April 2006 to March 2008 in the mountainous watershed of the Isère River, French Alps (5570 km2). The river bed has been highly impounded for hydroelectricity production during the last century. Hydraulic flushes are managed every year to prevent TSS storage within upstream dams. The Isère River has been instrumented for high-frequency monitoring of water, TSS by turbidity and carbon (organic, inorganic, dissolved and particulate) in order to evaluate the impact of natural floods and hydraulic flushes on annual loads. Annual TSS load which was estimated between 1.3 and 2.3 MT y−1 (i.e. 233 to 413 T km−2 y−1) highlighted the high erodibility of the Isère watershed. Annual carbon load was estimated between 173 103 T y−1 and 199 103 T y−1 (i.e 31 to 36 T km−2 y−1). About 80% of the annual carbon loads were inorganic. The impact of hydraulic flushes on annual loads appeared limited (less than 3% for annual TSS load and about 1.5% for annual carbon load), whereas the most important natural flood event contributed to 20% of the annual TSS load and 10% of the annual carbon load.
(Hydrological Processes. vol. 27, n° 0885-6087, pp. 2498-2508, 13/04/2026)
LTHE, OSUG, UJF, Grenoble INP, INSU - CNRS, IRSTEA, USMB [Université de Savoie] [Université de Chambéry], CNRS, IRD, INSU - CNRS, INPG, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ISTO, BRGM, INSU - CNRS, UO, CNRS, SISYPHE, UPMC, EPHE, PSL, PSL, CNRS, EDF [E.D.F.]