Acquisition de tolérance par les biofilms périphytiques exposés aux pesticides en mélange
Dans notre étude, l'impact de pesticides en mélange est évalué sur des communautés périphytiques de rivière provenant d'un site exempt de contamination en pesticides (station amont) et d'un site subissant des pollutions chroniques en pesticides (station aval) à travers l'utilisation d'extraits d'échantillonneurs passifs de type POCIS (Polar Organic Chemical Integrative Sampler). Le rendement photosynthétique optimal (Fv/Fm), la fluorescence de chlorophylle a (chla), le poids sec (PS) et la matière sèche sans cendre (MSSC) sont suivis pendant les 14 jours d'expérimentation. D'autre part, la tolérance acquise des communautés initiales puis l'évolution de cette tolérance en fonction de la levée ou du maintien de la « pression toxique » sont évaluées face aux extraits de POCIS (EP). A J14, une diminution significative du PS et de la MSSC chez les biofilms avals exposés aux EP par rapport aux biofilms avals non exposés est observée ainsi qu'une augmentation significative de la chla pour les biofilms amont exposés aux EP à J7 et J14 par rapport aux biofilms amont non exposés. Au temps initial, les biofilms provenant des stations amont et aval présentaient des niveaux de tolérance différents, avec des CE25 (Fv/Fm) de 0.06±0.01 et 0.48±0.14EP respectivement. Après 14 jours d'exposition aux EP, une différence de sensibilité pour les concentrations les plus élevées est apparue au regard du Fv/Fm et de la chla entre les biofilms avals exposés ou non aux EP. Les 3 concentrations les plus élevées entrainent une inhibition significative du Fv/Fm pour les biofilms non exposés aux EP (51±13, 21±15 et 15±10% respectivement, % du contrôle), alors que seules les 2 concentrations les plus élevées ont un impact sur Fv/Fm pour les biofilms exposés aux EP (43±2 et 25±3% respectivement, % du contrôle). Pour la concentration la plus élevée, la quantité de chla des biofilms exposés aux EP est significativement plus importante par rapport aux non exposés (222±7.53 et 204±5.43 % du contrôle respectivement). Les différents descripteurs testés révèlent un impact des EP sur les capacités photosynthétiques des communautés (chla, Fv/Fm) ainsi qu'un impact sur la croissance globale du biofilm (PS, MSSC). L'important écart de tolérance initiale entre les biofilms amont et aval répond bien au concept PICT développé par Blanck et al. en 1988, de plus les différences dans l'évolution de la tolérance face au maintien ou non de l'exposition aux pesticides sur 14 jours permettent d'appréhender les réponses des communautés naturelles face à un changement de pression de contamination. Notre étude souligne donc l'intérêt de l'utilisation des POCIS combinée aux approches de type PICT dans le domaine de l'écotoxicologie ainsi que leur potentiel dans le cadre de développements de nouveaux outils de diagnostic de la qualité des eaux.
(pp. 1, 27/06/2026)
UR REBX, CEMAGREF, UR MALY, CEMAGREF, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
HFNI Valvometry : a tool based on recording bivalve ethology to monitor environmental health in coastal seawaters
(27/06/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LMBA, UBS, UBO EPE, CNRS
The 7–13 March 2006 major Saharan outbreak: Multiproxy characterization of mineral dust deposited on the West African margin
Mineral dust deposits were collected at Mbour, Senegal, throughout the spring of 2006 and especially during the well‐documented March 7–13 large Saharan dust outbreak. During this 7‐day period, significant changes in mass flux, grain‐size, clay mineralogy and Sr and Nd isotopic compositions were recorded, indicating distinct provenances for the dust transported and deposited during and outside the event. All these terrigenous proxies, as well as freshwater diatom taxa, also showed significant temporal variations during the outbreak, implying contributions from at least two different provenance regions. Tri‐dimensional back‐trajectories and satellite imaging enabled us to link those distinct signatures to regions increasingly to the southeast within a large area covering Mauritania, Mali and southern Algeria, identified by the Total Ozone Mapping Spectrometer (TOMS) as the main source of the prominent winter/spring plume over the tropical Atlantic. The multiproxy characterization of the March 7–13 dust fall therefore enables us to typify the terrigenous signature of two different regions supplying dust off West Africa, and provide valuable clues for the interpretation of Northeastern Tropical Atlantic Ocean dust sedimentary records in terms of changes in provenance regions and transport systems. Additionally, because dust deposition data are scarce, flux and grain size data obtained in this study, among other parameters such as clay assemblages, provide important constraints for atmospheric transport models and dust deposition budget estimates in this area.
(Journal of Geophysical Research: Atmospheres. vol. 116, n° 2169-897X, pp. D18210, 27/06/2026)
LOG, INSU - CNRS, ULCO, CNRS, IRD [Ile-de-France], CNRS, MPIC, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, NIOZ, LOA, INSU - CNRS, CNRS, LISA (UMR_7583), INSU - CNRS, UPD7, UPEC UP12, CNRS, IMAGO
In situ giant clam growth rate behavior in relation to temperature : a one-year coupled study of high-frequency noninvasive valvometry and sclerochronology
The life history of 15 giant clams, Hippopus hippopus, was studied in situ in the southern lagoon of New Caledonia; growth rate and animal behavior were studied both by sclerochronology and high-frequency noninvasive (HFNI) valvometry. Electrodes glued on each valve of each specimen recorded the shell-gaping behavior at 0.6-Hz frequency. A nonparametric regression model was used to model clam behavior. The daily increment thickness in the inner layer of five representative clams was measured. H. hippopus has its valves open during the day and partly closed during the night all year round, and shell growth is continuous. The cumulative growth using both techniques was similar, as was the mean daily thickness increment. The occurrence of one increment per day in H. hippopus shell was measured by valvometry. The five sclerochronological profiles were highly similar. Shell growth was significantly correlated to rising sea surface temperature (SST), up to 27 degrees C. At the solar maximum, gaping behavior and increment thickness became erratic. SST- and solar irradiance-related stress could be related to physiological oxidative stress triggered by zooxanthellae symbionts. In the present context of globally increasing SST, our data indicate that the giant clams H. hippopus could live beyond their thermal comfort limits in summer in New Caledonia.
(Limnology and Oceanography. vol. 56, n° 0024-3590, pp. 1940-1951, 27/06/2026)
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, LMBA, UBS, UBO EPE, CNRS
Presence of Palaemon macrodactylus in a Europe estuary: evidence for a successful invasion of the Gironde (SW France)
Palaemon macrodactylus, an exotic shrimp native to the northwest Pacific Ocean, has been recorded in many estuaries along the Atlantic coast of Europe since the late 1990’s. In this study, a regular monthly survey, held since 1992 of the middle section of the Gironde estuary, revealed this species’ rapid and full colonization of the system since its appearance in samples during summer 1998. In the Gironde, the population of P. macrodactylus is self-sustaining and the species is now established there. Our study highlights two important elements that might explain its successful colonization: its ability to quickly invade a niche under-exploited by the similar native species and its greater reproductive output. The species’spatio-temporal distribution in relation to environmental variables was studied and compared with that of the native species P. longirostris. The exotic species was shown to mainly inhabit the polyhaline and mesohaline section of the estuary, which are sections generally under-exploited by females of the native species. Furthermore, fecundity analysis and larval abundance survey results revealed a higher potential fecundity and a greater proportion of larvae and juvenile stages for P. macrodactylus in the natural environment.
(Aquatic Invasions. vol. 6, n° 1798-6540, pp. p. 301 - p. 318, 27/06/2026)
UR EPBX, CEMAGREF, UR MALY, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Capacités de décontamination métallique et évolution des formes tératogènes de Planothidium lanceolatum après une contamination expérimentale au cadmium
Cette étude vise à évaluer la viabilité des formes tératogènes et leurs capacités de reproduction après une contamination métallique afin de prédire un éventuel retour vers une population diatomique de forme normale. Nous avons travaillé sur une espèce fréquemment rencontrée dans les hydrosystèmes français : Planothidium lanceolatum. Une première phase expérimentale a consisté à contaminer des monocultures en Cd à 20 ou 100 ag/L pendant 21 jours. Cela a permis de mettre en évidence l'induction de formes tératogènes en réponse à la contamination en Cd. L'identification des tératologies indique que le Cd affecterait en premier lieu le raphé, les stries puis les valves. Les déformations de l'aire centrale et les tératologies multiples semblent se produire en second lieu. A la suite de la contamination, une seconde phase expérimentale s'est déroulée durant 28 jours en condition de décontamination. Elle a permis de démontrer les capacités de dépuration en Cd de Planothidium lanceolatum. Les demies-vies du Cd calculées sont apparues relativement courtes : environ 6 jours pour la condition initialement contaminée à 100 ag/L. Par ailleurs, la décontamination des monocultures a permis de mettre en évidence une disparition progressive des formes tératogènes, néanmoins restée incomplète en fin d'expérience. Ainsi, après 28 jours de décontamination, les déformations des stries et du raphé restaient encore statistiquement supérieures aux conditions témoins dans les deux conditions initialement contaminées à 20 et 100 ag/L. Des études complémentaires intégrant d'autres espèces de diatomées seraient donc nécessaires pour comparer les différentes capacités de dépuration métallique et de retour vers des formes normales. Enfin, une phase de décontamination plus longue et progressive permettrait d'estimer le temps nécessaire pour un rétablissement complet de la population et imiterait de façon plus représentative une éventuelle amélioration chimique du milieu comme observé in situ.
(pp. 1, 27/06/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR REBX, CEMAGREF
Distribution of parasites in their second intermediate host, the cockle Cerastoderma edule: community heterogeneity and spatial scale
We studied the spatial heterogeneity of infection of the marine bivalve Cerastoderma edule (cockle) by trematode parasites at 5 different scales in Banc d’Arguin, France. At the km-scale, the communities of trematodes differed among stations in terms of species composition and specific abundance. Infection heterogeneity was likely due to the occurrence of the definitive host and the conditions of transmission (water parameters). At the 100 m scale, trematode species richness was similar among stations, but specific trematode abundances differed. The most significant variable in terms of explaining trematode infection heterogeneity was the presence of the first intermediate host. At the 10 m scale, the distance at which parasite abundance diminished varied according to trematode species. When an intense source of trematode larvae (cercariae) emission was suspected, this abundance was maintained within ca. 20 m. Outside this area, parasite abundance progressively dropped. We found a higher aggregation in parasite distribution at the 100 m scale than at the 10 m scale using a community aggregation measure. At the cm-scale, the parasite species richness was similar in all cockles but parasite abundance differed in relation to distance when the parasites were shed by a sedentary host compared to a motile host. Observed differences of infection could also be due to intrinsic factors (life history, immune system) as suggested by an experimental infestation where cockles challenged in similar conditions displayed different parasite loads. We demonstrated that high heterogeneity of parasite infection in cockles should be taken into account in studies concerning the role of parasites in ecosystems.
(Marine Ecology Progress Series. vol. 428, n° 0171-8630, pp. 187-199, 27/06/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Census and analysis of zooplankton metadata of the French coasts since 1955
In the framework of the Marine Strategy Framework Directive (MSFD), and for the first time, a census and analysis of the available metadata on zooplankton along the French coasts have been conducted (for both long term time series and short term oceanographic cruises). This study provided a comprehensive examination of zooplankton within the French metropolitan coastal system, i.e., the North Sea, the English Channel, the Atlantic Ocean and the Mediterranean Sea.The investigation revealed a wide disparity in the spatial distribution of studies highlighting some well sampled areas as well as other regions quite unexplored. In addition, this approach also exposed the heterogeneity in zooplankton sampling methods and taxonomic determination levels. The wide variety of sampling methods defined the whole zooplankton community, from the smallest fauna (such as crustacean nauplii) to the largest (such as euphausiids) to the most delicate (gelatinous forms). Unfortunately, the possibilities for cross analysis of Zooplankton meta data census 12 the different data are limited. This paper presents a preliminary analysis of the data available for meta analysis (in term of sampling method and taxonomic determination). In order to understand current and future environmental fluctuations (climate change, ocean acidification, anthropogenic pollution and persistent overfishing), it is essential to identify and analyze all the biological data collected in the different French marine areas. This indispensable first step is crucial for defining the environmental status of marine waters.The nexus of our results provides recommendations for a standardization of procedures to be followed in subsequent studies of zooplankton, specifically sampling strategies, sampling methods and taxonomic determinations
(Journal of Oceanography. vol. 4, n° 0916-8370, pp. 11-37, 27/06/2026)
LOG, INSU - CNRS, ULCO, CNRS, IRD [Ile-de-France], LOV, OOVM, UPMC, INSU - CNRS, CNRS, UPMC, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ULCO, LOPB, INSU - CNRS, CNRS
Acoustic turbulence measurements of near-bed suspended sediment dynamics in highly turbid waters of a macrotidal estuary
Sediment-turbulence interactions near the bed are still poorly understood in highly turbid estuaries, especially in the presence of fluid mud layers. This results primarily from the difficulty in measuring colocated velocity and suspended sediment concentration (SSC) at sufficiently high rate to resolve small turbulent flow scales. In this paper, we show how a set of commercial acoustic and optical backscattering systems known as ADCPs, ADVs and OBSs, can be deployed and used in a complementary way to perform large-scale profilings of tidal current and SSC combined with high-resolution velocity and SSC measurements in the highly turbid near-bed zone. The experiment was done in the Gironde estuary (France) which is well known for its turbidity maximum zone characterized by high SSC values, above 1 g/l near the surface. A first simple inversion method is proposed to convert the backscattered acoustic intensity measured with ADV into SSC data in the highly turbid near-bed zone. Near-bed SSC data from the OBS are used to compensate for the important acoustic sediment attenuation effect at an acoustic frequency of 6 MHz. No a priori knowledge of acoustic backscattering properties of mud suspensions is required with this calibration procedure. We obtain an attenuation coefficient for mud suspensions of 0.28m2/kg at 6 MHz leading to a good agreement between the SSC timeseries from the three ADV receivers and the OBS over the entire tidal cycle. The obtained SSC data are then analyzed with respect to the near-bed velocity, Reynolds shear stress and turbulent kinetic energy (TKE) timeseries in order to identify the relevant sediment transport processes during the tidal cycle. Significant differences in bed shear stress and TKE levels are found between ebb and flood stages with effects on near-bed sediment dynamics. During the ebb, maximum levels of tidal current, bed shear stress and TKE are associated with a reduction of near-bed sediment concentration (from 400 g/l down to 100 g/l). Bed liquefaction process is assumed to occur at this moment with the presence of highly concentrated mud layer and a possible lutocline at a distance of less than 20 cm above the bed. During the first 1.5 h of flood, turbulent activity remains moderate. The near-bed flood current is then inhibited very abruptly while a sudden increase in SSC occurred above the bed. Assuming that the ADV is able to estimate relevant turbulent erosion fluxes, the co-located velocity and SSC are multiplied and compared with settling flux measurements made onboard under quiescent water conditions. The mean sediment settling fluxes (averaged over 3min) increase with SSC and are in relative good coherence with fluxes in quiescent water below the hindered regime, for SSC below 15 g/l. Reducing averaging time from 3 min to 30 s allows to increase the range of turbulent fluxes and SSC values, up to 99 g/l. At this scale, fluxes keep increasing quasi-linearly at higher SSC, suggesting the inhibition (delay or reduction) of the hindered settling regime as previously shown by Gratiot et al. (2005) from laboratory experiments. However, the 3-min averaged concentration field remained too low to conclude definitively on the effectiveness of such a process. Further analysis conducted at higher SSC regimes and under fully verified equilibrium are necessary.
(Continental Shelf Research. vol. 31, n° 0278-4343, pp. S36-S49, 27/06/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEGI, UJF, Grenoble INP, CNRS, LTHE, OSUG, UJF, Grenoble INP, INSU - CNRS, IRSTEA, USMB [Université de Savoie] [Université de Chambéry], CNRS, IRD, INSU - CNRS, INPG, CNRS, M2C, UNICAEN, NU, INSU - CNRS, UNIROUEN, NU, CNRS
Mesurer les micropolluants dans les eaux usées brutes et traitées. Protocoles et résultats pour l'analyse des concentrations et des flux
Le projet AMPERES a permis une évaluation des concentrations et des flux de 127 substances prioritaires et émergentes dans les eaux usées brutes, les eaux traitées et les boues pour différentes filières d'épuration représentatives du parc français par une démarche de prélèvement et d'analyse rigoureuse et validée. Au total, 21 stations d'épuration (STEP) ont été sélectionnées pour étudier les traitements biologiques secondaires, plusieurs procédés tertiaires et les filières de traitement des boues. Des prélèvements moyen-24h des eaux résiduaires ont été réalisés par temps sec au cours de 2 à 3 jours consécutifs en entrée et en sortie de STEP. Nous avons développé et appliqué des protocoles analytiques spécifiques pour la mesure des substances en phase dissoute et particulaire, sensibles et adaptés aux matrices des STEP qui présentent une forte complexité. Les substances présentes aux plus fortes concentrations (>1 µg/L) dans les eaux usées brutes sont le DEHP, certains composés organiques volatiles (COV), des retardateurs de flammes (diphényléthersbromés ou PBDE), les alkylphénols (4-NP et 4-t-OP et leurs produits de dégradation, et presque tous les métaux. Les niveaux de concentration dans les eaux usées brutes et les flux spécifiques montrent une spécificité des rejets des STEP de zone urbaine par rapport aux STEP de zone rurale pour certaines substances d'origine industrielle (alkylphénols, COV, chloroalcanes, dichlorophénol, bisphénol A et quelques métaux). Dans les eaux traitées par traitement biologique, même si une réduction significative des concentrations par rapport à l'eau usée brute est généralement observée, 12 substances prioritaires, 10 autres substances organiques et la plupart des métaux ont encore été retrouvées à des concentrations moyennes supérieures à 0,1 µg/L. Des concentrations supérieures à 1 µg/L ont été fréquemment mesurées pour plusieurs métaux, le DEHP et certains produits de dégradation (4-NP1EC et AMPA). Pratiquement toutes les substances qui ont été quantifiées dans les eaux usées brutes, l'ont aussi été dans les boues, même si elles sont parfois mesurées à de très faibles concentrations, en particulier pour les substances les plus hydrophiles (pesticides). Cet article présente également les données exploitées sous la forme de flux spécifiques (µg/j/hab) émis vers les milieux récepteurs.
(TSM. Techniques Sciences Méthodes. vol. 1-2, n° 0299-7258, pp. 25-43, 27/06/2026)
RiverLy, INRAE, UR MALY, CEMAGREF, UR REVERSAAL, INRAE, CNRS, LPTC, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CIRSEE