Persistent Organic Pollutants in a marine bivalve on the Marennes-Oléron Bay and the Gironde Estuary (French Atlantic coast) -Part 1: Bioaccumulation
The aim of this study was to determine 1) the relevance of using the Pacific oyster Crassostrea gigas as a sentinel organism, at a juvenile stage, for polycyclic aromatic hydrocarbon (PAH) and persistent organic pollutant (polychlorobiphenyls, PCBs, polybromodimethylethers, PBDEs, and organochlorine pesticides, OCPs) contamination, 2) the potential levels of chemical organic contamination in the Marennes-Oleron Bay, and their potential sources 3) the potential influence of physiological or environmental factors on contaminant body burdens in oysters. To this end, juvenile oysters purchased from a oyster hatchery were transplanted to a reference site, in Bouin, and to different transplantation sites in the Marennes-Oléron Bay, the first oyster production area in France, and in the Gironde Estuary, the biggest estuary in Occidental Europe. Transplantations were done during summer and winter. Whole oyster soft tissues from each site were analyzed for PAHs, PCBs, PBDEs and OCPs. Results obtained with a transplantation period of 3 months suggest that the C. gigas, at the juvenile stage, is a relevant sentinel organism for short-term contamination for these contaminants. In addition, no significant effects of physiological factors on contaminant body burdens were observed. A principal component analysis performed with chemical body burdens allowed them to be separated into three groups: 1) the reference site, 2) Les Palles (LP) and Boyard (BOY) in winter and 3) all the other sites. The group of LP and BOY was clearly defined by the levels of PAHs and OCPs, suggesting higher levels of contamination of these chemical compounds on these sites, potentially due to local contamination sources. In addition, no relevant effects of physiological or environmental factors on contaminant body burdens were observed. Results suggest also a predominance of contaminants related to agricultural activities along the Marennes-Oléron Bay, and therefore, further studies on the presence of pesticides in this region should be considered.
(Science of the Total Environment. vol. 514, n° 0048-9697, pp. 500-510, 26/10/2026)
PUJ, LIENSs, INSU - CNRS, ULR, CNRS, UB, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Bacciger bacciger (Trematoda: Fellodistomidae) infection effects on wedge clam Donax trunculus condition
Wedge clams Donax trunculus inhabit high-energy environments along sandy coasts of the northeastern Atlantic Ocean and the Mediterranean Sea. Two sites were sampled monthly, one in Morocco (Mehdia), where the density was normal, and one in France (Biscarosse), where the density was very low. We tested the hypothesis that the difference in density between the sites was related to infection by the trematode parasite Bacciger bacciger. Identity of both the parasite and the host were verified using anatomical and molecular criteria. Parasite prevalence (i.e. the percentage of parasitized clams) was almost 3 times higher at Biscarosse. At this site, overall prevalence reached 32% in July and was correlated with the migration of several individuals (with a prevalence of 88%) to the sediment surface. After this peak, prevalence decreased rapidly, suggesting death of parasitized clams. The deleterious effect of B. bacciger on wedge clams was also supported by our calculations indicating that the weight of the parasite made up to 56% of the total weight of the parasitized clams. However, condition indices of trematode-free clams were also lower in Biscarosse than in Mehdia or other sites, suggesting that other factors such as pollutants or microparasites (Microcytos sp.) may alter wedge clam population fitness in Biscarosse.
(Diseases of Aquatic Organisms. vol. 111, n° 0177-5103, pp. 259-267, 26/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UM5
Atmospheric reactions of 9,10-anthraquinone
The probably carcinogenic compound 9,10-anthraquinone is mainly existing in the atmosphere in the particulate phase and is often detected and measured among other oxygenated PAHs in atmospheric samples. Its fate, once released or formed in the atmosphere, still remains unknown. In this work, heterogeneous chemical oxidation processes of 9,10-anthraquinone were investigated with ozone (O 3), nitrogen dioxide (NO 2) and hydroxyl radical (OH). The study of 9,10-anthraquinone adsorbed on silica particles showed no reactivity with O 3 and NO 2. On the other hand, the reaction with OH radicals was observed and led to the formation of 1-hydroxy-9,10-anthraquinone, another oxidation product recognized as possibly carcinogenic to humans. This study showed that reactions with ozone and nitrogen dioxide are unlikely to contribute to atmospheric degradation of 9,10-anthraquinone, whereas reactions with OH radicals could be involved in 9,10-anthraquinone degradation processes, even if such reaction is probably very slow under ambient conditions.
(Chemosphere. vol. 107, n° 0045-6535, pp. 1-6, 26/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, INERIS
Echantillonneurs passifs : évaluation de l’exposition des biofilms aux mélanges de pesticides, et du risque écotoxique dans les cours d’eau
La contamination généralisée des cours d’eau par les pesticides, généralement en mélanges et à concentrations relativement faibles, requiert la prise en compte dans le diagnostic de la complexité de l’exposition. Le développement récent de l’échantillonnage passif des contaminants a permis d’une part de mieux considérer la diversité des contaminants présents dans l’environnement, et d’abaisser leurs limites de détection, fournissant ainsi un panorama plus exhaustif de la contamination réelle. Le biofilm est une communauté complexe, composée de microalgues, de bactéries, de champignons, de protozoaires, etc. enchâssés dans une matrice polysaccharidique. Son utilisation en écotoxicologie revêt un haut degré de pertinence environnementale, comparé aux espèces modèles utilisées traditionnellement. Elle permet de mieux comprendre et prédire les impacts réels de contaminants pour l’écosystème, bien mieux que l’extrapolation de résultats déconnectés de la complexité des conditions de milieu (diversité des organismes, et de leurs relations). Le modèle biofilm a ainsi été utilisé avec succès dans de nombreuses études écotoxicologiques au laboratoire, utilisant des contaminants seuls ou en combinaisons simples (binaires, ternaires) de substances. Cependant, la qualification du risque écotoxique associé aux mélanges de contaminants est difficilement envisageable par ce biais, la multiplicité des mixtures possibles (en termes de composition et de concentrations) empêchant de tester toutes les combinaisons susceptibles d’être rencontrées in situ. Nous proposons ici de présenter les avancées récentes permises par le couplage entre échantillonnage passif et écotoxicologie, pour la mesure du potentiel toxique dans les milieux aquatique, et pour la mise en ½uvre d’expérimentations plus réalistes environnementalement.
(pp. 2, 26/10/2026)
UR EABX, IRSTEA, UR MALY, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Méthodes phytobenthiques cours d’eau (Réunion et Antilles) : Cadre général et méthodologique
Pour favoriser la mise en application de la DCE dans les DOM, des programmes locaux de développement de bio-indicateurs ont été entrepris à partir de 2008 sous la maîtrise d’ouvrage principale des gestionnaires locaux des hydrosystèmes (Offices de l’Eau et DEALs), avec des participations financières complémentaires émanant, selon le cas, du niveau national (Ministère de l’Outre-Mer, ONEMA), de l’Union Européenne (FEDER) et d’une part de financement propre souvent apportée par les équipes participant à la réalisation concrète des programmes. Dans ce cadre, le consortium Asconit-Irstea a pris en charge, entre 2008 et 2013, la réalisation de programmes de mise au point de nouveaux indices diatomiques des cours d’eau à la Réunion et aux Antilles et autofinancé, selon le cas, de 25 à 30 %.du coût total de chacun des projets. Les démarches Réunion et Antilles ont suivi des cheminements méthodologiques relativement parallèles et comparables sur le plan de la démarche biomathématique mise en oeuvre. A partir des données taxonomiques et abiotiques obtenues dans le cadre de 7 à 8 campagnes d’échantillonnage de terrain, des référentiels conséquents, atteignant au final 345 doublets de données exploitables à la Réunion et 607 aux Antilles, ont pu être constitués et faire l’objet de diverses analyses biomathématiques de données. Celles-ci se sont organisées en 5 étapes spécifiques d’investigation : 1) une biotypologie visant, à partir de la composition des assemblages, à repérer leur structuration sous les forçages naturels et sous l’emprise des pressions anthropiques ; 2) Une phase d’analyse exploratoire des données abiotiques (ACP complète ) visant à repérer l’organisation des données et les gradients principaux rencontrés au niveau physico-chimie et chimie de l’eau ; 3) Une analyse canonique des correspondances (ACC complète) visant à repérer la co-structuration des données générales d’environnement et des assemblages floristiques ; 4) une analyse canonique des correspondance restreinte, selon le cas, à 9 ou 10 variables physico-chimiques fortement influencées par les activités anthropiques (ACC restreinte), qui a permis de formaliser un gradient composite multimétrique d’anthropisation (GCMA) assis à la fois sur les données abiotiques et sur la matrice de réponse des assemblages diatomiques ; 5) le calcul du profil de qualité des espèces intervenant dans le calcul des futurs indices diatomiques, après seuillage sur un double critère d’occurrence et d’abondance relative minimale dans au moins un relevé, suivi de la formulation de l’indice. Il a ainsi été mis au point 2 versions successives d’IDR (Réunion) et d’IDA (Antilles) permettant au final de tirer parti de l’ensemble des données devenues mobilisables sur ces DOM à la fin 2013 et de remédier aux défauts de jeunesse diagnostiqués sur leur première version. Ces indices fonctionnent sur un principe général de repérage de taxons d’alerte, qui contribuent à la dégradation de la note d’indice avec un poids différent selon la catégorie à laquelle ils appartiennent. Un système d’évaluation propre à chaque DOM a ensuite été élaboré, conduisant à la proposition d’une grille spécifique d’évaluation, exprimée en EQRs, par grand ensemble naturel de chacun de ces DOM (2 grands ensembles naturels à la Réunion, 2 pour les Antilles regroupées). Ces grilles sont utilisables au relevé et devront faire l’objet d’une adaptation spécifique pour une agrégation temporelle au site. Elles ont été intégrées à un projet de nouvel Arrêté d’Evaluation dont la parution est prévue début 2015.
(pp. 19, 26/10/2026)
UR EABX, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Effets de la qualité des sédiments de frayère sur le développement embryo-larvaire de l'esturgeon européen (Acipenser sturio)
Les embryons et larves d'esturgeon européen ont été exposés aux substrats de 2 frayères situées sur la Dordogne et la Garonne. Les individus exposés au substrat de La Réole (Garonne) présentent une augmentation du taux de malformation, une altération des capacités physiologique et natatoire.
(pp. 15, 26/10/2026)
UR EABX, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Benthic foraminifera from the deep-water Niger delta (Gulf of Guinea): Assessing present-day and past activity of hydrate pockmarks
We present ecological and isotopic (δ18O and δ13C) data on benthic foraminifera sampled from 4 deep-sea stations in a pockmark field from the deep-water Niger delta (Gulf of Guinea, Equatorial Atlantic Ocean). In addition, a series of sedimentological and (bio)geochemical data are shown to back up foraminiferal observations. All stations are located within 1.2km of each other, so prevailing oceanographic conditions can be assumed to be similar at each site. Two of the sites (GMMC-01 and GMMC-02) are located in a pockmark (named "pockmark A") where current methane seepages were recorded by ROV observations. A third station (GMMC-03) is located in the topographic depression interpreted as a collapsed pockmark (named "pockmark B"). The fourth site (GMMC-04) is a reference station, without evidence of past or present seepages. Our observations show that degraded organic matter with low bio-availability is present at all stations with a preferential burial of organic compounds in topographic depressions (GMMC-03 station). Authigenic aragonite is abundant in surface sediments at stations GMMC-01 and -02. Its precipitation is likely related to high rates of methane oxidation during past seep events in episodically active pockmark A. In contrast, the absence of anaerobic methanotrophic Archaea (ANME) during the sampling period (November 2011) suggests that only moderate sulphide and methane oxidation take place close to the sediment-water interface. Compared to the reference site GMMC-04, living foraminifera at the collapsed and episodically active pockmarks show minor changes in terms of diversity, standing stocks and faunal composition. However, the δ13C signal of living and dead (but well-preserved) foraminiferal species (Ceratobulimina contraria, Melonis barleeanus, Uvigerina peregrina) is depleted in the episodically active pockmark A compared to the other stations. Overgrowth of authigenic carbonate on altered foraminifera generates an important shift to lower δ13C values. Dead faunas carry a complex time-averaged message, integrating taphonomic gains and losses related to the temporal variability of gas emission. They reveal major faunal differences that may be useful to detect gas hydrate seepages in different pockmark stages. © 2014 Elsevier Ltd.
(Deep Sea Research Part I: Oceanographic Research Papers. vol. 94, n° 0967-0637, pp. 87-106, 26/10/2026)
BIAF, UA, IPREM, UPPA, INC-CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, EGID, LASIRE, INC-CNRS, CNRS, LEP, EEP, IFREMER, IFREMER, AWI
Competition, facilitation and environmental severity shape the relationship between local and regional species richness in plant communities
Understanding the relative contribution of local and regional processes to local species richness is an important ecological question and a subject of controversy between macroecologists and community ecologists. We test the hypothesis that the contribution of local and regional processes is dependent on environmental conditions and that the eff ect of regional processes should be the highest in communities from intermediate positions along environmental severity gradients due to the importance of facilitation. We used the recently developed log-ratio method to analyze the relationship between local species richness (LSR) and regional species richness (RSR) for 13 plant communities from 4 habitat types of France (coastal sand dunes, oceanic heathlands, alpine grasslands, lowland calcareous grasslands). Each habitat type wassplit in 3 – 4 communities using multivariate analyses to identify the relative importance of stress, disturbance, competition, and facilitation functioning within the 13 communities. We found that the LSR/RSR relationship was highly dependent on environmental conditions with saturated communities occurring more frequently than unsaturated communities highlighting the relative importance of local drivers on species richness. We argued that competition was most likely the main source of community saturation whilst facilitation likely contributed to enhancing the importance of the regional species pool for all habitat types. However, the eff ect of facilitation might be stronger in the disturbed than in the stressed systems because unsaturated curves were only observed in the former conditions. In extreme conditions of disturbance LSR was only controlled by the intensity of disturbance. Th is eff ect was not observed in extreme stress conditions. Our study provides support for the emerging balance theory that both local and regional processes are important in nature with their relative contribution depending on environmental conditions. Additionally, this synthesis strongly suggests that facilitation contributes to an important process – the influence of regional species pool on local species richness.
(Ecography. vol. 37, pp. 1-11, 26/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LECA, UJF, USMB [Université de Savoie] [Université de Chambéry], CNRS, SAJF, UJF, CNRS, ECOBIO, UR, INEE-CNRS, CNRS, CNRS, ONF, IEU, UZH
Abnormal ovarian DNA methylation programming during gonad maturation in wild contaminated fish
There is increasing evidence that pollutants may cause diseases via epigenetic modifications. Epigenetic mechanisms such as DNA methylation participate in the regulation of gene transcription. Surprisingly, epigenetics research is still limited in ecotoxicology. In this study, we investigated whether chronic exposure to contaminants experienced by wild female fish (Anguilla anguilla) throughout their juvenile phase can affect the DNA methylation status of their oocytes during gonad maturation. Thus, fish were sampled in two locations presenting a low or a high contamination level. Then, fish were transferred to the laboratory and artificially matured. Before hormonal treatment, the DNA methylation levels of the genes encoding for the aromatase and the receptor of the follicle stimulating hormone were higher in contaminated fish than in fish from the clean site. For the hormone receptor, this hypermethylation was positively correlated with the contamination level of fish and was associated with a decrease in its transcription level. In addition, whereas gonad growth was associated with an increase in DNA methylation in fish from the clean site, no changes were observed in contaminated fish in response to hormonal treatment. Finally, a higher gonad growth was observed in fish from the reference site in comparison to contaminated fish.
(Environmental Science and Technology. vol. 48, n° 0013-936X, pp. 11688--11695, 26/10/2026)
µVIS X-ray Imaging Centre, LPTC, UB, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR EABX, IRSTEA, ISM, UB, INC-CNRS, CNRS, BOREA, UNICAEN, NU, MNHN, IRD, SU, CNRS, UA, INRS
Preface "The changing Arctic and Subarctic environment: proxy- and model-based reconstructions of Holocene climate variability in the northern North Atlantic
This special issue originates from the EU FP7-Marie Curie initiative "CASE" (The Changing Arctic and Subarctic Environment), an Initial Training Network (ITN) on marine biotic indicators of recent climate changes in the high latitudes of the North Atlantic (http://caseitn.epoc.u-bordeaux1.fr/). This four-year project (April 2010-March 2014) implemented multidisciplinary research initiatives aiming at assembling palaeoclimate data from the Holocene through recent field programmes in the Nordic Seas, and at integrating palaeoclimate information with modern biological and climate modelling data. Associated objectives were to recruit and train a new generation of European polar scientists with expertise on the Nordic Seas, and to develop a network of European experts in polar research to build structures focused on long-term collaboration in Arctic science. Together with the Arctic Ocean, the Nordic Seas and the Barents Sea have shown unprecedented changes in physical and chemical conditions in recent decades, which directly influence the ecosystem structure and processes. The extreme sensitivity of the northern North Atlantic to climate changes is related to the intricate connection, within this oceanic realm, of cryospheric (ice sheets and sea ice), atmospheric (winds related to strong gradients in sea-level pressures), and oceanic processes (through the opposing poleward flow of Atlantic water and southward flow of polar waters). The recent decline in seasonal sea ice extent is of particular concern as it modulates the reflection of incoming solar radiation, and influences the exchanges of heat and moisture between the surface ocean and the atmosphere. Moreover, sea ice also plays a central role in the efficiency of shelf (brines) and deep ocean convection processes, thus influencing the climate on a global scale. Decadal to millennial scale reconstructions of Holocene climate and environments from archives, such as marine sediment cores, and from palaeoclimate modelling hold keys to a better evaluation of the magnitude and implications of the ongoing warming with regard to the full range natural variability of the climate system. This special issue addresses some of the key questions raised by the CASE project and related to the present polar amplification of climate change: -Is the present global warming and its amplification in the Arctic and Subarctic domains a unique event on the scale of the Earth recent history (last 10 000 years)? -How do past decadal-to centennial-scale natural climate changes, as recorded in marine sediments and ice cores, stand in the context of the present human-induced modulation of climate? -How did Holocene variability in key physical elements affect the structure and diversity of the planktonic ecosystem in the Arctic and Subarctic domains?
(Climate of the Past. vol. 10, n° 1814-9324, pp. 589-590, 26/10/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UvA, LMD, INSU - CNRS, X, IP Paris, ENPC, SU, CNRS, ENS-PSL, PSL