Étude de la sensibilité des juvéniles de moule perlière (Margaritifera margaritifera) à une contamination métallique, aux nutriments et à la température
Margaritifera margaritifera ou la moule perlière est un mollusque bivalve d’eau douce aujourd’hui en danger critique d’extinction en Europe. La pollution environnementale est considérée comme l’un des facteurs majeurs impliqués dans la disparition des populations de M. margaritifera. Cette thèse vise à étudier l’impact d’une contamination métallique (aluminium Al, arsenic As, cadmium Cd, cuivre Cu et nickel Ni) et des nutriments responsables du processus d’eutrophisation (nitrates NO3- et ortho-phosphates PO43-) sur le stade juvénile de M. margaritifera, considéré comme l’un des stades les plus sensibles de l’espèce. Afin d’appréhender les potentiels effets du changement climatique, l’effet de la température a également été étudié. Dans un premier temps, les seuils de toxicité aigüe des différents contaminants et nutriments, ont été déterminés. Les résultats ont montré une grande tolérance des juvéniles à des concentrations en contaminants largement supérieures à celles retrouvées dans l’environnement, et dépendante de l’âge des individus. Les effets des différents facteurs étudiés seuls ou en mélange ont ensuite été évalués lors de tests de toxicité chronique par le biais de plusieurs biomarqueurs : l’expression des gènes, la bioaccumulation des métaux et le comportement des organismes, dont la méthode a été développée dans cette thèse. Au niveau moléculaire, la contamination métallique a révélé un impact sur la modulation des gènes de plusieurs fonctions biologiques comme l’apoptose, la détoxication, la réparation de l’ADN ou encore le métabolisme mitochondrial. De plus, ces travaux ont permis de confirmer la capacité des juvéniles à accumuler ces éléments traces métalliques (ETMs), notamment le Cd, le Cu et l’Al, contrairement à l’As qui s’accumule peu dans les tissus. L’impact des nutriments au niveau moléculaire n’est observé que lorsqu’ils sont étudiés en combinaison et notamment à une température de 22°C, soit 6 degrés de plus que la température moyenne annuelle de la Dronne. L’effet de la température étudiée seule, a montré un impact sur l’expression des gènes en relation avec le stress oxydant et la réparation de l’ADN lorsque les juvéniles sont exposés à une température de 26°C, alors qu’à 21°C, aucune modification n’a pu être observée. L’exposition des organismes à plusieurs contaminants en mélange (As, Cu, Al, NO3- et PO43-) combinée à différentes températures (16, 26 et 30°C) a permis de mettre en évidence l’impact d’une augmentation de la température sur l’expression des gènes du métabolisme mitochondrial, du stress oxydant, de la détoxication et de l’immunité, et sur le comportement des juvéniles, en termes de distance parcourue. Finalement, cette étude a permis d’évaluer la sensibilité des jeunes stades de vie de la moule perlière et d’améliorer nos connaissances sur l’impact de certains ETMs, des nutriments responsables de l’eutrophisation des milieux aquatiques et de la température sur cette espèce, à différentes échelles de l’organisme. Ces travaux suggèrent que l’augmentation de la température causée par le changement climatique, combinée à la présence de contaminants dans les cours d’eau pourrait accentuer le déclin des populations de moule perlière.
(19/05/2021)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Advances of sclerochronology research in the last decade
Over the past decade, sclerochronological research has continued to develop rapidly and is diversifying with respect to methods, taxa, geographic coverage as well as temporal depth. Chonologically aligned environmental records from bivalves, gastropods, coralline algae, corals, and many other periodically formed biogenic hard parts are integrated to build networks across broad spatial domains and trophic levels. Replication and exact dating ensure that environmental signals are fully preserved and facilitate the integration among chronologies as well as observational records of climatic and biological phenomena. The proliferation of chronologies promises to usher in a new era of synthesis that integrates tropical to polar environments and links with other high-resolution archives such as tree-ring chronologies to assess broad-scale couplings between the ocean and atmosphere across different latitudes. An increasing number of studies also applies sclerochronological methods to fossils from the more distant past and studies paleoclimate variability in deep time. At the same time, rapid advances are being made in developing, optimizing and validating proxies from isotopes, trace and minor elements, and ultrastructures (aka microstructures) of periodically growing skeletal hard parts to reveal new parameters of environmental variability from these exactly dated frameworks. Beyond the importance for paleoclimatology, information recorded in such archives is of increasing relevance to ecology and management to provide insights on life history, population connectivity, productivity, and disentangling the impacts of natural and anthropogenic environmental and climate change. Likewise, environmental information from archaeological samples are providing new insights into long-term interactions between climate variability and dynamics of past human societies. This review paper provides insights into advances in the field of sclerochronology, with an emphasis on mollusks, including trends in the analysis of growth patterns, development and interpretation of proxies, diversity of taxa used in sclerochronological research, as well as the geographic and temporal coverage of sclerochronological research.
(Palaeogeography, Palaeoclimatology, Palaeoecology. vol. 570, n° 0031-0182, 15/05/2021)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Synchronies, changements technologiques et climatiques : nouveaux apports méthodologiques dans l'étude du sud-ouest de la France à la fin du Paléolithique moyen
Évaluer des synchronies et diachronies entre des changements climatiques et culturel ou technologiques est un prérequis pour comprendre le possible impact des changements environnementaux sur les groupes humains. Face aux fluctuations climatiques, ils se sont adaptés, déplacés voire même ont disparu. La recherche de synchronies durant la fin du Paléolithique moyen jusqu'au début du Paléolithique supérieur (~80-35 ka avant le présent), est entravée par la limite de la technique de datation par radiocarbone, les larges incertitudes chronologiques affectant les archives archéologiques et paléoclimatiques, mais également par les faibles résolutions des données paléoclimatiques, si disponibles. En Europe, la période entre ~ 50-35 ka est marquée par la disparition l'Homme de Néandertal et l'arrivée de l'Homme anatomiquement moderne (HAM). Afin de déterminer si les changements climatiques et environnementaux ont été concomitants avec les transitions des techno-complexes lithiques, plusieurs axes de réflexions et outils sont mis en oeuvre. Il s'agit premièrement de reconstruire les paléoenvironnements et paléoclimats dans le sudouest de la France, région abondamment riche en études sur les sites archéologiques des Paléolithiques moyen et supérieur. L'apport des techniques de datation par luminescence au-delà de 40 ka parait nécessaire pour l'élaboration d'une chronologie plus robuste des archives paléoenvironnementales et climatiques. A cela, s'ajoute une nouvelle approche de modèles d'âgeprofondeur. Enfin, une reconstextualisation des changements de techno-complexes lithiques est essentielle, par le développement d'une base de données chronologique fiable et critique pour la période d'étude. C'est seulement après l'amélioration des deux archives, archéologique et paléoclimatique, qu'il sera alors possible d'appréhender ou non les moyens d'adaptations des groupes préhistoriques face aux changements environnementaux et climatiques.
(03/05/2021)
IRAMAT-CRP2A, IRAMAT, UTBM, UO, UBM, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
A nation-wide monitoring campaign of 53 contaminants of emergent concern in surface waters and sediments (EMNAT 2018): occurrence and PNEC exceedance evaluation
(03/05/2021)
INERIS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ISA, UCBL, INC-CNRS, CNRS
Variations and significance of Mg/Sr and 87Sr/86Sr in a karst cave system in southwest China
The geochemical compositions of cave drip water and speleothems such as Mg, Sr, Mg/Ca, Sr/Ca, and ⁸⁷Sr/⁸⁶Sr are considered to be responsive to changes in the local climate and hydrological conditions. Systematic monitoring was performed on the Mg and Sr contents, Mg/Sr ratio and ⁸⁷Sr/⁸⁶Sr of soil, soil water, cave drip water, and the active speleothems (AS) in Furong Cave in Chongqing, southwest China, during 2009–2018 (A.D). The results were interpreted in conjunction with the changes in the ⁸⁷Sr/⁸⁶Sr ratios to explore the main sources and controlling factors of Sr and other trace elements in drip water. (1) Due to the decrease in winter and spring rainfall, the residence time of water in the soil was prolonged, which resulted in increasing of Mg and Sr concentrations and ⁸⁷Sr/⁸⁶Sr ratios in soil water. It indicates that the trace element contents of soil water reflect seasonal changes of the rainfall. (2) The Mg and Sr contents were higher in drip water than in the soil water, as well as the ⁸⁷Sr/⁸⁶Sr of the cave drip-water was closer to that of the bedrock, which indicates that the overlying bedrock was the main source of the trace elements in the drip water and the speleothems in Furong Cave. (3) Mg contents and Mg/Sr ratios in drip water and AS showed decreasing trend, which may be affected by the shorter water-rock contact time due to the increasing annual rainfall in the monitoring period. (4) The Sr contents in AS might be affected by the growth rate of AS because of the similar increasing trend. (5) The Mg and Sr contents and the Mg/Sr ratios of the drip water and AS did not exhibit seasonal variations due to the mixing of the fissure water and complex hydrology condition of the overlying bedrock, however, the geochemical indexes (Mg and Mg/Sr ratio) showed an opposite trend to the annual rainfall variation. In short, this study highlights the responses of the changes of Mg, Sr and Mg/Sr ratios of drip water and AS to the rainfall on the multi-year timescale, which contributes critical insights into the paleoclimate interpretation of proxies of speleothems in the cave with hundreds of meters’ thick bedrock.
(Journal of Hydrology. vol. 596, n° 0022-1694, pp. 126140, 01/05/2021)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Reading the diaries of life – Current advances in sclerochronological research
(Palaeogeography, Palaeoclimatology, Palaeoecology. vol. 570, n° 0031-0182, pp. 110373, 01/05/2021)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Tidal turbines in the estuarine environment: from identifying optimal location to environmental impact
Estuaries that feature large tidal ranges (macrotidal) have recently received attention for their potential to generate energy by tidal stream turbines. As estuaries are delicate ecosystems and often have large human populations residing on their shores, determining where to place the turbines and how they will impact the hydrodynamics and sediment transport of these systems is vital to their successful implementation. The aim of this study is to provide a framework for assessing an estuary for turbine placement, including determining how the turbines will impact the environment (focusing on the physics), and examining other items that could peripherally affect the tidal turbine farm location or impact. This work was carried out using the Gironde Estuary as a case study and included a combination of in-situ data collection and numerical modeling. In terms of the turbine farm impact on the hydrodynamics and Suspended Sediment Concentration (SSC), results showed that the inclusion of a farm reduced currents up to 10% and decreased SSC up to 15 mg/l. The decrease in SSC was due to the attenuated current velocities decreasing friction velocity and thus near bottom generated turbulence that suspends bottom sediment. Over time, the decreased SSC will lead to sediment accumulation and new bottom features.
(Renewable Energy. vol. 169, n° 0960-1481, pp. 700-713, 01/05/2021)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Role of Atmospheric Indices in Describing Inshore Directional Wave Climate in the United Kingdom and Ireland
Improved understanding of how our coasts will evolve over a range of time scales (years-decades) is critical for effective and sustainable management of coastal infrastructure. A robust knowledge of the spatial, directional and temporal variability of the inshore wave climate is required to predict future coastal evolution and hence vulnerability. However, the variability of the inshore directional wave climate has received little attention, and an improved understanding could drive development of skillful seasonal or decadal forecasts of coastal response. We examine inshore wave climate at 63 locations throughout the United Kingdom and Ireland (1980–2017) and show that 73% are directionally bimodal. We find that winter-averaged expressions of six leading atmospheric indices are strongly correlated (r = 0.60–0.87) with both total and directional winter wave power (peak spectral wave direction) at all studied sites. Regional inshore wave climate classification through hierarchical cluster analysis and stepwise multi-linear regression of directional wave correlations with atmospheric indices defined four spatially coherent regions. We show that combinations of indices have significant skill in predicting directional wave climates (R2 = 0.45–0.8; p < 0.05). We demonstrate for the first time the significant explanatory power of leading winter-averaged atmospheric indices for directional wave climates, and show that leading seasonal forecasts of the NAO skillfully predict wave climate in some regions.
(Earth's Future. vol. 9, n° 2328-4277, pp. e2020EF001625, 01/05/2021)
SBMS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LOPS, IRD, IFREMER, INSU - CNRS, UBO EPE, CNRS, EMPS
Molecular Impacts of Dietary Exposure to Nanoplastics Combined or Not with Arsenic in the Caribbean Mangrove Oysters (Isognomon alatus)
Nanoplastics (NPs) are anthropogenic contaminants that raise concern, as they cross biological barriers. Metals’ adsorption on NPs’ surface also carries ecotoxicological risks to aquatic organisms. This study focuses on the impacts of three distinct NPs on the Caribbean oyster Isognomon alatus through dietary exposure. As such, marine microalgae Tisochrysis lutea were exposed to environmentally weathered mixed NPs from Guadeloupe (NPG), crushed pristine polystyrene nanoparticles (PSC), and carboxylated polystyrene nanoparticles of latex (PSL). Oysters were fed with NP-T. lutea at 10 and 100 µg L−1, concentrations considered environmentally relevant, combined or not with 1 mg L−1 pentoxide arsenic (As) in water. We investigated key gene expression in I. alatus’ gills and visceral mass. NP treatments revealed significant induction of cat and sod1 in gills and gapdh and sod1 in visceral mass. As treatment significantly induced sod1 expression in gills, but once combined with any of the NPs at both concentrations, basal mRNA levels were observed. Similarly, PSL treatment at 100 µg L−1 that significantly induced cat expression in gills or sod1 in visceral mass showed repressed mRNA levels when combined with As (reduction of 2222% and 34%, respectively, compared to the control). This study suggested a protective effect of the interaction between NPs and As, possibly by decreasing both contaminants’ surface reactivity.
(Nanomaterials. vol. 11, n° 2079-4991, 01/05/2021)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Evaluating the impact of Mediterranean overflow on the large-scale Atlantic Ocean circulation using neodymium isotopic composition
(Palaeogeography, Palaeoclimatology, Palaeoecology. vol. 570, n° 0031-0182, pp. 110359, 01/05/2021)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, GEOPS, INSU - CNRS, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, CLIM, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA