The 4GFOR model – Coupling 4G early diagenesis and benthic foraminiferal ecology
(Marine Micropaleontology. vol. 170, n° 0377-8398, pp. 102078, 01/01/2022)
LPG, UM, UA, INSU - CNRS, CNRS, Nantes univ - UFR ST, Nantes Univ, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
How does the Southern Ocean palaeoenvironment during Marine Isotope Stage 5e compare to the modern?
(Marine Micropaleontology. vol. 170, n° 0377-8398, pp. 102066, 01/01/2022)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Toxicity of Environmental and Polystyrene Plastic Particles on the Bivalve Corbicula Fluminea: Focus on the Molecular Responses
Microplastics (MPs) and nanoplastics (NPs) are major ecotoxicological concerns in aquatic environments. Among aquatic organisms, filter feeders are particularly exposed to the ingestion of MPs and NPs, filtering large quantities of water for food and having an unselective feeding strategy. The present study investigates the effect of environmental microplastics (ENV MPs) and nanoplastics (ENV NPs) generated from macro-sized plastic debris collected in the Garonne River (France), and polystyrene NPs (PS NPs) on the freshwater bivalve Corbicula fluminea (Müller 1774). The organisms were exposed to each type of plastic particle at three concentrations: 0.008, 10 and 100 μg L−1 for 21 days. Gene expression measurements were conducted in gills and visceral mass at 7 and 21 days to assess the effects of plastic particles on different functions (endocytosis, detoxication, respiratory chain, oxidative stress, immunity, apoptosis and neurotoxicity). Our results revealed that: i) an up-regulation of genes, mainly involved in endocytosis, oxidative stress, immunity, apoptosis and neurotoxicity, was observed at 7 days of exposure for almost all environmental plastic particles and at 21 days of exposure for PS NPs in the gills, ii) PS NPs at the three concentrations tested and ENV MPs at 0.008 μg L−1 induced strong down-regulation of genes involved in detoxication, oxidative stress, immunity, apoptosis and neurotoxicity at 7 days of exposure in the visceral mass whereas ENV MPs at 10 and 100 μg L−1 and all ENV NPs induced less pronounced effects, iii) overall, PS NPs and ENV MPs 0.008 μg L−1 did not trigger the same effects as ENV MPs 10 and 100 μg L−1 and all ENV NPs, either in the gills or the visceral mass at 7 and 21 days of exposure. This study highlighted the need to use MPs and NPs sampled in the environment for future ecotoxicological studies, compared to manufactured PS NPs as their properties (composition, size distribution, surface charge, additive and adsorbed contaminants) induce different effects at the molecular level to living organisms.
(SSRN Electronic Journal, 01/01/2022)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Source-to-sink pathways of clay minerals in the cadiz contourite system over the last 25 kyrs: The segregational role of mediterranean outflow water
Despite major advances in our understanding of the interactions between bottom currents and sedimentary deposits over the last forty years, few studies have focused on the nature of fine particles in contourite depositional systems (CDS). XRD analyses of marine sediments can be used to improve our understanding of fine-grained sediment sources and settling processes. This work presents a detailed sedimentological study of sediment cores collected over the middle slope of the Gulf of Cadiz as part of Integrated Ocean Drilling Program Expedition 339 and the 2001 CADISAR cruise. We performed high-resolution clay mineral analyses to reconstruct the pathways of fine-grained particles from their sources to their deposition along the contourite depositional system of the Gulf of Cadiz (source-to-sink approach). The clay mineral associations reflect the major contribution of the Guadalquivir River and North African rivers/dusts to fine particles settling over the middle slope. Our
(Marine Geology. vol. 443, n° 0025-3227, pp. 106697, 01/01/2022)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LOG, INSU - CNRS, ULCO, CNRS, IRD [Ile-de-France]
MOW strengthening and contourite development over two analog climate cycles (MIS 12–11 and MIS 2–1) in the Gulf of Cadíz: An impact on North Atlantic climate during deglaciation V and MIS 11?
(Global and Planetary Change. vol. 208, n° 0921-8181, pp. 103721, 01/01/2022)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Primary drivers of multidecadal spatial and temporal patterns of shoreline change derived from optical satellite imagery
Understanding and predicting shoreline change along sandy coasts requires continuous (in both time and space) long-term (decades) shoreline data at good spatial (e.g. 100 s of metres) and temporal (e.g. months) resolution. Publicly available satellite imagery can now provide such time series. However, satellite-derived shorelines (SDS) are associated with uncertainties, particularly at high-energy meso-macrotidal coasts, which challenge the assessment of long-term trends and interannual variability. In this paper we address the 1984–2020 time- and space-evolution of 269 km of high-energy meso-macrotidal sandy coast in southwest France using uncertain (no tide and runup correction) SDS data. The shoreline trends are validated with field data collected over the period 2008–2019. Over 1984–2020, the shoreline eroded by 0.55 m/yr with maximum erosion (accretion) reaching 15.61 m/yr (6.94 m/yr), with the largest changes observed along coasts adjacent to the inlet and estuary mouths. We show that, away from the presence of ebb-tide deltas and swash bars affecting offshore wave transformation and nearshore circulation, the long-term shoreline trend is well explained by the gradients in longshore drift computed from a regional wave hindcast and an empirical longshore transport formula. By averaging the yearly SDS along the entire coastline, we find that interannual shoreline variability is well correlated with the winter West Europe Pressure Anomaly (WEPA), which outscores the other conventional teleconnection pattern indices. WEPA even explains >80 % of the space-averaged shoreline variability over the recent period 2014–2020 when more and higher quality satellite images are available. A more local assessment of the links between climate indices and shoreline response shows that correlation with all climate indices dramatically drops downdrift of the large-scale estuary mouths and inlets. This suggests that along this 10–20 km stretch of downdrift coast, shoreline response is controlled factors internal to the estuary mouth/inlet system. The rest of the coast is mostly controlled by factors external to the system, which are primarily the variability in winter-mean wave height correlated to winter WEPA index. Overall, we demonstrate that an adapted space-averaging of uncorrected (noisy) SDS dataset can allow addressing the time- and space variability of shoreline change and their primary drivers including large-scale climate patterns of atmospheric variability. We also advocate that such SDS analysis can be performed along any coastline in the world in order to guide future model development and application.
(Geomorphology. vol. 413, n° 0169-555X, pp. 108360, 13/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, OCNA, BRGM
Multiple phytoplankton community responses to environmental change in a temperate coastal system: A trait-based approach
The effect of environmental change in structuring the phytoplankton communities of the coastal waters of the Eastern English Channel was investigated by applying a trait-based approach on two decades (1996-2019) of monitoring on diatoms and Phaeocystis . We show that phytoplankton species richness in an unbalanced nutrient supply context was influenced by wind-driven processes, ecological specialization for dissolved inorganic phosphorous, temporal niche differentiation, and a competition-defense and/or a growth-defense trade-off, a coexistence mechanism where weak competitors (i.e., slower growing) are better protected against predation. Under the influence of both environmental perturbations (e.g., wind-driven processes, freshwater influence, unbalanced nutrient levels) and biotic interactions (e.g., competition, predation, facilitation), phytoplankton species exhibited specific survival strategies such as investment on growth, adaptation and tolerance of species to environmental stresses, silicification and resource specialization. These strategies have led to more speciose communities, higher productivity, functional redundancy and stability in the last decade. Our results revealed that the unbalanced nutrient reduction facilitated Phaeocystis blooms and that anthropogenic climate warming and nitrate reduction may threaten the diatom communities of the eastern English Channel in a near future. Our results provide strong support for biogeographical historical and niche-based processes in structuring the phytoplankton community in this temperate region. The variety of species responses that we characterized in this region may help to better understand future changes in pelagic ecosystems, and can serve as a basis to consider functional approaches for future ecosystem management.
(Frontiers in Marine Science. vol. 9, n° 2296-7745, pp. 914475, 13/04/2026)
LOG, INSU - CNRS, ULCO, CNRS, IRD [Ile-de-France], ULCO, BOREA, UNICAEN, NU, MNHN, IRD, SU, CNRS, UA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, TUMSAT, OOB, SU, CNRS, OASU, UB, INSU - CNRS, ULR, CNRS, INRAE, UCA Faculté Médecine, UniCA, MIO, IRD, AMU, INSU - CNRS, UTLN, CNRS, DYNECO, IFREMER
AMOC Recent and Future Trends: A Crucial Role for Oceanic Resolution and Greenland Melting?
The Atlantic Meridional Overturning Circulation (AMOC) is a crucial element of the Earth climate. It is a complex circulation system difficult to monitor and to model. There is considerable debate regarding its evolution over the last century as well as large uncertainty about its fate at the end of this century. We depict here the progress since the IPCC SROCC report, offering an update of its chapter 6.7. We also show new results from a high-resolution ocean model and a CMIP6 model to investigate the impact of Greenland Ice Sheet (GrIS) melting, a key uncertainty for past and future AMOC changes. The ocean-only simulation at 1/24° resolution in the Arctic-North Atlantic Ocean performed over the period 2004–2016 indicates that the spread of the Greenland freshwater runoff toward the center of the Labrador Sea, where oceanic convection occurs, seems larger in this model than in a CMIP6 model. Potential explanations are related to the model spatial resolution and the representation of mesoscale processes, which more realistically transport the freshwater released around the shelves and, through eddies, provides strong lateral exchanges between the fine-scale boundary current and the convective basin in the Labrador Sea. The larger freshening of the Labrador Sea in the high-resolution model then strongly affects deep convection activity. In the simulation including GrIS melting, the AMOC weakens by about 2 Sv after only 13 years, far more strongly than what is found in the CMIP6 model. This difference raises serious concerns on the ability of CMIP6 models to correctly assess the potential impact of GrIS melting on the AMOC changes over the last few decades as well as on its future fate. To gain confidence in the GrIS freshwater impacts on climate simulations and therefore in AMOC projections, urgent progress should be made on the parameterization of mesoscale processes in ocean models.
(Frontiers in Climate. vol. 4, n° 2624-9553, pp. 838310, 13/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LOCEAN-VOG, LOCEAN, MNHN, IRD, INSU - CNRS, SU, CNRS, IPSL (FR_636), ENS-PSL, UVSQ, CEA, INSU - CNRS, X, CNES, SU, CNRS, UPCité, DMI, LOCEAN-NEMO R&D, LOCEAN, MNHN, IRD, INSU - CNRS, SU, CNRS, IPSL (FR_636), ENS-PSL, UVSQ, CEA, INSU - CNRS, X, CNES, SU, CNRS, UPCité
Evaluating seasonal sea-ice cover over the Southern Ocean at the Last Glacial Maximum
Southern hemispheric sea-ice impacts ocean circulation and the carbon exchange between the atmosphere and the ocean. Sea-ice is therefore one of the key processes in past and future climate change and variability. As climate models are the only tool available to project future climate change, it is important to assess their performance against observations for a range of different climate states. The Last Glacial Maximum (LGM, ∼21 000 years ago) represents an interesting target as it is a relatively well-documented period with climatic conditions very different from preindustrial conditions. Here, we analyze the LGM seasonal Southern Ocean sea-ice cover as simulated in numerical simulations as part of the Paleoclimate Modelling Intercomparison Project (PMIP) phases 3 and 4. We compare the model outputs to a recently updated compilation of LGM seasonal Southern Ocean sea-ice cover and summer sea surface temperature (SST) to assess the most likely LGM Southern Ocean state. Simulations and paleo-proxy records suggest a fairly well-constrained glacial winter sea-ice edge between 50.5 and 51° S. However, the spread in simulated glacial summer sea-ice is wide, ranging from almost ice-free conditions to a sea-ice edge reaching 53° S. Combining model outputs and proxy data, we estimate a likely LGM summer sea-ice edge between 61 and 62° S and a mean summer sea-ice extent of 14-15×106 km2, which is ∼20 %-30 % larger than previous estimates. These estimates point to a higher seasonality of southern hemispheric sea-ice during the LGM than today. We also analyze the main processes defining the summer sea-ice edge within each of the models. We find that summer sea-ice cover is mainly defined by thermodynamic effects in some models, while the sea-ice edge is defined by the position of Southern Ocean upwelling in others. For models included in both PMIP3 and PMIP4, this thermodynamic or dynamic control on sea-ice is consistent across both experiments. Finally, we find that the impact of changes in large-scale ocean circulation on summer sea-ice within a single model is smaller than the natural range of summer sea-ice cover across the models considered here. This indicates that care must be taken when using a single model to reconstruct past climate regimes.
(Climate of the Past. vol. 18, n° 1814-9324, pp. 845-862, 13/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Glyphosate-based herbicide exposure: effects on gill microbiota of rainbow trout ( Oncorhynchus mykiss ) and the aquatic bacterial ecosystem
The herbicide glyphosate has been widely used in the past 40 years, under the assumption that side effects were minimal. In recent years, its impact on microbial compositions and potential indirect effects on plant, animal and human health have been strongly suspected. Glyphosate and co-formulates have been detected in various water sources, but our understanding of their potential effects on aquatic animals is still in its infancy compared with mammals. In this study, we investigated the effect of chronic exposure to an environmentally relevant concentration of glyphosate on bacterial communities of rainbow trout (Oncorhynchus mykiss). Gills, gut contents and gut epithelia were then analyzed by metabarcoding targeting the 16S rRNA gene. Our results revealed that rainbow trout has its own bacterial communities that differ from their surrounding habitats and possess microbiomes specific to these three compartments. The glyphosate-based herbicide treatment significantly affected the gill microbiome, with a decrease in diversity. Glyphosate treatments disrupted microbial taxonomic composition and some bacteria seem to be sensitive to this environmental pollutant. Lastly, co-occurrence networks showed that microbial interactions in gills tended to decrease with chemical exposure. These results demonstrate that glyphosate could affect microbiota associated with aquaculture fish.
(FEMS Microbiology Ecology. vol. 98, n° 0168-6496, 13/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ANSES, LM2E, IFREMER, UBO EPE, CNRS