Exploring Future Shoreline and Nearshore Evolution Under Sea-Level Rise Projections: Application of the LX-ST Model to Lacanau
This study applies the reduced-complexity model LX-ST to simulate the future evolution of the shoreline and nearshore morphology of Lacanau, a wave-dominated, erosion-prone coastal site in southwest France. By coupling longshore transport with shoreface translation processes, the model evaluates changes under various IPCC sea-level rise scenarios through 2100. Results highlight significant spatial variability in erosion, with pronounced downdrift retreat near coastal defenses. The findings demonstrate the utility of LX-ST for informing long-term coastal adaptation strategies.
(01/09/2025)
BRGM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
A small increase in temperature could rapidly expand the latitudinal range and pathogenicity of the marine trematode parasite Curtuteria arguinae
The phenology and transmission dynamics of the marine trematode Curtuteria arguinae were investigated, a parasite whose recently elucidated life cycle involves oystercatchers (Haematopus ostralegus), needle snails (Bittium reticulatum), and edible cockles (Cerastoderma edule). To assess the influence of temperature and light on cercarial emergence, infected B. reticulatum were exposed to temperatures ranging from 15 °C to 27 °C under both light and dark conditions. Cercarial emergence peaked under warm and illuminated conditions, showing strong temperature dependence, and, to a lesser extent, light dependence. Emergence occurred significantly at temperatures ≥21 °C, with median emergence rates of 12–47 cercariae.day−1, and the positive influence of light was overruled at higher temperatures. A 22-year dataset from Arcachon Bay (France) was also analyzed to determine the timing of first infections in cockles relative to sea and air temperatures, as well as cockle shell size, across ten cohorts. First infections of cockles were consistently observed in late summer, with a mean sea temperature of 20.8 °C, placing cercarial transmission once a thermal threshold is reached. This thermal dependency explains the parasite's current southern distribution. With climate warming, its range is likely to expand northward along the northeastern Atlantic coast, in areas where all hosts are already present. Expansion may also be supported by the northward extension of B. reticulatum. In areas where the parasite is already established, rising temperatures may enhance cercarial output and infection intensity, increasing pathogenic effects on both intermediate hosts and posing a growing threat to ecosystem functioning and cockle fisheries.
(Estuarine, Coastal and Shelf Science. vol. 326, n° 0272-7714, pp. 109541, 01/09/2025)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, OASU, UB, INSU - CNRS, ULR, CNRS, INRAE, SU, SBR, SU, CNRS, ECOMAP, AD2M, SU, CNRS, SBR, SU, CNRS
Radiolarian and Phaeodarian high-rank assemblage change through time in the Scotia Sea: A paleo-genomics approach (IODP Exp. 382)
Radiolaria and Phaeodaria are single-celled eukaryotic zooplankton that inhabit diverse marine environments. While the sedimentary fossil record reveals their ancient origins and morphological diversity, recent advancements in metagenomics and sedimentary ancient DNA (sedaDNA) techniques have highlighted the significant contributions of rarely preserved taxa (e.g., those that are only lightly silicified or soft-bodied) to marine biodiversity and the carbon cycle. Using a paleo-genomic approach, we produced a sedaDNA-based time series of the Radiolarian and Phaeodarian community from the Scotia Sea covering the last 500 kyr. We compared the use of two reference databases, one Radiolarian-and Phaeodarian-specific (RPD) and one more comprehensive eukaryote database (PR 2 ), to assess the validity of a small, taxa-specific database. We determined that the two databases produced comparable results, showing that the overall assemblage changes at the glacial-interglacial scale were similar. At the Class level, Radiolarian and Phaeodarian assemblages appear to have experienced compositional changes during termination events and warm Interglacial periods. This study produced the first Radiolarian-and Phaeodarian-specific reference database. We showed that the Class-level changes that occurred over the last 500 kyr were associated with glacial-interglacial (G-I) cycles, and no permanent shifts away from the natural variation associated with the G-I cycles were found.
(Marine Micropaleontology. vol. 200, n° 0377-8398, pp. 102500, 01/09/2025)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UTAS, UTAS, LOG, INSU - CNRS, ULCO, CNRS, IRD [Ile-de-France], ULCO, UNIBE, ANU
Effect of H2-rich water percolation in porous limestone core: simulation of a leakage in a shallow carbonate freshwater aquifer
Underground Hydrogen Storage (UHS) builds on existing underground storage technologies used for town gas and CO 2 and involves storing hydrogen in various geological structures underground. However, some questions remain regarding this storage method, particularly concerning safety: an untight UHS site could lead to a hydrogen leak to the surface, where the gas could be intercepted by an overlying freshwater aquifer. H 2 would dissolve in the water, and this fluid could react with the surrounding rock. This study investigates the effects of hydrogen-saturated water flow through carbonate rock cores to simulate such an H 2 leakage in a near subsurface freshwater aquifer. Core flooding experiments were conducted on two carbonate facies, a grainstone and a boundstone, using a Hassler cell. Petrophysical and geochemical changes were monitored throughout the experiments. Results indicate that hydrogen remains largely non-reactive in its dissolved form when in contact with calcite. However, the water flow itself induces mechanical pore clogging, leading to significant permeability reduction without affecting the total porosity. A slight calcite precipitation within the pore network is also suggested. Additionally, a loss of dissolved H 2 is observed, likely due to fluid degassing rather than chemical consumption. These findings highlight the importance of considering mechanical processes in UHS scenarios and emphasize the need for further research on the long-term behavior of hydrogen saturated water in carbonate freshwater aquifers.
(International Journal of Hydrogen Energy. vol. 171, n° 0360-3199, 01/09/2025)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Upstream moisture sources and circulation patterns controls Asian monsoon hydroclimate over the past 20,000 years
Speleothem oxygen isotope records (δ18O) from caves in the Asian monsoon region have been widely utilized to reconstruct paleo-monsoon variability. However, interpreting these records remains challenging due to conflicting hypotheses about their relationship with Asian Summer Monsoon (ASM) strength and regional rainfall patterns. In this study, we analyzed 15 cave stalagmite δ18O records collected across East and South Asia, covering the last 20,000 years. Our analysis focuses on key climatic events, including Heinrich Stadial 1 (HS1), the Bølling-Allerød warm period (BA), and the Younger Dryas (YD), to explore the driving force of Asian summer monsoons from both high-latitude North Atlantic climate and lower-latitudes atmospheric circulation patterns. The results revealed that speleothem δ18O variations were predominantly influenced by shifts in upstream moisture sources, particularly from low-latitude regions in the Indian and Pacific Oceans, as evidenced by both observational data and model simulations. We demonstrated that δ18O records from Chinese caves reflect not only local rainfall dynamics but also broader influences from upstream moisture sources.
(Quaternary Science Reviews. vol. 363, n° 0277-3791, pp. 109438, 01/09/2025)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UCLouvain, UMR ISPA, Bordeaux Sciences Agro, INRAE, CAGS, MLR
Comparison of sedimentary ancient DNA (sedaDNA) extraction and shotgun metagenomic library preparation techniques
Sedimentary ancient DNA (sedaDNA) is an emerging field, increasingly being applied to the study of past aquatic ecosystems. However, several sedaDNA extraction methods from deep-ocean sediment matrices and sequencing library preparation have recently been developed, which may complexify results comparison and interpretations. We present a sedaDNA interlaboratory comparison study to assess the impact of extraction and library preparation protocols on metagenomic results. We applied three extraction protocols to four samples from two sediment cores from the Northern Antarctic Peninsula: (1) a ‘combined’ protocol using ethylenediaminetetraacetic acid (EDTA) and silica-in-solution to isolate DNA, (2) a high-guanidine protocol involving long cold centrifugation to remove polymerase chain reaction (PCR) inhibitors, and (3) a commercial kit, the DNeasy PowerSoil Pro Kit. We also compared two library preparation protocols, both optimised versions from Meyer and Kircher (2010). Using a blind approach relying on k-mer similarity assessment, greater variability was observed between individual samples than between protocols. An in-depth analysis of eukaryotic and (highly abundant) diatom community composition revealed that all protocols recovered eukaryotic sedaDNA, with minor differences between extraction and library protocols on sequence composition. However, the different DNA extraction and library preparations influenced the DNA read length, potentially resulting in selective targeting of organisms with variable sedaDNA preservation. This study highlights the importance of selection and standardisation of protocols to ensure reproducibility and comparability of past ecosystem reconstructions, particularly at lower taxonomic levels, e.g. diatoms. Although complete standardisation across research projects is challenging, this study shows that data remain reasonably comparable when processed consistently.
(Marine Micropaleontology. vol. 200, n° 0377-8398, pp. 102498, 01/09/2025)
IBENS, IBENS, ENS-PSL, PSL, INSERM, CNRS, INSERM, CNRS, GOSEE, UPVD, EPHE, PSL, AMU, CEA, UEVE, UTLN, INSERM, SU, CNRS, IRD [Ile-de-France], ENS Paris Saclay, EMBL, Nantes Univ - ECN, Nantes Univ, IMAS, UTAS, EA 7206, MNHN, CNRS, Bordeaux INP, IACT, CSIC, UGR, AWI, MARUM, IGME, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, EPHE, PSL
Lower competition in grasslands and higher facilitation in forests as potential drivers of the higher species richness of calcareous than siliceous communities
We tested the hypothesis that, in calcareous and siliceous ecosystems from the wet temperate climate of southwest France, competition primarily explains differences in community composition and species richness in grasslands but that facilitation is more determinant in forests. In a first experiment, we transplanted, in dry and wet years, grass species of contrasting light requirements in gaps and forest understories to compare on the two bedrocks the effects of herbaceous neighbors in gaps to the effects of adult trees on understory species. In a second experiment, we manipulated light and soil nutrient fertility in the same system and transplanted six understory species to disentangle the direct drivers of the positive effect of trees for understory species. In the first experiment, competition was higher in gaps of siliceous than calcareous bedrocks during wet years and facilitation by canopy trees was higher on calcareous than siliceous bedrocks during dry years. In addition, facilitation in calcareous forests was very intense for species from the shadiest origins, while competition was only significant for species from the sunniest origins. In the second, experiment we found that both higher microclimates buffering ability of forest canopies and higher soil fertility explained the higher facilitation found in calcareous forests. Synthesis: the higher importance of competition in grasslands and facilitation in forests is mostly due to the contrasting adaptations to light conditions of grassland and understory species. The higher facilitation in calcareous forests appeared to be due to higher buffering effect of tree canopies and higher soil fertility in calcareous than siliceous soils. The major role of facilitation in forest communities from favorable conditions has been strongly overlooked in the literature, although it might explain the higher species richness of calcareous than siliceous forests.
(Oikos. vol. 2025, n° 0030-1299, 01/09/2025)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Relationship between REE signatures and biological traits of marine benthic fauna in a temperate mud patch: Application of multivariate analyses
The increasing contamination of coastal environments by Rare Earth Elements (REEs) necessitates a thorough understanding of the dynamics of these elements in ecosystems under anthropogenic pressure. Sedimentary bodies influenced by large rivers, such as the West Gironde Mud Patch (WGMP), are among these pressured ecosystems. REE analyses in seven benthic marine species and ambient media (i.e., dissolved fraction of bottom water, sediments) of this mud patch has provided REE signatures (i.e., REE concentrations and shape of normalized patterns) using one concentration descriptor (i.e., ∑ REE) and six descriptors of pattern shapes (i.e., La/La*; Ce/Ce*; Eu/Eu*; Pr/Lu; Pr/Gd; Gd/Lu). A robust procedure of multivariate analyses (i.e., PERMDISP, PERMANOVAs, PCO) was applied to study the controlling factors of REE signatures in these species.
Assessment of the within-and between-species variability suggests that differences in REE concentrations and shapes of normalized patterns between species were related to the ambient media's geochemical processes and the fauna's ecological and biological traits. REE concentrations in the fauna document trophic dilution, reflected by elevated concentrations in pure microphages and reduced concentrations in pure carnivores. The predominance of calcareous skeletons in bivalves and brittle stars results in a dilution effect on REE concentrations at the whole-organism level. The chitinous exoskeleton of crabs and shrimps is subject to adsorption processes for REEs present in the sediment.
(Marine Pollution Bulletin. vol. 222, n° 0025-326X, 31/08/2025)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CNRS, Bordeaux INP, L3I, ULR, UB, OASU, UB, INSU - CNRS, ULR, CNRS, INRAE
Changes in the Strength of Associations Between Tree Seedlings and Understory Shrubs Along a Regional Drought Gradient in Lebanese Coniferous Forests
ABSTRACT Aims Do the effects of an understory shrub on woody seedlings explain the distributions of relict conifer trees at a regional scale? Location Three natural Cedrus libani reserves from Lebanon. Methods Using an observational approach, we quantified associations of recruits of woody species at the center and periphery of the spiny shrub Juniperus oxycedrus in forests and gaps along a north–south climatic gradient of both winter rainfall continentality and summer drought. We quantified the associations of woody seedlings with shrubs using the Relative Interactions Index (RII) calculated for recruits of all species together (community scale) and for four groups of functionally different species. We then analyzed the variation of RIIs along different treatments. Vapor Pressure Deficit (VPD) was quantified in each treatment combination, and its relationship with species‐group RIIs and abundance was evaluated. Results At the community‐scale, shrubs showed likely higher negative effects on woody seedlings at their center than at their periphery. In contrast, there were contrasting responses at the species‐group level, with overall negative associations for Cedrus , positive associations for a group including Abies cilicica , and intermediate responses for two other groups. Positive associations strongly varied along the drought gradient and with the canopy treatment, while negative associations only slightly increased from forests to gaps. Positive associations varied together with VPD, peaking at an intermediate position along the drought gradient coinciding with the southernmost limit of Abies and declining at the dry extreme of the gradient where Cedrus is still present. Main Conclusions VPD appeared as a crucial driver of tree species occurrence and likely facilitation. Although manipulative experiments are needed to confirm the real occurrence of facilitative and competitive effects of the shrub, our study highlights the potential role of facilitation in explaining tree species distribution at regional scales.
(Journal of Vegetation Science. vol. 36, n° 1100-9233, 04/08/2025)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Contrasting Scenarios for Upper Ocean Temperature Changes at the Last Glacial Maximum Inferred From Inorganic and Organic Paleothermometers: A Case Study From the Eastern Tropical Indian Ocean
Reconstructing paleo seawater temperatures is essential for understanding past climate changes, yet different paleotemperature proxies can yield divergent signals with opposing climatic interpretations. This study reconstructs the upper ocean thermal structure in the eastern tropical Indian Ocean offshore southwest Sumatra across two 2‐kyr periods during the Last Glacial Maximum (LGM, 19–21 ka) and the Late Holocene (LH, 0–2 ka). Our multiproxy approach combines updated, published results from organic paleothermometers (, TEX 86 ), published and newly generated Mg/Ca data from four species of surface and thermocline dwelling planktic foraminifera, alongside new data from clumped isotope analysis (Δ 47 ) on the same foraminiferal species. The new Δ 47 data suggest surface dwellers experienced more pronounced cooling (6.1°C; 95% confidence interval 4.7–7.5°C) than the thermocline dwellers (1.6°C; 1.1–2.1°C) during the LGM compared to the LH, resulting in a weaker LGM vertical temperature gradient in the upper ocean and a deeper thermocline. While this weaker thermal gradient is generally consistent with previous Mg/Ca reconstructions, our new Δ 47 data for the LH suggest a higher thermocline temperature than the Mg/Ca‐based data, which may have been affected by dissolution effects as indicated by the correlation between Mg/Ca values and shell weights of thermocline dwellers. In contrast, paired and TEX 86 suggest a stronger or similar upper ocean thermal gradient during the LGM. Based on our analysis of modern data, we propose that the apparent discrepancy between the foraminiferal and biomarker approaches might have stemmed from proxies reflecting different depths with different sensitivities to upwelling dynamics.
(Paleoceanography and Paleoclimatology. vol. 40, n° 2572-4525, 04/08/2025)
NTU, NTOU, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, BCCR, BIO / UiB, UiB, NTU, NTU