Variations in the morphometric characteristics of Fragilariopsis kerguelensis in the Southwest Pacific sector of the Southern Ocean over the past 40,000 years
High-throughput measurements demonstrated the presence of two morphotypes of Fragilariopsis kerguelensis in the Atlantic sector of the Southern Ocean, the proportions of which in downcore samples may be used to reconstruct past sea-surface temperatures quantitatively. We here measured the mean length, width, area, and rectangularity in core SO136-111 to assess variations in both morphotypes in the Polar Front Zone of the western Pacific sector of the Southern Ocean over the past 40,000 years. Mean length, width, and area increased rapidly at the end of the glacial period when the Polar Front migrated southward to reach the core site, ocean temperature increased, and sea ice was no longer present. In contrast, mean rectangularity decreased at the end of the glacial period, when the proportion of the cold-water, high-rectangularity morphotype declined as the ocean warmed at the core site. Downcore patterns and quantitative values of all morphometric characteristics in the southwest Pacific sector agree well with previous studies from the Atlantic sector, suggesting the presence of a similar population of F. kerguelensis in the open Southern Ocean. Nevertheless, rectangularity-based relationships can ultimately produce unrealistic estimates of sea-surface temperatures in core SO136-111 when the proportion of the high-rectangularity morphotype is too low, indicating that these approaches are now limited to temperatures below 3-4°C.
(Marine Micropaleontology. vol. 195, n° 0377-8398, pp. 102447, 01/03/2025)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Bivalve monitoring over French coasts: multi-decadal records of carbon and nitrogen elemental and isotopic ratios (δ13C, δ15N and C:N) as ecological indicators of global change
Recent changes in climate and environment, influenced by both global and local factors, have had profound impacts on coastal ecosystem functioning and trajectories. By examining archived samples from ongoing ecological monitoring efforts, particularly focusing on bivalves like mussels and oysters, we gain a valuable long-term perspective on how ecosystems are responding at various scales. We conducted analyses on carbon and nitrogen elemental and isotopic ratios (C:N, δ13C, δ15N) of mussel and oyster soft tissues collected annually at 33 sites along the French coast from 1981 to 2021. This extensive dataset (https://doi.org/10.17882/100583, Liénart et al., 2024a) offers a comprehensive view spanning multiple decades and ecosystems, allowing to track how coastal ecosystems and marine species record changing climate, physical-chemical environments and organic matter cycles. Additionally, these data are crucial for establishing isotope baselines for studying food webs. Ultimately, this data set provide valuable information for more effective ecosystem conservation and management strategies in our rapidly changing world.
(Earth System Science Data. vol. 17, n° 1866-3508, pp. 799-815, 01/03/2025)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, FTMC, CCEM, IFREMER, DYNECO, IFREMER, BOREA, MNHN, IRD, SU, CNRS, UA
A new species of the Thelepus cincinnatus complex from Saint-Pierre and Miquelon Archipelago (NW Atlantic) and genetic diversity of Amphitrite figulus (Dalyell, 1853) (Annelida, Terebelliformia)
During an ecological survey conducted in 2023 around the coastal waters of Saint-Pierre and Miquelon Archipelago, a sub-Arctic archipelago located about 20 km south of Newfoundland (NW Atlantic), two species of Terebelliformia were sampled. The first one is Amphitrite figulus (Dalyell, 1853) a species described from Europe but with a wide distribution across the Northern Atlantic Ocean. The second one, Thelepus recheri n. sp., is a new species characterised by the presence of a wide dorsal branchial gap and the presence of notopodia almost until the end of the body. Molecular studies were performed and two markers were sequenced and analyzed, COI and 16S. These genetic data revealed that (1) Thelepus recheri n. sp. belongs to the T. cincinnatus complex and (2) a clear population structure within A. figulus, with two populations on each side of the Atlantic separated from each other. However, our data are inconclusive in resolving whether these two clusters are two populations within the same species or two distinct species.
(Zootaxa. vol. 5588, n° 1175-5326, pp. 250-268, 14/02/2025)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEMAR, IRD, IFREMER, UBO EPE, CNRS, IUEM, IRD, INSU - CNRS, UBO EPE, CNRS, UMS POREA, INSU - CNRS, CNRS, INRAE, UIB
Devenir des PFAS dans un sol structuré : rôle des particules colloïdales et macropores
Les mousses anti-incendie contiennent un mélange de substances per- et polyfluoroalkylées (PFAS). Celles-ci sont persistantes dans l’environnement, et les sites d'entraînement des pompiers constituent une source de contamination pour les sols, leur biota et les eaux souterraines. Le devenir des PFAS dans les sols a été principalement étudié en utilisant des situations expérimentales modèles : sols recompactés, souvent saturés, et contaminés artificiellement avec quelques molécules. Nous avons étudié pour la première fois le devenir des PFAS dans un sol structuré en soumettant des colonnes de sol non perturbé, prélevées sur un ancien site d’entrainement des pompiers, à une série de pluies simulées. Ces expériences ont montré que (i) lorsque la longueur de la chaîne perfluorée nc était ≤ 7, la diffusion était le mécanisme limitant le transport, (ii) les particules colloïdales facilitaient la mobilité de certains fluoro-télomères et acides perfluorés avec n≥8, (iii) les conditions hydrodynamiques, liées à la structure du sol, déterminaient l’étendue du transport en phase colloïdale des PFAS. Ces résultats ont permis de préciser le modèle conceptuel du devenir des PFAS dans le sol et de proposer les mécanismes qu’il conviendrait d’étudier pour l’améliorer.
(04/02/2025)
EMMAH, AU, INRAE, GERS-LEE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Long-term impact of dredging and beach nourishment works on benthic communities
Dredging and rainbowing techniques are commonly used to replenish sandy beaches and protect the coast against erosion. Since 2003, such operations have been conducted every other year on Pyla Beach, Arcachon Bay (French Atlantic Coast). The evolution of macrobenthic communities subjected to regular disturbance was analyzed once in springtime at dredging and disposal sites, as well as in a control area, over 21 years. The overall benthic community was dominated by the same few species. The dredged area harbors a benthic community whose characteristics suggest the maintenance of a disturbed status, compared to the control area, whose community follows a trajectory possibly influenced by the general decrease of organic matter in the sediment. Regarding the disposal site, species richness is slowly declining. In both disturbed areas, the community was dominated by species able to recolonize rapidly (polychaetes, peracarid crustaceans), while the control area rather favored bivalves.
(Estuarine, Coastal and Shelf Science. vol. 313, n° 0272-7714, pp. 109119, 01/02/2025)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Is reducing phosphorus inputs sufficient to reduce hypoxia in estuaries? The example of the Loire estuary
Coastal deoxygenation is mainly attributed to excessive nutrient and organic matter inputs from anthropogenic activities. However, although mitigation strategies have been implemented to reduce nutrient inputs, the recovery of estuarine systems has often been limited. By examining long-term data from the turbid Loire estuary, which is prone to summer hypoxia, we aimed to understand the influence of these initiatives on nutrient and dissolved oxygen levels. The data showed that despite the reduction of dissolved phosphorus in the inner estuary, summer hypoxia persisted. By integrating high spatial resolution datasets, we identified nutrient sources, particularly ammonium, in the estuarine turbidity maximum zone. Nutrient recycling is likely to maintain summer hypoxia and hinder ecosystem recovery from hypoxia. A comprehensive understanding of estuarine geochemistry and internal nutrient cycling is essential to develop targeted remediation strategies and mitigate the ongoing threat of hypoxia.
(Estuarine, Coastal and Shelf Science. vol. 313, n° 0272-7714, pp. 109110, 01/02/2025)
LPG, UM, UA, INSU - CNRS, CNRS, Nantes univ - UFR ST, Nantes Univ, Bordeaux INP, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IPREM, UPPA, INC-CNRS, CNRS, LPG-ANGERS, LPG, UM, UA, INSU - CNRS, CNRS, Nantes univ - UFR ST
Source of rainfall above Mediterranean caves (Chauvet and Orgnac) and long-term trend of cave dripping oxygen isotopes based on 20 years monitoring records: Importance for speleothem-based climate reconstructions
(Quaternary Science Reviews. vol. 349, n° 0277-3791, pp. 109145, 01/02/2025)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, GLACCIOS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, GEOTRAC, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA
Distribution of organic matter and diatom frustules (diversity, flux) along the western Indian continental shelf related to contrasting physicochemical settings
The western Indian continental shelf (eastern Arabian Sea) exhibits contrasting biogeochemical features. This area becomes highly productive due to summer monsoon-driven coastal upwelling in the south and winter monsoon-induced convective mixing in the north. Additionally, in the northern self, the eastern boundary of the Oxygen Minimum Zone (OMZ) persists but is absent in the south. Phytoplankton blooms are dominated by diatoms that contribute to sedimentary phytodetritus flux supplying major elements (C, N, Si) and food for benthic biota and hence important to address. Here we present the data on organic matter content, diatom frustule flux, abundance, and diversity using surface sediments (core tops collected using a multicorer) from 6 locations (11-21° N) along the shelf in a 2° interval at 200 m isobaths. The organic matter retrieved from the core top was relatively fresh (nearly 4.5 years old) as evident from 210 Pb profiles Frustule abundance and diversity (the maximum at 15° N and minimum at 19° N) varied from 0.10-18.46 ×10 4 valves g -1 and 0.79-2.32, respectively. A total of 36 diatom genera were found with two centric (Thalassiosira and Coscinodiscus), and one pennate (Nitzschia) diatoms as major contributors. The higher contribution of Thalassiosira was observed throughout the shelf dominating the south (11, 13, 15° N), whereas, in the north (17, 19, 21° N) Coscinodiscus was dominant.
The highest organic matter content (3.4%) and frustule abundance (18.46 × 10 4 valves g -1 ) were seen at 15° N despite low diatom valve flux (3.3 × 10 3 valves cm -2 yr -1 ) and could be due to the influence of OMZ, where organic matter is well preserved. Contrarily, the upwelling-influenced station in the south (at 11° N) exhibited the highest diatom valve flux (10.14 × 10 3 valves cm -2 yr -1 ) however low organic matter content (1.6 %) and frustule abundance (4.99×10 4 valves g -1 ) was attributed to faster mineralization. This study suggested that the preservation potential of organic matter varies across the shelf and is likely to control its recycling, impacting nutrient release and resources for the benthic community.
(Marine Environmental Research. vol. 204, n° 0141-1136, pp. 106940, 01/02/2025)
NIO, AcSIR, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Correction to: Main conclusions and perspectives from the collective scientific assessment of the effects of plant protection products on biodiversity and ecosystem services along the land–sea continuum in France and French overseas territories
The default Competing Interests statement has been published when in fact the following information is missing: Since 2022, Stéphane Pesce has held the position of Vice-Chairman of the evertéa Foundation, which since 2013 has been chaired by Philippe Garrigues, Editor-in-Chief of Environmental Science and Pollution Research. These Vice-Chairman and Chairmanship functions are performed on a purely voluntary basis, with no compensation of any kind. Stéphane Pesce co-authored this article as part of his role as scientific lead for the collective scientific assessment on the effects of plant protection products on biodiversity and ecosystem services along the land–sea continuum in France and French overseas territories, on which this work is based. The other authors declare no competing interests.
(Environmental Science and Pollution Research. vol. 32, n° 0944-1344, pp. 4927-4928, 31/01/2025)
RiverLy, INRAE, ECOSYS, INRAE, IFREMER, INRAE, UCA, LPED, IRD, AMU, INERIS, EMMAH, AU, INRAE, ICE, VAS, CRIOBE, UPVD, EPHE, PSL, CNRS, URCA, CNELIAS, AU, AMU, MMSH, AMU, CNRS, CNRS, UCBL, LCE, CNRS, UMLP, UBFC, UMR SAVE, UB, Bordeaux Sciences Agro, INRAE, DECOD, IFREMER, INRAE, Institut Agro, Institut Agro, OFB - DRAS, OFB, UniCA, ENSFEA, LEREPS, UT Capitole, Comue de Toulouse, UT2J, Comue de Toulouse, ENSFEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UMR Eco&Sols, Cirad, IRD, INRAE, Institut Agro, IODE, UR, CNRS, UPR HORTSYS, Cirad, UMR MARBEC, IRD, IFREMER, CNRS, UM, INRAE, Institut Agro, UBE, AMURE, IRD, IFREMER, UBO EPE, CNRS, UR EABX, INRAE, AU, ICRA, UdG, PHYTOX, IFREMER, URAFPA, UL, INRAE, UR HYCAR, INRAE
Impact of land cover and climate change on Aquifer Thermal and Energy Storage (ATES) system performance
This study investigates the impact of climate change and intense urbanization on Low-Temperature Aquifer Thermal Energy Storage (LT-ATES) systems. A synthetic groundwater model was developed to consider transient thermal boundary conditions due to climate change, urbanization, and evolving building thermal demands. Four scenarios were analyzed, showing potentially significant influences on subsurface thermal conditions, leading to distinct aquifer temperature profiles. The results for conditions with strong ground heat gain indicate pronounced subsurface warming and imbalanced thermal plume extensions and decreasing ATES performance over time. Recommendations include incorporating realistic surface boundary conditions in ATES modeling and strategies to mitigate adverse thermal impacts from urbanization.
(Geothermics. vol. 127, n° 0375-6505, 30/01/2025)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UMR G-EAU, Cirad, BRGM, IRD, INRAE, Institut Agro, UM, MLU