Study of the dissolved organic matter (DOM) of the Auzon cut-off meander (Allier River, France) by spectral and photoreactivity approaches
Wetlands are recognized for the importance of their hydrological function and biodiversity, and there is now a consensus to protect and restore them as well as to complete the knowledge on their functioning. Here, we studied the dissolved organic matter (DOM) of a wetland composed of the Auzon cutoff meander, the Allier River, the alluvial fluvial flow, and watershed aquifer. Water was sampled at different locations, in spring, summer, and autumn. For each sample, DOM was characterized for its chemical and optical properties and its photooxidant capacity through its ability to generate DOM triplet excited states (3 DOM*) and singlet oxygen upon simulated solar light exposure. UV-visible and fluorescence indices revealed that DOM was mainly microbial-derived whatever the sampling sites with spatial and temporal variations in terms of aromaticity (5.5-22%), specific UV absorbance at 254 nm (0.28-2.82 L m −1 mgC −1), ratio of the absorbance at 254 and 365 nm (4.6-10.8), fluorescence index (1.35-166), and biological index (0.812-2.25). All the samples generated 3 DOM* and singlet oxygen, rates of formation of which showed parallel variations. Using principal component analysis (PCA), we found positive correlations between the sensitizing properties of DOM samples and parameters associated to the abundance of low molecular weight and low absorbing chromophores. Moreover, the parameter variation across the wetland reinforced the hydrological movements observed in a previous study, suggesting that these parameters could be used as water connection tracers.
(Environmental Science and Pollution Research. vol. 27, n° 0944-1344, pp. 26385-26394, 26/04/2026)
ICCF, SIGMA Clermont, INC-CNRS, UCA [2017-2020], CNRS, GEOLAB, UBP, IR SHS UNILIM, UNILIM, UCA [2017-2020], CNRS, UCA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Foraminiferal community response to seasonal anoxia in Lake Grevelingen (the Netherlands)
Over the last decades, hypoxia in marine coastal environments has become more and more widespread, prolonged and intense. Hypoxic events have large consequences for the functioning of benthic ecosystems. In severe cases, they may lead to complete anoxia and the presence of toxic sulfides in the sediment and bottom-water, thereby strongly affecting biological compartments of benthic marine ecosystems. Within these ecosystems, benthic foraminifera show a high diversity of ecological responses, with a wide range of adaptive life strategies. Some species are particularly resistant to hypoxia-anoxia, and consequently it is interesting to study the whole foraminiferal community as well as species-specific responses to such events. Here we investigated the temporal dynamics of living benthic foraminiferal communities (recognised by CellTracker™ Green) at two sites in the saltwater Lake Grevelingen in the Netherlands. These sites are subject to seasonal anoxia with different durations and are characterised by the presence of free sulfide (H 2 S) in the uppermost part of the sediment. Our results indicate that foraminiferal communities are impacted by the presence of H 2 S in their habitat, with a stronger response in the case of longer exposure times. At the deepest site (34 m), in summer 2012, 1 to 2 months of anoxia and free H 2 S in the surface sediment resulted in an almost complete disappearance of the foraminiferal community. Conversely, at the shallower site (23 m), where the duration of anoxia and free H 2 S was shorter (1 month or less), a dense foraminiferal community was found throughout the year except for a short period after the stressful event. Interestingly, at both sites, the foraminiferal community showed a delayed response to the onset of anoxia and free H 2 S, suggesting that the combination of anoxia and free H 2 S does not lead to increased mortality , but rather to strongly decreased reproduction rates. At the deepest site, where highly stressful conditions prevailed for 1 to 2 months, the recovery time of the community takes about half a year. In Lake Grevelingen, Elphidium selseyense and Elphidium magellanicum are much less affected by anoxia and free H 2 S than Ammonia sp. T6. We hypothesise that this is not due to a higher tolerance for H 2 S, but rather related to the seasonal availability of food sources, which could have been less suitable for Ammonia sp. T6 than for the elphidiids.
(Biogeosciences. vol. 17, n° 1726-4170, pp. 1415-1435, 26/04/2026)
LPG-ANGERS, LPG, UA, UN UFR ST, UN, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LPG, UA, UN UFR ST, UN, INSU - CNRS, CNRS, NIOZ
Lidar Observations of the Swash Zone of a Low-Tide Terraced Tropical Beach under Variable Wave Conditions: The Nha Trang (Vietnam) COASTVAR Experiment
(Journal of Marine Science and Engineering, 26/04/2026)
LEGOS, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LGO, UBS, IFREMER, UBO EPE, CNRS, LEESA, UB, CNRS, HCMUT, VNU-HCM, LGL-TPE, ENS de Lyon, UCBL, INSU - CNRS, UJM, CNRS
Contrasting responses of different functional groups stabilize community responses to a dominant shrub under global change
Changes in precipitation regimes and nitrogen deposition levels due to global change are altering terrestrial ecosystems worldwide. Most attempts at understanding how biotic interactions affect plant species and community responses to global change have focused on biotic interactions measured at the community level. However, these approaches ignore that communities include functionally dissimilar species that might respond differently to changes in the effects of dominant neighbours along environmental gradients. We test the hypothesis that plant species with differences in functional traits may exhibit contrasting interactions with a dominant shrub species within a single community, thereby stabilizing community-level responses to the effects of global change. We manipulated water and nitrogen applications in a semi-arid dune community in northern China, quantified the biomass of herbaceous species occurring below the dominant shrub, Artemisia ordosica, and in adjacent open patches (without the shrub), and measured herbaceous species height and leaf dry matter content. The effects of A. ordosica were quantified at the species, group and community levels using the relative interaction index (RII). Redundancy analysis was performed on species traits and the RII values to assess the relationships between functional differences in species and plant–plant interactions. Species were then grouped using a cluster analysis and the RII values were recalculated at the group level. The redundancy analysis showed that species height and leaf dry matter content were significantly correlated to the changes in species' responses to the effect of A. ordosica along treatments. The four groups of species identified by the cluster analysis showed contrasting variations in competitive or facilitative responses depending on species traits and environmental treatments. However, the interactions measured at the group level balanced the community-level responses, as we found no significant changes in the effects of A. ordosica along treatments for community biomass, richness and functional diversity indices. Synthesis. Our findings indicate that species with different functional strategies within a community exhibit contrasting responses to a dominant shrub along environmental gradients. These contrasting changes in plant–plant interactions of functionally different species may balance the responses of community-level metrics. This suggests that functional differences between species groups and the balance of plant–plant interactions stabilize community responses to global change. © 2021 British Ecological Society
(Journal of Ecology. vol. 109, n° 0022-0477, pp. 1676-1689, 26/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Does parasitism influence sediment stability? Evaluation of trait-mediated effects of the trematode Bucephalus minimus on the key role of cockles Cerastoderma edule in sediment erosion dynamics
In coastal environments, bioturbators greatly influence the physical and biogeochemical properties of sediments with consequences for central ecological processes such as erosion dynamics. In addition to their direct impact on sediment stability, bioturbators can have an impact on sediment erosion processes by modulating the growth of microphytobenthic organisms that stabilise the surface layer of sediments. The direct and indirect influences of bioturbators on sediment dynamics depend on the magnitude of their activity and inherently on their physiological state. Bioturbators are infected by various parasites, which have a substantial impact on their physiology and behaviour. However, the knock-on effects of parasites on key ecosystem functions like sediment dynamics remain poorly studied. We conducted flume experiments to investigate the indirect influence of the trematode Bucephalus minimus parasitising the common cockle Cerastoderma edule on the dynamics of sandy sediments enriched or not with microphytobenthos (MPB). Cockles modified bed roughness, sediment surface erodibility and hence destabilised sandy sediments. In sediments not enriched with MPB, both unparasitised and parasitised organisms had a similar impact on the stability of sandy sediments. In contrast, parasitism slightly reduced the destabilisation effect of cockles in MPB-enriched sediments. In the latter, parasitised cockles did not interfere with MPB growth whereas unparasitised organisms constrained the microalgae development. However, the enrichment of the surface layers of sandy sediments with MPB did not modulate the erosion dynamics of these environments. Thus, the lower destabilisation effect of parasitised cockles was not here linked to a stabilisation effect of MPB. When standardised for length, parasitised cockles were lighter than unparasitised organisms. Weakened cockles may have had a lower bioturbation potential than unparasitised conspecifics. If so, the influence parasitised cockles had on sediment erodibility and sediment roughness may have been reduced. The absence of a parasitism effect on the dynamics of MPB-unenriched sediments remains nonetheless unclear.
(Science of the Total Environment. vol. 733, n° 0048-9697, pp. 139307, 26/04/2026)
BOREA, UNICAEN, NU, MNHN, IRD, SU, CNRS, UA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CHRU Besançon
Estrogenic activity of surface waters using zebrafish- and human-based in vitro assays : The Danube as a case-study
Most in vitro reporter gene assays used to assess estrogenic contamination are based on human estrogen receptor α (hERα) activation. However, fish bioassays can have distinct response to estrogenic chemicals and mixtures, questioning the relevance of human-based bioassays for assessing risk to this species. In this study, zebrafish liver cells stably expressing zebrafish ERβ2 (ZELHβ2) and human breast cancer cells expressing hERα (MELN) were used to quantify the estrogenic activity of 25 surface water samples of the Danube River, for which chemicals have been previously quantified. Most samples had a low estrogenic activity below 0.1 ng/L 17β-estradiol-equivalents that was more often detected by MELN cells, while ZELHβ2 response tend to be lower than predicted based on the chemicals identified. Nevertheless, both bioassays quantified well a higher estrogenic activity at two sites, which was confirmed in vivo using a transgenic zebrafish assay. The results are discussed considering the effect-based trigger values proposed for water quality monitoring.
(Environmental Toxicology and Pharmacology. vol. 78, n° 1382-6689, pp. art. 103401, 26/04/2026)
SEBIO, INERIS, URCA, ULH, NU, URCA, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, INERIS, LPTC, UB, CNRS, UFZ, RWTH Aachen
SESAM mode-locked Tm:LuYO 3 ceramic laser generating 54-fs pulses at 2048 nm
(Applied optics. vol. 59, n° 1559-128X, pp. 10493, 26/04/2026)
JSNU, HNU, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CIMAP - UMR 6252, UNICAEN, NU, IRAMIS, CEA, ENSICAEN, NU, CNRS, IRMA, UNICAEN, NU, ENSICAEN, NU, CEA, UNIROUEN, NU, INSA Rouen Normandie, INSA, NU, CNRS
Organotropism and biomarker response in oyster Crassostrea gigas exposed to platinum in seawater
Platinum (Pt) is a technology critical element (TCE) for which biogeochemical cycles are still poorly understood. This lack of knowledge includes Pt effects on marine organisms, which proved to be able to bioconcentrate this trace element. Oysters Crassostrea gigas were exposed to stable Pt isotope spiked daily in seawater for 35 days. Seawater was renewed daily and spiked (with Pt(IV)) to three nominal Pt concentrations (50, 100, and 10,000 ng L−1) for two replicate series. Organotropism study revealed that gills, and to a lesser extent mantle, are the key organs regarding Pt accumulation, although a time- and concentration-dependent linear increase in Pt levels occurred in all the organs investigated (i.e., digestive gland, gonads, gills, mantle, and muscle). In oysters exposed to Pt concentrations of 10,000 ng L−1, significant biomarker impairments occurred, especially at cellular levels. They reflect altered lipofuscin and neutral lipid contents, as well as intralysosomal metal accumulation. These observations were attributed to activation of excretion/detoxification mechanisms, including Pt elimination through feces and clearly support the importance of the digestive gland in the response to direct Pt exposure. Despite relatively constant condition index, the integrative biological response (IBR) index suggests a generally decreasing health status of oysters
(Environmental Science and Pollution Research. vol. 27, n° 0944-1344, pp. 3584-3599, 26/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UPV / EHU
Des concrétions fuligineuses en contextes archéologiques : quel potentiel informatif ?
Les spéléothèmes (concrétions carbonatées de grottes) sont des archives naturelles qui se caractérisent par leur capacité à enregistrer les environnements passés ainsi que par leur haute résolution temporelle, en particulier lorsqu’ils sont laminés annuellement. Leur potentiel d’étude ne se limite pas qu’aux recherches sur les reconstitutions paléo-climatiques. Les concrétions peuvent par exemple piéger des particules anthropiques comme de la suie, et ces concrétions fuligineuses ont un fort potentiel informatif en archéologie. Dans cet article, nous présenterons les potentiels d’application archéologique de l’analyse fuliginochronologique à travers plusieurs cas, dans des contextes temporels différents. Les cas les plus récents (en Belgique, en France et en Slovénie), pour lesquels nous disposons parfois d’informations historiques et textuelles autorisant un contrôle des faits archéologiques enregistrés, permettront de valider le potentiel d’archive micro-chronologique des spéléothèmes dans le cadre d’une étude fuliginochronologique. Ensuite, nous étendrons l’utilisation de cette méthode à un site paléolithique français afin de mettre en lumière le potentiel informatif de cette approche en préhistoire.
(Géomorphologie : relief, processus, environnement. vol. 26, n° 1266-5304, pp. 241-254, 26/04/2026)
UP1 UFR03, UP1, ArScAn, UP1, UP8, UPN, MCC, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LAMPEA, AMU, CNRS, MC, TRACES, EHESS, UT2J, Comue de Toulouse, MCC, Inrap, CNRS
Extreme Wave Events on Barrier Reefs: A Driver for Critical Regime?
This paper describes the hydrodynamic regimes reached over barrier reefs during extreme wave events. The study is based on a combined approach relying, on one hand, on an extensive in-situ experiment over the Ouano reef-lagoon system, New Caledonia and, on the other hand, on wave-resolving numerical modeling.
(Journal of Coastal Research. vol. 95, n° 0749-0208, pp. 654-658, 26/04/2026)
SIAME, UPPA, MIO, IRD, AMU, INSU - CNRS, UTLN, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, INSU - CNRS, UM, CNRS, UA, LOPS, IRD, IFREMER, INSU - CNRS, UBO EPE, CNRS