Shift from short‐term competition to facilitation with drought stress is due to a decrease in long‐term facilitation
Disentangling short- and long-term neighbour effects, using both removal and observational methods within a single experiment, has strongly improved our understanding of the driving mechanisms of plant–plant interactions. However, there has been no attempt to assess two important underlying processes of their changes along gradients, either environmental-severity (changes in target performance without neighbours) or neighbour-traits (changes in performance with neighbours) effects, the former previously shown in alpine communities to be involved in competition and the latter in facilitation. We addressed this goal in an experiment conducted in continental saline depressions (sebkhas) from the Mediterranean arid climate of central Tunisia. We quantified short- and long-term effects of dominant shrubs, transplanting three target grass species in open, nurse and removed-nurse microhabitats of two habitats of different salinity levels in height sebkhas. The design extended greographically from central Tunisia to the Libyan border, 500 km southeastward. We used the relative interaction index to calculate short- and long-term effects before and after the dry summer seasons and environmental-severity and neighbour-trait effects. Short-term effects were slightly negative and long-term effects strongly positive before the dry summer season in the two habitats. Short-term effects switched to positive with increasing drought stress, due to an environmental-severity effect, whereas long-term effects decreased due to a neighbour-trait effect. Salinity did not affect neither short- nor long-term shrub effects. Soil moisture measurements showed that both changes were due to vanishing shrub soil engineering-effects during the summer drought. We conclude that an increase in short-term facilitation with increasing drought stress through time, apparently supporting the stress gradient hypothesis, might be due to a decrease in long-term facilitation. Thus, we recommend using, as much as possible, both the removal and observational methods in experiments assessing changes in plant–plant interactions along stress gradients to avoid wrong conclusions.
(Oikos. vol. 130, n° 0030-1299, pp. 29-40, 21/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Cell and tissue level responses in mussels Mytilus galloprovincialis dietarily exposed to PVP/PEI coated Ag nanoparticles at two seasons
Silver nanoparticles (Ag NPs) are present in numerous consumer products due to their antimicrobial and other unique properties, thus concerns about their potential input into aquatic ecosystems are increasing. Toxicity of Ag NPs in waterborne exposed aquatic organisms has been widely investigated, but studies assessing the potential toxic effects caused after ingestion through the food web, especially at low realistic concentrations, remain scarce. Moreover, it is not well known whether season may influence toxic effects of Ag NPs. The main objective of this study was to determine cell and tissue level responses in mussels Mytilus galloprovincialis dietarily exposed to poly-N-vinyl-2-pirrolidone/polyethyleneimine (PVP/PEI) coated 5 nm Ag NPs for 1, 7 and 21 days both in autumn and spring. Mussels were fed every day with microalgae Isochrysis galbana exposed for 24 h to a low dose (1 μg Ag/L Ag NPs) in spring and to a higher dose (10 μg Ag/L Ag NPs) in spring and autumn. Mussels fed with microalgae exposed to the high dose accumulated Ag significantly after 21 days in both seasons, higher levels being measured in autumn compared to spring. Intralysosomal metal accumulation measured in mussel digestive gland and time- and dose-dependent reduction of mussels health status was similar in both seasons. DNA strand breaks increased significantly in hemocytes at both exposure doses along the 21 days in spring and micronuclei frequency showed an increasing trend after 1 and 7 days of exposure to 1 μg Ag/L Ag NPs in spring and to 10 μg Ag/L in both seasons. Values decreased after 21 days of exposure in all the cases. In conclusion, PVP/PEI coated 5 nm Ag NPs ingested through the food web were significantly accumulated in mussel tissues and caused adverse cell and tissue level effects both in autumn and in spring.
(Science of the Total Environment. vol. 750, n° 0048-9697, pp. 141303, 21/04/2026)
UPV / EHU, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Les plans d'eau face aux changements climatiques
Ces milieux aquatiques fournissent de nombreux services écosystémiques, en assurant des fonctions de support (production primaire, biodiversité), de régulation (épuration des nutriments, régulation des flux hydriques), d’approvisionnement (eau potable, irrigation, énergie) et socio-culturels (loisir, tourisme). Souvent perçus à tort comme immuables, stables et en dehors de toute pression, les plans d’eau font l’objet de multiples usages anthropiques, impactant leur fonctionnement. Le changement climatique en cours ne fait qu’exacerber ces impacts et accélérer la dégradation des milieux ; à l’échelle régionale, ses effets restent encore à évaluer. Dans cet ouvrage, nous avons souhaité illustrer, de la manière la plus large possible, la variété des systèmes lentiques présents en Nouvelle-Aquitaine, ainsi que les lacunes de connaissance que diverses études mettent en évidence. Le but de cet ouvrage est d’apporter des éclairages scientifiques pour l’aide à la décision et aux choix politiques, et d’accompagner l’appropriation citoyenne des connaissances. Notre souhait ultime serait que ces lieux emblématiques, source de bien-être et de services, puissent continuer à recouvrir leurs rôles fonctionnels dans le futur.
(pp. 56, 21/04/2026)
Bordeaux INP, UBM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CARRTEL, USMB [Université de Savoie] [Université de Chambéry], INRAE, Fédération OSUG, CEDETE, UO, UR EABX, INRAE, BRGM, ENSEGID, IRSTEA, E2Lim, IMPEO, UNILIM, ECOBIO, UR, INEE-CNRS, CNRS, CNRS, IPSL (FR_636), ENS-PSL, PSL, UVSQ, CEA, INSU - CNRS, X, IP Paris, CNES, SU, CNRS, UPCité, IRSTEA, DIRSE, RURALITES [Poitiers], UP
Latitudinal influence on gametogenesis and host–parasite ecology in a marine bivalve model
Reproduction and parasites have significant impacts on marine animal populations globally. This study aimed to investigate the associative effects of host reproduction and a host–parasite interplay on a marine bivalve, along a geographic gradient of latitude. Cockles Cerastoderma edule were sampled from five European sites (54°N to 40°N), between April 2018 and October 2019. A histological survey provided data on trematode (metacercaria and sporocyst life stages), prevalence, and cockle stage of gametogenesis to assess the influence of a latitudinal gradient on both interplays. Sex ratios at the northernmost sites were skewed toward females, and spawning size was reduced at the lower latitudes. Trematode infection did not follow a latitudinal gradient. Localized site-related drivers, namely seawater temperature, varied spatially, having an impact on cockle–trematode interactions. Spawning was related to elevated temperatures at all sites. Prolonged spawning occurred at southern latitudes, where seawater temperatures were warmer. Trematode prevalence and the impact of trematodes on gametogenesis were found to be spatially variable, but not latitudinally. Therefore, it is not possible to determine the likelihood of boom and bust events in cockles, based on the latitudinal location of a population. In terms of sublethal impacts, it appeared that energy was allocated to reproduction rather than somatic growth in southern populations, with less energy allocated to reproduction in the larger, northern cockles. The demonstrated spatial trend of energy allocation indicates the potential of a temporal trend of reduced cockle growth at northern sites, as a result of warming sea temperatures. This awareness of the spatially varying drivers of populations is crucial considering the potential for these drivers/inhibitors to be exacerbated in a changing marine environment.
(Ecology and Evolution. vol. 11, pp. 7029-7041, 21/04/2026)
UCC, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
The Terebelliformia-Recent Developments and Future Directions
(Diversity. vol. 13, n° 1424-2818, pp. 60, 21/04/2026)
USP, USP, LECOB, SU, CNRS, OOB, SU, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Peer Community In… A free recommendation process of preprints based on peer reviews
(21/04/2026)
UMR CBGP, Cirad, UM, IRD [Occitanie], INRAE, Institut Agro, ISA, UNS, CNRS, INRAE, UniCA, DipSO, INRAE, ECOSYS, INRAE, IFREMER, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
1H-NMR metabolomics profiling of zebra mussel (Dreissena polymorpha): A field-scale monitoring tool in ecotoxicological studies
Biomonitoring of aquatic environments requires new tools to characterize the effects of pollutants on living organisms. Zebra mussels (Dreissena polymorpha) from the same site in north-eastern France were caged for two months, upstream and downstream of three wastewater treatment plants (WWTPs) in the international watershed of the Meuse (Charleville-Mézières “CM” in France, Namur “Nam” and Charleroi “Cr” in Belgium). The aim was to test 1H-NMR metabolomics for the assessment of water bodies’ quality. The metabolomic approach was combined with a more “classical” one, i.e., the measurement of a range of energy biomarkers: lactate dehydrogenase (LDH), lipase, acid phosphatase (ACP) and amylase activities, condition index (CI), total reserves, electron transport system (ETS) activity and cellular energy allocation (CEA). Five of the eight energy biomarkers were significantly impacted (LDH, ACP, lipase, total reserves and ETS), without a clear pattern between sites (Up and Down) and stations (CM, Nam and Cr). The metabolomic approach revealed variations among the three stations, and also between the upstream and downstream of Nam and CM WWTPs. A total of 28 known metabolites was detected, among which four (lactate, glycine, maltose and glutamate) explained the observed metabolome variations between sites and stations, in accordance with chemical exposure levels. Metabolome changes suggest that zebra mussel exposure to field contamination could alter their osmoregulation and anaerobic metabolism capacities. This study reveals that lactate is a potential biomarker of interest, and 1H-NMR metabolomics can be an efficient approach to assess the health status of zebra mussels in the biomonitoring of aquatic environments.
(Environmental Pollution, n° 0269-7491, pp. 116048, 21/04/2026)
SEBIO, INERIS, URCA, ULH, NU, URCA, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LIEC, INSU - CNRS, UL, CNRS, ICMR, URCA, INC-CNRS, URCA, CNRS, URCA, CNRS, SWDE
Contaminants of emerging concern in the Seine river basin: Overview of recent research
For over 30 years, the sources and the transfer dynamics of micropollutants have been investigated in the PIREN-Seine programme. Recent works included a wide range of chemicals and biological contaminants of emerging concern (i.e. contaminants whose occurrence, fate and impact are scarcely documented). This chapter presents a brief overview of research recently conducted on contaminants as diverse as macro- and microplastics, poly- and perfluoroalkyl substances (PFASs), pathogenic protozoa, antibiotics and the associated antibiotic resistance. The multiscalar study of plastics and PFASs at a large spatial scale is rare; the results produced in recent years on the Seine River catchment have provided an original contribution to the investigation of the dynamics of these contaminants in urban environments. The results also highlighted that pathogenic protozoa are ubiquitous in the Seine River basin and that the contamination of bivalves such as Dreissena polymorpha could reflect the ambient biological contamination of watercourses. The widespread occurrence of antibiotics in the Seine River was demonstrated, and it was shown that the resistome of biofilms in highly urbanised rivers constitutes a microenvironment where genetic support for antibiotic resistance (clinical integrons) and resistance genes for trace metals are concentrated.
(. vol. 90, pp. 355-380, 21/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEESU, ENPC, UPEC UP12, M2C, UNICAEN, NU, INSU - CNRS, UNIROUEN, NU, CNRS, SEBIO, INERIS, URCA, ULH, NU, URCA, CNRS, GERS-LEE, METIS, EPHE, PSL, INSU - CNRS, SU, CNRS, SIAAP
The role of physical disturbance for litter decomposition and nutrient cycling in coastal sand dunes
Disturbance increases ecosystem functioning in productive habitats but its effect in stressful conditions is less documented, although this is crucial for understanding the resilience of disturbed systems to natural and anthropogenic disturbances. Our goal is to assess the influence of physical disturbance for ecosystem functioning in coastal sand dunes. We set up an experimental design, including two treatments in four blocks, in a four km-long dune site from South West France. We simulated physical disturbance from marine and wind origin, digging Experimental Notches (EN), in the incipient (West EN treatment) and established foredunes (East EN treatment), respectively and compared the effects of EN to controls along transects including 13 positions from the beach to the transition dune behind ENs. We sampled litter decomposition rate, elevation variation, wind abrasion, sand grain size and vegetation composition. We also used drones to quantify sand deposition sheets during severe winter storms. Litter decomposition rate was the highest where sand accumulated the most, at the ecotone between the established foredune and transition dune and in the East EN treatment. This increase of ecosystem functioning was correlated to wind patterns. However, there was also a strong alongshore variability, with important sand deposition sheets occurring in some blocks depending on dune geomorphology. Vegetation composition was mainly influenced by shoreline distance, but also by the block and EN treatment, with a strong interaction between these three effects. We conclude that physical disturbance increase ecosystem functioning in the stressful conditions of the Atlantic sand dunes, only when sand accumulates, whereas excessive disturbances enhancing sand erosion are not favorable for ecosystem functioning.
(Ecological Engineering. vol. 162, n° 0925-8574, pp. 106181, 21/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ONF
Headland Rip Modelling at a Natural Beach under High-Energy Wave Conditions
A XBeach surfbeat model is used to explore the dynamics of natural headland rip circulation under a broad range of incident wave conditions and tide level. The model was calibrated and extensively validated against measurements collected in the vicinity of a 500-m rocky headland. Modelled bulk hydrodynamic quantities were in good agreement with measurements for two wave events during which deflection rips were captured. In particular, the model was able to reproduce the tidal modulation and very-low-frequency fluctuations (≈1 h period) of the deflection rip during the 4-m wave event. For that event, the synoptic flow behaviour shows the large spatial coverage of the rip which extended 1600 m offshore at low tide, when the surf zone limit extends beyond the headland tip. These results emphasize a deflection mechanism different from conceptualised deflection mechanisms based on the boundary length to surf zone width ratio. Further simulations indicate that the adjacent embayment is responsible for the seaward extent of the rip under energetic wave conditions. The present study shows that the circulation patterns along natural rugged coastlines are strongly controlled by the natural variability of the coastal morphology, including headland shape and adjacent embayments, which has implications on headland bypassing expressions.
(Journal of Marine Science and Engineering. vol. 9, n° 2077-1312, pp. 1161, 21/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS