Rôle des interactions plante-plante dans la réponse des forêts au changement climatique : l’exemple des forêts de chêne sessile et de hêtre dans les Pyrénées Occidentales
Les recherches concernant l’impact du changement climatique sur les forêts, telles que les modèles d’enveloppes climatiques et les modèles phénologiques, ignorent les interactions biotiques. Notre objectif est l’étude du rôle médiateur des interactions chêne-hêtre dans leur réponse au changement climatique dans les Pyrénées Occidentales. Des études préliminaires suggèrent que des différences importantes de sensibilité phénologique à la température entre ces espèces pourraient expliquer leur répartition altitudinale actuelle et l’évolution de leur balance compétitive avec le changement climatique. Nous présentons ici les résultats d’une expérimentation réalisée in situ et ayant pour but de quantifier les variations d’interactions entre des plantules de ces deux espèces et les arbres adultes le long d’un gradient altitudinal. Les résultats pour la survie des plantules montrent une augmentation importante de la compétition en altitude pour le chêne seulement. C’est le manque de chaleur à l’ombre du hêtre à haute altitude qui limite actuellement la longueur de la saison de végétation du chêne et sa progression en altitude. Le réchauffement climatique devrait diminuer la compétition subie par le chêne relativement au hêtre de par sa plus grande sensibilité phénologique à la température et ainsi exacerber les effets du changement climatique sur la migration altitudinale de ces deux espèces.
(Innovations Agronomiques. vol. 47, n° 1958-5853, pp. 97-108, 23/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UNINE, BioGeCo, INRA, UB
Selectivity of water obstacles on glass eel migration wave
Physical obstacles to upstream migration such as dams are a major impairment of natural colonisation and dispersion of migratory fish such as eels. Dams and obstacles increase fish energy expenditure, even when they are equipped with fish friendly devices. Besides, local accumulation of eels below dams increase the mortality associated with predation. Obstacles may also select on different traits of life history. While quantitative impact of dams is subjected to numerous studies, little is known about their intra-specific selectivity. Even the fishway efficiency analyses are scarcely hinting at their potential selective effect (Castro-Santos 2004; Noonan, Grant & Jackson 2012). The objective of this study was to pinpoint phenotypic traits predisposing glass eels to dams successful passage. In a preliminary approach we measured the transcription level of 15000 known eel genetic sequences in three main tissues (brain, liver and muscle) from wild individuals sampled on three successive river segments separated by dams. Interestingly, whereas no significant difference was observed in muscle and liver, segment-specific gene expression profiles were observed in brain. Surprisingly, the set of regulated genes was involved in synaptic plasticity, associated with animal cognition. In this study, by means of qPCR analysis of targeted genes, behavioral tests on experimental fishway and common garden experiment, the objective was to give insight into how genes related to learning and memory are associated with climbing behavior of fish.
(pp. 27, 23/04/2026)
UR EABX, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, EDF [E.D.F.]
Seasonal changes in stable carbon and nitrogen isotope compositions of bat guano (Guadeloupe)
Stable isotope compositions of fossil bat guano have recently been developed as a proxy for reconstructing terrestrial paleoenvironments. However, our understanding of exactly how accurately these isotope compositions reflect seasonal variations remains limited. Here, we present a study of modern guano of phytophagous bats collected monthly over a one-year period at two roosting sites in Guadeloupe. The aim is to assess the degree to which seasonal climate and environmental variations are reflected in carbon and nitrogen isotope compositions from bat guano, as well as to evaluate the potential use of guano from phytophagous bats as a paleoenvironmental record. Our results show that stable isotope compositions vary locally, suggesting that guano of phytophagous bats accurately records local environmental conditions. Additionally, stable isotope compositions reflect seasonal variations influencing bat diet that lead to modifications of up to 2‰ of the carbon isotope compositions from feces. However, these variations are not correlated solely with climate variables as there is no straightforward relationship between climate, vegetation and bat diet over a one-year period. Moreover, these seasonal variations drive one of the bat colonies to occasionally consume insects, which can be traced as a seasonal shift in %N (up to 4.5%) and carbon isotope compositions (up to 5.6‰). Seasonal changes in isotope compositions are still lower than expected variations from fossil feces, confirming the potential use of feces from phytophagous bats as a reliable paleoenvironmental proxy.
(Palaeogeography, Palaeoclimatology, Palaeoecology. vol. 440, n° 0031-0182, pp. 524-532, 23/04/2026)
PACEA, UB, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Genetic and physiological responses of three freshwater diatoms to realistic diuron exposures
This study examined the effects of diuron on strains of three major freshwater diatom species, Eolimna minima, Nitzschia palea and Planothidium lanceolatum. These species are frequently recorded in the Morcille river, where diuron runs off during phytosanitary treatments of the vineyards around. Here, there were three diatom exposure groups for each species: 0, 1 and 10µg/L diuron during a fourteen-day laboratory assessment. Diuron water concentration, cell number, photosynthetic activity and gene expression were assessed at 6h, 2, 7 and 14 days after contamination. Diuron exposure altered photosynthetic activity in that the optimal quantum yield of photosystem II (PSII) decreased between 40 and 50% and, for Planothidium lanceolatum at 10µg/L, there was complete inhibition. Genetic responses indicated diuron effects on both photosystem II and mitochondrial metabolism in all three species at both diuron exposure levels. Thus, analysis of the expression of psaA, d1, cox1, nad5 and 12s could be an early biomarker to detect pesticide pollution. Overall, this study revealed differences in diuron sensitivity among the three species: Eolimna minima and Nitzschia palea appeared to be more tolerant than Planothidium lanceolatum. These results suggest that the development of molecular tools, and more precisely of biomarkers, will aid in early assessment of contamination and water quality.
(Environmental Science and Pollution Research. vol. 22, n° 0944-1344, pp. 4046-4055, 23/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR EABX, IRSTEA
Leaf litter degradation in highly turbid transitional waters: preliminary results from litter-bag experiments in the Gironde Estuary
The rates of decomposition of oak (Quercus robur) leaves have been examined using litter bags in a very high turbidity macrotidal estuary, the Gironde Estuary (S.W. France). The first experiments show a marked decrease in the decomposition rate of oak leaves at the water-sediment interface (mud-contact: anoxic conditions, reduced physical fragmentation) in comparison to the water column. The results point out the impact of hydrodynamic conditions on leaf litter degradation in such fluvio-estuarine systems. Regarding the aquatic-terrestrial linkage, our observations suggest direct changes in leaf decomposition kinetics and then, a potential delay on the recycling and transport processes of coarse particulate organic matter, especially in a context of modification of the natural water flow, due to global and land use changes.
(Geodinamica Acta. vol. vol. 27, n° 0985-3111, pp. pp. 60-66, 23/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, EDF R&D LNHE, EDF R&D, EDF [E.D.F.], LEFE, INEE-CNRS, CNRS, UT3, Comue de Toulouse, CNRS, Toulouse INP, Comue de Toulouse
Modelling analysis of tidal bore formation in convergent estuaries
(23/04/2026)
CARDAMOM, IMB, UB, Bordeaux INP, CNRS, Inria, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Étude de la contamination de la masse d’eau en pesticides, comparatif entre prélèvements ponctuels et échantillonnage passif – applications à des eaux naturelles et à des effluents de zones industrielles de la région bordelaise
Cent dix-neuf pesticides ont été recherchés dans des eaux naturelles de la Jalle d’Eysines, un cours d’eau aquitain, et dans des effluents de zones industrielles bordelaises, au cours de deux campagnes de prélèvement. Les molécules ont été quantifiées à partir de prélèvements moyennés sur 24 h. En parallèle, des échantillonneurs passifs de type POCIS (Polar Organic Chemicals Integrative Sampler) ont permis d’établir un suivi qualitatif. Les profils moléculaires au sein d’un même type de masse d’eaux sont identiques, mais diffèrent entre une eau naturelle et un effluent de zone industrielle. L’approche qualitative via les POCIS a permis de quantifier des molécules non détectées lors des prélèvements moyennés, tant pour les eaux de la Jalle d’Eysines que pour celles des zones industrielles. Les échantillonneurs passifs semblent donc prometteurs pour la caractérisation de masses d’eaux de différentes origines, en ce qui concerne les pesticides dont le log KOW est compris entre un et quatre. Il est cependant nécessaire de développer la démarche PRC (Performance Reference Compounds) afin d’y ajouter une visée quantitative.
(Revue des Sciences de l'Eau / Journal of Water Science. vol. 28, n° 0992-7158, pp. 223-228, 23/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UB
The ocean sampling day consortium
Ocean Sampling Day was initiated by the EU-funded Micro B3 (Marine Microbial Biodiversity, Bioinformatics, Biotechnology) project to obtain a snapshot of the marine microbial biodiversity and function of the world’s oceans. It is a simultaneous global mega-sequencing campaign aiming to generate the largest standardized microbial data set in a single day. This will be achievable only through the coordinated efforts of an Ocean Sampling Day Consortium, supportive partnerships and networks between sites. This commentary outlines the establishment, function and aims of the Consortium and describes our vision for a sustainable study of marine microbial communities and their embedded functional traits.
(GigaScience. vol. 4, pp. 27, 23/04/2026)
NERC, AD2M, SBR, UPMC, CNRS, UPMC, CNRS, IOLR, AWI, HCMR, DTU, SBR, UPMC, CNRS, UCC, IRB, OFFIS, ULISBOA, ISMAR, CNR, GEOMAR, SYKE, NOAA, UiB, CIIMAR, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CINVESTAV, USC, LOMIC, OOB, UPMC, CNRS, UPMC, CNRS, UDELAR, CSIRO, SARDI, VLIZ, CEFAS, UAlg, LOV, OOVM, UPMC, INSU - CNRS, CNRS, UPMC, INSU - CNRS, CNRS, UTAS, CRIOBE, UPVD, EPHE, PSL, CNRS, UPV / EHU, UM5, USMBA, UAE, BAS, EMBL-EBI, UBO EPE, DEÜ, Unipd, NTU, IPMA, IGS, AMU, CNRS, OGS, RUSL, USM, UiO, ICM, CSIC, MU, SZN, UNIVPM, BAS, NERC, UAF, MBL, ANL, UC Berkeley, UC
The most vagile host as the main determinant of population connectivity in marine macroparasites
Although molecular ecology of macroparasites is still in its infancy, general patterns are beginning to emerge, e.g. that the most vagile host in a complex life cycle is the main determinant of the population genetic structure of their parasites. This insight stems from the observation that populations of parasites with only freshwater hosts are more structured than those with terrestrial or airborne hosts. Until now, the same has not been tested for marine systems, where, in theory, a fully marine life cycle might sustain high dispersal rates because of the absence of obvious physical barriers in the sea. Here, we tested whether a marine trematode parasite that utilises migratory birds exhibited weaker population genetic structure than those whose life cycle utilises marine fish as the vagile host. Part of the mitochondrial cytochrome c oxidase 1 (COI) gene was sequenced from individual sporocysts from populations along the Atlantic coast of Europe and North Africa. Strong population structure (Φst = 0.25, p < 0.0001) was found in the fully marine trematode Bucephalus minimus (hosted by fish), while no significant structure (Φst = 0.015, p = 0.19257) was detected in Gymnophallus choledochus (hosted by birds). However, demographic models indicate recent colonisation rather than high dispersal as an alternative explanation of the low levels of structure observed in G. choledochus. Our study is the first to identify significant genetic population structure in a marine autogenic parasite, suggesting that connectivity between populations of marine parasites can be limited despite the general potential for high dispersal of their hosts in the marine environment.
(Marine Ecology Progress Series. vol. 520, n° 0171-8630, pp. 85-99, 23/04/2026)
NIOZ, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UM5, UCC
Unexpected Levels of Biological Activity during the Polar Night Offer New Perspectives on a Warming Arctic
Summary The current understanding of Arctic ecosystems is deeply rooted in the classical view of a bottom-up controlled system with strong physical forcing and seasonality in primary-production regimes. Consequently, the Arctic polar night is commonly disregarded as a time of year when biological activities are reduced to a minimum due to a reduced food supply. Here, based upon a multidisciplinary ecosystem-scale study from the polar night at 79°N, we present an entirely different view. Instead of an ecosystem that has entered a resting state, we document a system with high activity levels and biological interactions across most trophic levels. In some habitats, biological diversity and presence of juvenile stages were elevated in winter months compared to the more productive and sunlit periods. Ultimately, our results suggest a different perspective regarding ecosystem function that will be of importance for future environmental management and decision making, especially at a time when Arctic regions are experiencing accelerated environmental change.
(Current Biology. vol. 25, n° 0960-9822, pp. 2555-2561, 23/04/2026)
UiT, UNIS, NIVA, SAMS, CEOE, NTNU, NTNU, SPBU, LEMAR, IRD, IFREMER, UBO EPE, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, AWI