Résumé
IntroductionEvidence of insect herbivory on fossilized leaves is widely used to ascertain the evolution of feeding strategies, and trophic changes in response to phenomena such as climate change. However, leaves can decompose somewhat before fossilization, and the extent to which decomposition may bias estimates of insect herbivory in deep time is far from fully understood. There are many points at which evidence may become obscured as a leaf travels from its parent tree into the depositional environment where it fossilizes.Materials & methodsHere, we compare evidence of plant–insect interactions on live leaves and in leaf litter collected directly beneath the same trees to provide an initial glimpse into the first stage at which decomposition may lead to eventual bias in paleontological studies. We measure the frequency and richness of insect damage types on the leaves of Fagaceae in four Mediterranean localities in Turkey and France.Results & discussionWe observed variations in insect damage on litter leaves compared to those on trees, with some localities showing reduced damage richness, lower damage frequency, or both. This observation was particularly pronounced for external damage types. Galls stood out due to their relatively consistent preservation in leaf litter, suggesting their utility as a more dependable indicator for interpreting paleoecological conditions. Our study builds upon existing methods in paleoecology, highlighting their value in detecting environmental signals and advocating for further refinements to capture the ecological dynamics of the past more comprehensively.
Auteurs, date et publication :
Auteurs Benjamin Adroit , Sandra R. Schachat , H. Tuncay Güner , Jean-Philippe Orts , Thomas Denk
Publication : Frontiers in Ecology and Evolution
Date : 2025
Volume : 13
Catégorie(s)
#CNRS #FORET O3HPRésumé
Mangrove forests store significant amounts of blue carbon, mainly as soil organic matter. Insights into mangrove organic matter are limited, despite its importance for understanding blue carbon accumulation and vulnerability to global change. Here, we quantified soil organic matter preserved through chemical recalcitrance and association with the mineral phase, as key factors influencing blue carbon persistence. We found that the nature of the soil organic matter varied with mangrove geomorphic settings. Delta settings were dominated by presumably the most persistent soil organic matter associated with minerals, while open coast karstic settings contained mostly particulate soil organic matter, likely preserved due to low microbial activity. Across mangrove soil depths, there was little difference in soil organic matter pools. The soil organic matter pool across mangroves’ geomorphic settings exhibited greater variation than that observed across all terrestrial biomes. These findings underscore the need to tailor mangrove conservation and restoration to geomorphic settings.
Auteurs, date et publication :
Auteurs Marie Arnaud , Catherine E. Lovelock , Marion Maceiras , Dang Thuong-Huyen , Sarah Robin , Samuel Abiven , Amrit Kumar Mishra , Syed Hilal Farooq , Tuhin Bhadra , Axel Felbacq , Cyril Marchand , Nicolas Bottinelli , Thanh-Phong Le , Ahmad Aldrie Amir , Cornelia Rumpel
Publication : Communications Earth & Environment
Date : 2025
Volume : 6
Issue : 1
Pages : 743
Catégorie(s)
#CNRS #Ecotron IleDeFranceRésumé
The effects of veterinary anti-parasitic compounds on wild fish species and their parasites are poorly investigated. Bithionol, an antibacterial, anthelmintic, and algaecide, is commonly used in aquaculture to control parasitic infections, particularly acanthocephalan (spiny-headed worm) infestations. This study aims to evaluate the impacts of bithionol exposure on European chub (Squalius cephalus) originating from natural populations, and its naturally occurring acanthocephalans. We assessed fish behavioral responses, alongside physiological markers, in addition with response of their parasites (number, size, reproductive outputs). Our results indicate that bithionol exposure induces behavioral alterations (increased opercular movements, altered spatial positioning), but does not significantly affect key physiological markers. Furthermore, acanthocephalan parasites influence host immunity and behavior, but their presence does not mitigate (decrease or increase) the effects of bithionol on fish. Contrary to expectations, bithionol treatment does not affect parasites, suggesting potential resistance or environmental factors affecting its efficacy.
Auteurs, date et publication :
Auteurs Léa Lorrain-Soligon , Simon Agostini , Clotilde Biard , Beatriz Decencière , Baptiste Lemaire , Alexis Millot , Sandrine Meylan , Eliott Salles , Aurélie Goutte
Publication : Environmental Toxicology and Pharmacology
Date : 2025
Volume : 118
Pages : 104782
Catégorie(s)
#CNRS #ENS #PLANAQUARésumé
Soil contamination with trace metals and metalloids (TMM) can negatively impact biota in ways not captured by chemical analyses alone. This study evaluates the effectiveness of two integrated biological indices (Total Enzyme activity Index – TEI, Integrated Biomarker Response – IBR) in detecting toxicity effects on biota in soils subjected to long-term TMM contamination. An ex situ biotest using soils from Peisey-Nancroix (France), a former Pb–Ag mining site, was conducted with the sensitive plant Arabidopsis thaliana to identify relevant biomarkers and develop key biological indices. The results demonstrate clear TMM toxicity, reflected in decreased microbial functioning (evidenced by reduced TEI) and impaired plant growth (shown by elevated IBR). These indices were then assessed in situ at the same site. Unexpectedly, TEI—despite its status as an early indicator of soil degradation—showed no relationship with long-term TMM toxicity or Pb-mobility, whereas IBR—derived from endogenous plant biomarkers—strongly correlated with TMM contamination and bioavailable Pb levels, particularly in the sensitive species Geranium sylvaticum. These results indicate that IBR is a reliable proxy for ecological risk and TMM bioavailability in chronically contaminated soils.
Auteurs, date et publication :
Auteurs Marion Sarah Deville-Cavellin , Floriane Guillevic , Christelle Gonindard-Melodelima , Sylvain Campillo-Cressot , Frédéric Laporte , Cindy Arnoldi , Magali Rossi , Arnaud Foulquier , Muriel Raveton
Publication : Chemosphere
Date : 2025
Volume : 393
Pages : 144770
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Abstract. Organic carbon derived from roots is a major input fuelling soil organic carbon stocks, especially in agricultural systems, where aboveground biomass might be harvested. However, root sampling for carbon monitoring excludes net rhizodeposition, i.e. the organic compounds released by the roots that have not been rapidly mineralised, and some of the finest root debris, because this fraction of root-derived carbon can not be directly quantified in the field. To compensate for this shortfall, we set up a two-month experiment with multi-pulse 13C-CO2 labellings of 12 crops to quantify these carbon pools at harvest, operationally grouped under the term SOCnew. We also investigated the spatial distribution of belowground carbon inputs within the soil profile. Lastly, in order to follow the fate of this carbon after the plant death, we performed a 524-day litterbag incubation in the field using the labelled material. We found that SOCnew accounted for 27 % of belowground carbon inputs at harvest. It was not correlated to carbon amounts of the shoots, but was positively correlated to root carbon (R2 = 0.14). The vertical distribution of SOCnew tended to follow the one of roots. The majority was recovered in the bulk soil, rather than adhering to the roots. We showed that SOCnew had a greater persistence time in the soils than roots in the mid-term. However, these findings were marked by high variability because the small quantities of carbon involved make it difficult to assess persistence by isotopic difference. These results suggest that net rhizodeposition and fine root debris should be taken into account in organic carbon management of soils as it refines our estimation of belowground inputs. However, their low predictability, due to the diversity of products and processes, is still a barrier.
Auteurs, date et publication :
Auteurs Baptiste Hulin , Florent Massol , Simon Chollet , Francis Dohou , Stéphane Paolillo , Samuel Abiven
Publication : EGUsphere
Date : 2025
Pages : 1-24
Catégorie(s)
#CNRS #Ecotron IleDeFranceRésumé
Increasing climate warming and summer droughts are known to affect mountain plant communities, their functional traits and life strategies. However, little is known about how strongly and efficiently communities respond to climate change, and how tightly plant responses are linked to responses of ecosystem functions. To test this, we transplanted alpine plant communities to subalpine conditions, exposing them to warming and drying. We compared these transplanted communities to alpine and subalpine control communities to assess their responses. Five years after transplantation, we found slower growth (e.g. lower leaf nitrogen) and more outsourcing strategies (e.g. lower specific root length) in the warmer and drier subalpine control communities compared to the alpine controls, probably due to drought. Traits of warmed alpine communities shifted toward subalpine controls. However, neither below- nor aboveground traits nor productivity of plants fully acclimated to subalpine conditions. Nevertheless, standard litter decomposition rates, arbuscular colonization and bacterial biomass showed no acclimation lag to the subalpine controls. Significant but insufficient acclimation of plant functional traits and strategies is prone to result in maladapted plant productivity, impairing competitiveness with better adapted subalpine species and leading to the temporally delayed loss of ecosystem features specific to alpine environments.
Auteurs, date et publication :
Auteurs Billur Bektaş , Gemma Rutten , Amélie Saillard , Rodrigue Friaud , Cindy Arnoldi , Julien Renaud , Maya Guéguen , Arnaud Foulquier , Jérôme Poulenard , Emilie Lyautey , Jean-Christophe Clément , Wilfried Thuiller , Tamara Münkemüller
Publication : New Phytologist
Date : 2026
Volume : 249
Issue : 3
Pages : 1173-1187
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Parasites are integral components of biodiversity, shaping host populations, food web dynamics, and ecosystem stability. However, they are influenced by environmental conditions and face growing threats. Despite growing evidence of global declines in parasite populations, the impacts of contaminants on their fitness in freshwater ecosystems remains poorly understood. In this study we investigated how environmental variability, host traits, and pollutant exposure affect the fitness and infection patterns of acanthocephalan parasites in chub (Squalius cephalus). Using a mesocosm approach, we assessed parasite infection intensity, size, and reproductive traits in relation to host size, body condition, site of capture, and seasonality, acknowledging that natural infections introduce variability. Moreover, we experimentally exposed chub to ubiquitous freshwater contaminants, including the pesticide imidacloprid, the pharmaceutical compounds paracetamol and diclofenac, and the herbicide S-metolachlor, at environmentally relevant concentrations. Our results indicate that host size was a key driver of parasite infection intensity. Parasite size increased over time but was independent of host condition and parasite density. While larger parasites produced more eggs, overall reproductive output declined in fish with better body condition and over time. Pollutant exposure yielded complex effects: chronic imidacloprid exposure (15 ng·g−1) reduced parasite size, while acute paracetamol exposure (16 μg·g−1) resulted in larger parasites but completely inhibited egg production. Other tested pollutants had no significant effects. These findings highlight the sensitivity of parasites to environmental stressors, the influence of host and environmental context, and the importance of accounting for natural variability and host-parasite interactions in ecotoxicological assessments of freshwater ecosystems.
Auteurs, date et publication :
Auteurs Léa Lorrain-Soligon , Simon Agostini , Alexandre Bauer , Beatriz Decencière , Côme Girard , Alexis Golven , Alexis Millot , Thierry Rigaud , Eliott Salles , Aurélie Goutte
Publication : International Journal for Parasitology
Date : 2025
Pages : 104761
Catégorie(s)
#CNRS #ENS #PLANAQUARésumé
Understanding the global Dole effect (DE) is essential for interpreting variations in the oxygen and water cycles. This study aims at refining the biological fractionation factors during respiration and photosynthesis in terrestrial plants and reassess their impact on the DE. Using multiplexed closed chamber experiments on five C3 and C4 plant species under soil and hydroponic conditions, we quantified isotopic discrimination during respiration (−16 to −21 ‰) and photosynthesis (approximately +3 to +5 ‰). These results confirm a previously reported positive discrimination associated with terrestrial photosynthesis, challenging the assumption of zero fractionation in this process. By incorporating these new estimates into updated calculations obtained using outputs of Earth system models, we obtain variations in DE between the last glacial maximum and the pre-industrial period consistent with ice core data. However, the changes around 6000 years ago cannot be explained solely by variations in terrestrial and oceanic productivity ratios, reinforcing the role of low-latitude hydrological processes. These results highlight the need to improve quantification of biological fractionation associated with the oxygen cycle in reconstructions of past atmospheric composition.
Auteurs, date et publication :
Auteurs Clémence Paul , Clément Piel , Joana Sauze , Ji-Woong Yang , Marie Bouchet , Olivier Jossoud , Arnaud Dapoigny , Daniele Romanini , Frédéric Prié , Sébastien Devidal , Roxanne Jacob , Alexandru Milcu , Amaëlle Landais
Publication : Quaternary Science Reviews
Date : 2025
Volume : 370
Pages : 109663
Catégorie(s)
#CNRS #Ecotron de MontpellierRésumé
Quantifying intestinal parasite load in freshwater fish requires the development of reliable, minimally invasive methods. We evaluated the use of a very thin and flexible endoscope to detect and quantify acanthocephalan parasites in 25 European chubs (Squalius cephalus). The presence and number of parasites, as estimated using the endoscope, were correlated with dissection-based counts, especially in the anterior part of the intestine accessible via the insertion tube. Accuracy declined in highly infected fish due to overlapping parasites, but endoscopy still provides an accurate evaluation of infection probability and intensity. Thus, this study validates the use of endoscopy as a reliable method for intestinal parasite monitoring in freshwater fish. The deployment of this tool for field-based studies offers promising perspectives for parasitology research.
Auteurs, date et publication :
Auteurs Goutte Aurelie , Ponthus Jean-Pierre , Lorrain Soligon Léa
Publication : Journal of Fish Diseases
Date : 2025
Pages : e70103
Catégorie(s)
#CNRS #ENS #PLANAQUARésumé
Wildfires are one of the main disturbances to vegetation dynamics and the carbon cycle in forest and grassland ecosystems. Wildfires modify the quantity and quality of carbon inputs to the litter and soil. Precise localisation and date of past fires are very useful data in fire studies but historical wildfire archives do not exist for most forests. This lack of data limits our understanding of long-term impacts of wildfires on plant communities and the forest carbon cycle.
Auteurs, date et publication :
Auteurs Maud Chevalier , Samuel Abiven , Johanne Lebrun Thauront
Publication : Fire Ecology
Date : 2025
Volume : 22
Issue : 1
Pages : 3