International audience | Prolonged exposure to low levels of dietary contaminants is a context in modern life that could alter organ physiology gradually. Here, we aimed to investigate the impact of continuous exposure to acceptable daily intake (ADI) and non-observable adverse effect level (NOAEL) of glyphosate from gestation to adulthood using C57BL/6J mice and incorporating these levels into their food pellets. From adulthood, we analyzed neurophysiological and neuro-glia cellular adaptations in male and female animals. Using ex-vivo hippocampal slice electrophysiology, we found a reduced efficacy of Schaffer collateral-to-CA1 excitatory synapses in glyphosate-exposed dietary conditions, with ADI and NOAEL dose-dependent effects. Short-term facilitation of excitatory synaptic transmission was specifically increased in NOAEL conditions, with a predominant influence in males, suggesting a reduced probability of neurotransmitter release. Long-term synaptic potentiation (LTP) was decreased in NOAEL-exposed mice. Next, we explore whether these neurophysiological modifications are associated with neuro-glia changes in the somatosensory cortex and hippocampus. High-resolution confocal microscopy analyses unveil a dose-dependent increased density of excitatory Vglut1+ Homer1+ synapses. Microglial Iba1+ cells displayed a shortening of their ramifications, a sign of cellular reactivity that was more pronounced in males at NOAEL levels. The morphology of GFAP+ astrocytes was generally not modified. Finally, we asked whether mouse-specific cross-correlations exist among all data sets generated. This examination included the novel object recognition (NOR) test performed before ex vivo functional and immunohistochemical examinations. We report a negative linear regression between the number of synapses and NOR or LTP maintenance when plotting ADI and NOAEL datasets. These results outline synaptic and microglial cell adaptations resulting from prenatal and continuous dietary low levels of glyphosate, discernible in, but not limited to, adult males exposed to the NOAEL. We discuss the significance of these findings to real-world consumer situations and long-term brain resilience.

International audience | Micro- and nanoplastics (MNP) have recently received particular attention in freshwater and marine ecosystems, but less is known about their impact on terrestrial species. Ants can be used as biological indicators for many types of pollutants and are therefore a good candidate to explore the effects of MNP pollution. In the present study, we investigated the ability of workers from seven colonies of the acrobat ant Crematogaster scutellaris to detect MNP in their food. After two days of starvation, groups of ten ants were tested for their preference toward control and polyethylene-treated solutions. Every 5 min over a total 20 min period, the number of workers feeding on either solution was counted. The results showed that C. scutellaris workers could detect and avoid contaminated food, feeding more often on the uncontaminated solution in the first 10 min. However, after 10 min the food preference was no longer significant between the groups, likely owing to feeding satiation. We then assessed whether this feeding behaviour is sufficient to cause the accumulation of MNP in the ant. We thereby provided a solution containing fluorescent MNP (fMNP) at the same concentration as in the previous experiments. Observation of the ants' mouthparts using fluorescent light microscopy showed that after 10 min dense aggregations of fMNP were visible. Further investigations are needed to understand the mechanisms of detection of MNP by ants, and the accumulation dynamics in ants' bodies. Moreover, the effects of MNP on the integrity and fitness of ant colonies, as well as the potential transfer across terrestrial trophic chains should be explored.

International audience | This paper presents a new Remote Hyperspectral Imaging System (RHIS) embedded on an Unmanned Aquatic Drone (UAD) for plastic detection and identification in coastal and freshwater environments. This original system, namely the Remotely Operated Vehicle of the University of Littoral Côte d’Opale (ROV-ULCO), works in a near-field of view, where the distance between the hyperspectral camera and the water surface is about 45 cm. In this paper, the new ROV-ULCO system with all its components is firstly presented. Then, a hyperspectral image database of plastic litter acquired with this system is described. This database contains hyperspectral data cubes of different plastic types and polymers corresponding to the most-common plastic litter items found in aquatic environments. An in situ spectral analysis was conducted from this benchmark database to characterize the hyperspectral reflectance of these items in order to identify the absorption feature wavelengths for each type of plastic. Finally, the ability of our original system RHIS to automatically recognize different types of plastic litter was assessed by applying different supervised machine learning methods on a set of representative image patches of marine litter. The obtained results highlighted the plastic litter classification capability with an overall accuracy close to 90%. This paper showed that the newly presented RHIS coupled with the UAD is a promising approach to identify plastic waste in aquatic environments.

International audience | Analyzing the environmental factors affecting benthic communities in coastal areas is crucial for uncovering key factors that require conservation action. Here, we collected benthic and environmental (physical-chemical-historical and land-based) data for 433 transects in Taiwan. Using a k-means approach, five communities dominated by crustose coralline algae, turfs, stony corals, digitate, or bushy octocorals were first delineated. Conditional random forest models then identified physical, chemical, and land-based factors (e.g., light intensity, nitrite, and population density) relevant to community delineation and occurrence. Historical factors, including typhoons and temperature anomalies, had only little effect. The prevalent turf community correlated positively with chemical and land-based drivers, which suggests that anthropogenic impacts are causing a benthic homogenization. This mechanism may mask the effects of climate disturbances and regional differentiation of benthic assemblages. Consequently, management of nutrient enrichment and terrestrial runoff is urgently needed to improve community resilience in Taiwan amidst increasing challenges of climate change.

International audience | Tracking PFAS in ecosystems is challenging. In this context, monitoring programs are crucial to fill data gaps, especially in marine environments, which are the ultimate outlets for these forever chemicals. The 2021 chemical contamination monitoring campaign along the French Mediterranean coast established a baseline for PFAS concentrations in mussels, with 90 % of measurements below quantification limits. When detected, long-chain PFCA's were predominant. Spatial distribution patterns suggested continuous PFAS inputs and complex dynamics, shaped by the influence of large watersheds and rivers (Rhône, Aude, Huveaune). Lapeyrade shallow lagoon stood out as the most contaminated site. Similar PFAS profiles in connected sites implied shared sources but raised questions about accumulation processes in mussels. While certain sites had evident sources (e.g., military airbase for Palo lagoon), others remained uncertain (e.g., Toulon bay). Coastal stations (Banyuls, Cap Agde, Brégançon, Pampelonne) showed PFAS contamination without clear onshore sources, possibly due to insufficient transportation process understanding.

International audience | The hydro-meteorological conditions in marine environments are recognized to have a major impact on the transport and dispersion of microplastics (MP), although their precise effects remain poorly understood. This study investigates the effects of tidal fluctuations on MP abundance and composition in a megatidal coastal water. Waters samples were collected every ninety minutes over the course of two complete tidal cycles – one during spring tide and another during neap tide. There were no significant disparities in term of abondance, size, and composition of MPs between the samples collected during the two tidal cycles. Nevertheless, MP abundance and characteristics (morphology, size and polymer types) can be influenced over the course of a complete tidal cycle due to the impact of tidal currents and water height. This study highlights the need to consider the fluctuations of the tidal cycle when planning in-situ surveys to better assess MP pollution in coastal environments.

The application of plant protection products (PPPs) may have delayed and long-term non-intentional impacts on aquatic invertebrates inhabiting agricultural landscapes. Such effects may induce population responses based on developmental and transgenerational plasticity, selection of genetic resistance, as well as increased extirpation risks associated with random genetic drift. While the current knowledge on such effects of PPPs is still scarce in non-target aquatic invertebrate species, evidences are accumulating that support the need for consideration of evolutionary components of the population response to PPPs in standard procedures of risk assessment. This mini-review, as part of a contribution to the collective scientific assessment on PPP impacts on biodiversity and ecosystem services performed in the period 2020–2022, presents a brief survey of the current results published on the subject, mainly in freshwater crustaceans, and proposes some research avenues and strategies that we feel relevant to fill this gap.

International audience | On September 26th 2019, a major fire occurred in the Lubrizol factory located near the Seine estuary, in RouenFrance. Juvenile flounders were captured in the Canche estuary (a reference system) and caged one month in the Canche and in the Seine downstream the accident site. No significant increases of PAHs, PCBs and PFAS was detected in Seine vs Canche sediments after the accident, but a significant increase of dioxins and furans was observed in water and sewage sludge in the Rouen wastewater treatment plant. The proteomics approach highlighted a dysregulation of proteins associated with cholesterol synthesis and lipid metabolism, in fish caged in the Seine. The overall results suggested that the fire produced air borne dioxins and furans that got deposited on soil and subsequently entered in the Seine estuarine waters via runoff; thus contaminating fish preys and caged flounders in the Seine estuary.

International audience | Plant protection products (PPP) are extensively used to protect plants against harmful organisms, but they also have unintended effects on non-target organisms, especially terrestrial invertebrates. The impact of PPP on ecosystem functions provided by these non-target invertebrates remains, however, unclear. The objectives of this article were to review PPP impacts on the ecosystem functions provided by pollinators, predators and parasitoids, and soil organisms; and to identify the factors that aggravate or mitigate PPP effects. The literature highlights that PPP alter several ecosystem functions: provision and maintenance of biodiversity, pollination, biotic interactions and habitat completeness in terrestrial ecosystems, and organic matter and soil structure dynamics. However, there are still a few studies dealing with ecosystem functions, with sometimes contradictory results, and consequences on agricultural provisioning services remain unclear. The model organisms used to assess PPP ecotoxicological effects are still limited, and should be expanded to better cover the wide functional diversity of terrestrial invertebrates. Data are lacking on PPP sublethal, transgenerational and “cocktail” effects, and on their multitrophic consequences. In empirical assessments, studies on PPP unintended effects should consider agricultural-pedoclimatic contexts because they influence the responses of non-target organisms and associated ecosystem functions to PPP. Modeling might be a promising way to account for the complex interactions among PPP mixtures, biodiversity and ecosystem functioning.

International audience | Copper-based plant protection products (PPPs) are widely used in both conventional and organic farming, and to a lesser extent for non-agricultural maintenance of gardens, greenspaces, and infrastructures. The use of copper PPPs adds to environmental contamination by this trace element. This paper aims to review the contribution of these PPPs to the contamination of soils and waters by copper in the context of France (which can be extrapolated to most of the European countries), and the resulting impacts on terrestrial and aquatic biodiversity, as well as on ecosystem functions. It was produced in the framework of a collective scientific assessment on the impacts of PPPs on biodiversity and ecosystem services in France. Current science shows that copper, which persists in soils, can partially transfer to adjacent aquatic environments (surface water and sediment) and ultimately to the marine environment. This widespread contamination impacts biodiversity and ecosystem functions, chiefly through its effects on phototrophic and heterotrophic microbial communities, and terrestrial and aquatic invertebrates. Its effects on other biological groups and biotic interactions remain relatively under-documented.