peer reviewed | Since the dramatic air pollution peaks that prevailed in the course of the 20th century in Europe, effective environmental policies, along with major shifts in fuel usage, resulted in the substantial decrease of SOx and NOx pollution. At the interface between atmosphere and vegetation, epiphytic bryophyte floras responded by massive back-colonisation of formerly polluted areas. Whether extant concentrations of these pollutants are indeed too low to impact species distributions, and whether other pollutants today play a more important role remains, however, an open question. Taking advantage of an air quality monitoring network for a wide range of pollutants in southern Belgium, we implement here variation partitioning and embedded covariate selection to assess the contribution of current air pollutant loads to variations in epiphytic community composition relative to that of background environmental factors. Factors accounting for variation in species composition included, by decreasing order of importance, background environmental factors, major air pollutants (SOx, NOx, O3, fine particle matter), pollutants of agricultural origin (NH3, pesticides), and heavy metals. The substantially larger role played by background environmental factors over air pollution points to the efficiency of air pollution reduction policies, even for such sensitive organisms as epiphytic bryophytes. Ozone was the most important pollutant. Its ecophysiological impact on cryptogamic epiphytes remains poorly known, and the difference of its concentrations between urban and rural areas suggests that it may actually be interpreted as a land-use marker. Pesticides, whose impact on epiphyte floras was not previously assessed, marginally contributed to community composition and species distributions.

International audience | Neonicotinoids are expected to play a significant role in the decline of bird populations through their adverse effects on food resources (primarily insects) and to their lethal and sub-lethal toxicity.Previous studies in the US and the Netherlands have shown links between neonicotinoid use and bird abundance, but the potential for population recovery after ban has not been investigated. Here, we investigated this relationship in France over the 2013 -2022 period, focusing on 57 bird species from insectivorous, granivorous and generalist guilds, surveyed across a large number of plots (n = 1983).We specifically examined imidacloprid, the most widely sold neonicotinoid in France before its ban in 2018, which is still found in surface waters and soils. Additionally, we accounted for potential effects of other pesticides by calculating the Total Applied Toxicity (TAT) for different species groups, as well as landscape and climate factors. We found that population abundance of insectivorous birds was negatively associated with imidacloprid use. We also found that the difference in insectivorous bird abundance between sites with high versus no imidacloprid use was slightly higher before the ban (12.7% more birds in sites with no imidacloprid) than after (9%), suggesting only weak recovery of their populations. In contrast, granivorous and generalist species showed neutral or non-linear associations with other pesticide use and no response to imidacloprid. Our study confirms the detrimental impact of imidacloprid on insectivorous birds and highlights that pesticide bans alone do not ensure immediate biodiversity recovery. This calls for additional conservation actions in landscapes contaminated with neonicotinoids to restore insect and bird populations. | Les néonicotinoïdes devraient jouer un rôle important dans le déclin des populations d'oiseaux en raison de leurs effets néfastes sur les ressources alimentaires (principalement les insectes) et de leur toxicité létale et sublétale. Des études antérieures menées aux États-Unis et aux Pays-Bas ont montré un lien entre l'utilisation des néonicotinoïdes et l'abondance des oiseaux, mais le potentiel de rétablissement des populations après l'interdiction n'a pas été étudié. Nous avons étudié cette relation en France sur la période 2013-2022, en nous concentrant sur 57 espèces d'oiseaux insectivores, granivores et généralistes, recensées sur un grand nombre de parcelles (n = 1983). Nous avons spécifiquement examiné l'imidaclopride, le néonicotinoïde le plus vendu en France avant son interdiction en 2018, qui est toujours présent dans les eaux de surface et les sols. De plus, nous avons pris en compte les effets potentiels d'autres pesticides en calculant la toxicité totale appliquée (TAT) pour différents groupes d'espèces, ainsi que les facteurs liés au paysage et au climat. Nous avons constaté que l'abondance des populations d'oiseaux insectivores était négativement associée à l'utilisation de l'imidaclopride. Nous avons également constaté que la différence d'abondance des oiseaux insectivores entre les sites où l'imidaclopride était largement utilisé et ceux où il ne l'était pas était légèrement plus élevée avant l'interdiction (12,7 % d'oiseaux en plus dans les sites sans imidaclopride) qu'après (9 %), ce qui suggère une faible reprise de leurs populations. En revanche, les espèces granivores et généralistes ont montré des associations neutres ou non linéaires avec l'utilisation d'autres pesticides et aucune réponse à l'imidaclopride. Notre étude confirme l'impact néfaste de l'imidaclopride sur les oiseaux insectivores et souligne que l'interdiction des pesticides ne suffit pas à elle seule à garantir un rétablissement immédiat de la biodiversité. Cela nécessite des mesures de conservation supplémentaires dans les paysages contaminés par les néonicotinoïdes afin de restaurer les populations d'insectes et d'oiseaux.

International audience | Shredder organisms play a key role in rivers by feeding and fragmenting coarse organic matter that will then beexploited by other consumers. The effects of microplastics (MPs) on Gammarus sp., an ubiquitous genus offreshwater amphipods, and its shredding activity have been broadly investigated. However, the potentialbehavioral and physiological effects of different sizes of MPs on Gammarus sp. remain overlooked despite therecognized influence of MP size on MP toxicity. This study investigated the effects of a 28-day exposure to fourdifferent concentrations of two size fractions of PVC-microplastics (PVC-MPs), on Gammarus fossarum mortalityrate, feeding rate, assimilation efficiency, and expression of proteins involved in key processes. Increased mortalitywas observed for all treatments exposed to PVC-MPs, with higher mortality in the presence of smaller PVC-MPs at the highest concentration. No protein biomarker modulation was observed in presence of PVC-MPs,suggesting that no metabolic stress but direct physical damages of PVC-MPs might have led to the observedmortalities. No difference was observed for feeding rates, but a higher assimilation efficiency was measured forindividuals exposed to PVC-MPs, regardless of the concentration. This could be due to energy reallocation towardsdefense mechanisms or indicate a potential shift in digestive microbiota. This study highlighted thetoxicity of PVC-MPs, particularly of smaller sizes and even at relatively low concentration, for Gammarus fossarum.PVC-MP pollution may therefore alter the functional integrity of river ecosystems by reducing theabundance of shredder organisms and, subsequently, the process of leaf litter decomposition.

This study evaluates the degradation and detoxification of okadaic acid (OA), a marine biotoxin, through UV-assisted photochemical processes using environmentally relevant OA concentrations. Experiments were conducted in distilled water (DW) and artificial seawater (ASW), applying two UV sources: UV-LED (λmax = 275 nm) and low-pressure mercury lamp (LP-Hg; λ = 254 nm), combined with hydrogen peroxide (HP), sodium peroxydisulfate (PDS), and potassium peroxymonosulfate (PMS). Photolysis alone was ineffective, and kinetic rate constants (kobs; min−1) followed the trend UV/PMS > UV/PDS > UV/HP for both UV sources. While all treatments showed high OA removal (>79 %) in DW, degradation was significantly reduced for HP (72.8 %–89.9 %) and PDS (67.8 %–76.6 %) in ASW. In contrast, UV/PMS efficacy improved in saline media, achieving rapid and effective degradation of OA, and reaching 99 % detoxification (PP2A activity) within 15 min. The main transformation product, norokadanone (m/z 757.453), formed via decarboxylation, showed significantly reduced toxicity compared to OA. These results confirm the suitability of sulfate radical-based processes (particularly UV/PMS) for OA mitigation in marine environments. In addition, this work highlights the critical role of water matrix composition in marine toxin treatment and supports the development of scalable, mercury-free strategies for effectively mitigating hazardous compounds in coastal environments.

International audience | Tillandsia genus belongs to the Bromeliaceae family plants and some species display active or passive biomonitoring capacities in their natural habitat as it has been described mostly in the American continent. However, Tillandsia aeranthos (Loisiel.) Desf. and Tillandsia bergeri Mez have never been studied for their metal air pollution biomonitor potential. A recent study conducted in our laboratory brought to light the maximum capacity of elements bioconcentration into these two species leaves. The aim of the present study is to determine if T. aeranthos and T. bergeri acclimated to Southern/European region are good biomonitors for airborne elements pollution. Twelve elements were chosen to evaluate the biomonitoring potential (As, Ba, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sn, Ti and Zn). After sampling, the content of the twelve elements in leaves was measured by Inductively Coupled Plasma-Optical Emission Spectrometry and Inductively Coupled Plasma-Mass Spectrometry. Data sets were treated according to sampling sites by box plots over time and Principal Component Analysis. The results showed differences between the two species, with T. bergeri possessing a higher capacity in accumulating elements than T. aeranthos. Fe, Zn and Co showed a higher contribution in the accumulation process in the two Tillandsia species leading to the hypothesis of a good affinity of the two species with these elements. Values obtained for five elements (As, Cr, Ni, Pb and Zn) were compared with values recorded by a monitoring station close to sampling sites showing the efficiency of these two Tillandsia species as biomonitors. High Co accumulation rates obtained in both Tillandsia species were particularly intriguing but could not be rationalized as this metal is not currently monitored by air pollution station in this region. T. aeranthos and T. bergeri proved their efficiency for the biomonitoring of elements air pollution, especially for Co, Fe and Zn.

International audience

International audience | Bisphenol A (BPA) poses longstanding environmental concerns due to its widespread presence and recognized toxicity; however, its multigenerational ecotoxicity, in aquatic models such as water fleas, remains incompletely understood. This study examined the impact of sublethal BPA exposure on Daphnia magna across six generations, tracking changes in both life-history and population traits. Over the first five generations, BPA exposure produced minor and inconsistent effects on age at first oogenesis, age at first offspring production, growth rate, and fertility. The sixth generation exhibited prolonged oogenesis, delayed first offspring production, reduced body size, and decreased fertility, indicating delayed adverse effects. These multigenerational effects did not significantly alter population size or dynamics. Furthermore, BPA exposure did not affect feeding behavior in D. magna over six days, suggesting that food consumption-mediated mechanisms were unlikely a contributing factor. Our findings reveal BPA's delayed adverse effects on D. magna fitness, underscoring potential vulnerabilities for D. magna and other species under additional environmental stressors. These results support literature indicating that endocrine-disrupting chemicals can cause delayed and cumulative adverse effects on zooplankton descendants. Broadening multigenerational research to include a wider range of species, alongside sub-organismal analyses, is crucial to advancing regulatory frameworks and understanding underlying mechanisms.

International audience | Plastic pollution is extremely complex due to the variety of materials resulting from the mixing of synthetic polymers and chemical additives to match their intended applications. Such application-dependent chemical compositions complicate the assessment of plastics' ecotoxicological effects and impacts on biological communities and ecosystem functioning. Our study investigates how plastics affect freshwater microbial community composition and metabolic activity. To that end, we selected eight plastic materials from four polymer types and grouped them by their regulatory classification application ("medical or food grade" vs. "non-medical or food grade") to distinguish material effects from application-dependent chemical composition. After six weeks of biofilm development in three freshwater basins, we analyzed microbial biomass, metabolic functions (photosynthesis, respiration, esterase activity), and algal pigment composition on plastic surfaces and on a chemically inert control. We found that microbial biomass and metabolic activity were more controlled by environmental factors (e.g. suspended solids and light exposure) than by the polymer material and its application, except for esterase activity which was significantly higher in biofilms found on plastics than those found on the control. Algal pigment composition was controlled by both application-dependent plastic composition and environmental conditions. Our study emphasizes the need to consider material properties (e.g. polymer type), intended application (e.g. specific chemical composition) and environmental conditions (e.g. light, suspended solids) to better understand plastic-microbe interactions, which would allow for improved guidance and consequently effective future legislation on polymers and chemical additives.