peer reviewed | A N-15 tracer study was performed during an experimental transplantation trial of natural Posidonia oceanica cuttings. The experiment was done in situ at 17 m depth in the Revellata Bay (Calvi, NW Corsica, France). Despite high survival rates of transplants (>90%) after one year, the weight and the N content of transplants are significantly lower than those of reference plants. In absence of roots, the transplants are not able to meet their N requirement because, leaf uptake is insufficient to replenish the N lost during the natural leaf decay. This could constitute a major cause of long-term failure for transplantation experiments or natural recolonisation processes. The increase of the N-15 content in the roots shows that the plant re-allocates the nitrogen of one organ (i.e. leaves, rhizomes) to ensure the growth of another (i.e. roots). (C) 2003 Elsevier Ltd. All rights reserved. | Novel Marine Technology (NOMATEC)

Les émissions d'ammoniac vers l'atmosphère, consécutives aux épandages de lisiers de porcs, ont été quanitifiées à l'aide de tunnels de ventilation. Ces appareils permettent la circulation de l'air en surface de la micro-parcelle expérimentale (1m2) qui reçoit l'apport de lisier. L'échantillonnage de l'air en sortie du tunnel (piégeage dans une solution acide) permet de quantifier l'ammoniac qui se dégage. Plusieurs essais, réalisés dans les quatre départements bretons au cours de l'année 1993, ont permis de mettre en évidence des pertes d'ammoniac allant de 5 à 63% de l'azote ammoniacal apporté par le lisier. Les résultats témoignent également de l'importance et de la rapidité du processus dans les premières heures qui suivent l'épandage : 72% des pertes totales mesurées ont eu lieu durant les 12 premières heures. Les émissions d'ammoniac sur ces 12 premières heures étaient notamment corrélées à la température (r=0,790) et à la dose d'azote ammoniacal apportée (kg N-NH4+/ha) (r=0,762). Afin d'envisager des voies de réduction de ce type d'émissions gazeuses, des essais réalisés au laboratoire en cellule de mesure ont été mis en place. L'acidifiction préalable du lisier à pH 6,5 (ajout d'HCL 10N) ainsi que l'ajout de chlorure de calcium (CaCl2,2H20) à hauteur de 92 g/l ont permis de réduire le processus de volatilisation d'ammoniac de 85% environ. | Ammonia emissions from surface-applied pig and cattle slurry were measured using a system of win tunnels. Field experiments carried out in Brittany (west of France) in 1993, shows ammonia losses ranging from 5 to 63% of the total ammoniacal nitrogen applied. On average 72% of the total losses occured within the first 12 hours after spreading. During this period, ammonia losses are closely correlated with temperature and the nitrogen rate applied. Laboratory experiments demonstrate the effects of the acidification and addition of calcium chloride (Cacl2,2H20) to the slurry which allows a 85% reduction of ammonia loss.

Proceedings of the 2nd International Conference on Microplastic Pollution in the Mediterranean Sea, Capri, ITALIE, 15-/09/2019 - 18/09/2019 | International audience | Nowadays, microplastic (MPs) pollution is well documented in marine ecosystems since the first publication alarming about marine plastic pollution in 1972 [1]. Similarly, continental contamination is more and more investigated. More recently, interest for estuarine systems is growing. Estuaries are considered as a suspected predominant pathway for microplastic pollution from continent to oceans. The specific conditions of estuaries, like salinity gradient, tides and hydrodynamics, could affect the repartition, settling and transfer of microplastics to marine systems.

International audience | Mining areas and in particular those containing massive sulfides have left a heavy environmental legacy with soils and hydrographic networks highly contaminated with metals and metalloids as for example in the Iberian Pyrite Belt (Huelva, Spain). Here, we present new data on copper (Cu) isotopic composition of waters and solids collected along a continuum Mine (Tharsis)-River (Meca)-Lake (Sancho) in the Iberian Pyrite Belt. Our results show that the isotopic signature of pit lakes is spatially variable, but remains stable over the seasons; this signature seems to be controlled by water-rock interaction processes. The data obtained on the Meca River imply a number of attenuation processes such as decrease in the metal concentration by precipitation of secondary minerals. This is accompanied by preferential retention of the heavy isotope (Cu-65) with a possibility of living organisms (e.g., algae) participation. The terminal Sancho lake demonstrated constant isotopic signature over the entire depth of the water column despite sizable variations in Cu concentrations, which can be tentatively explained by a superposition of counter-interacting biotic and abiotic processes of Cu fractionation. Overall, the understanding of the isotopic variations along the hydrological continuum is useful for a better understanding of metal element transfer within mining environments and surrounding surface waters.

International audience | Triazoles belong to a family of fungicides that are ubiquitous in agroecosystems due to their widespread use in crops. Despite their efficiency in controlling fungal diseases, triazoles are also suspected to affect non-target vertebrate species through the disruption of key physiological mechanisms. Most studies so far have focused on aquatic animal models, and the potential impact of triazoles on terrestrial vertebrates has been overlooked despite their relevance as sentinel species of contaminated agroecosystems. Here, we examined the impact of tebuconazole on the thyroid endocrine axis, associated phenotypic traits (plumage quality and body condition) and sperm quality in wild-caught house sparrows (Passer domesticus). We experimentally exposed house sparrows to realistic concentrations of tebuconazole under controlled conditions and tested the impact of this exposure on the levels of thyroid hormones (T3 and T4), feather quality (size and density), body condition and sperm morphology. We found that exposure to tebuconazole caused a significant decrease in T4 levels, suggesting that this azole affects the thyroid endocrine axis, although T3 levels did not differ between control and exposed sparrows. Importantly, we also found that exposed females had an altered plumage structure (larger but less dense feathers) relative to control females. The impact of tebuconazole on body condition was dependent on the duration of exposure and the sex of individuals. Finally, we did not show any effect of exposure to tebuconazole on sperm morphology. Our study demonstrates for the first time that exposure to tebuconazole can alter the thyroid axis of wild birds, impact their plumage quality and potentially affect their body condition. Further endocrine and transcriptomic studies are now needed not only to understand the underlying mechanistic effects of tebuconazole on these variables, but also to further investigate their ultimate consequences on performance (i.e. reproduction and survival).

International audience | Neonicotinoids are the most widely used class of insecticides in the world but they have raised numerous concerns regarding their effects on biodiversity. Thus, the objective of this work was to do a critical review of the contamination of the environment (soil, water, air, biota) by neonicotinoids (acetamiprid, clothianidin, imidacloprid, thiacloprid, thiamethoxam) and of their impacts on terrestrial and aquatic biodiversity. Neonicotinoids are very frequently detected in soils and in freshwater, and they are also found in the air. They have only been recently monitored in coastal and marine environments, but some studies already reported the presence of imidacloprid and thiamethoxam in transitional or semi-enclosed ecosystems (lagoons, bays and estuaries). The contamination of the environment leads to the exposure and to the contamination of non-target organisms, and to negative effects on biodiversity. Direct impacts of neonicotinoids are mainly reported on terrestrial invertebrates (e.g., pollinators, natural enemies, earthworms) and vertebrates (e.g., birds), and on aquatic invertebrates (e.g., arthropods). Impacts on aquatic vertebrate populations and communities, as well as on microorganisms, are less documented. In addition to their toxicity to directly exposed organisms, neonicotinoid induce indirect effects via trophic cascades as demonstrated in several species (terrestrial and aquatic invertebrates). However, more data are needed to reach firmer conclusions and to get a clearer picture of such indirect effects. Finally, we identified specific knowledge gaps that need to be filled to better understand the effects of neonicotinoids on terrestrial, freshwater and marine organisms, as well as on ecosystem services associated with these biotas.

International audience | The adverse outcome pathway (AOP) has been conceptualized in 2010 as an analytical construct to describe a sequential chain of causal links between key events, from a molecular initiating event leading to an adverse outcome (AO), considering several levels of biological organization. An AOP aims to identify and organize available knowledge about toxic effects of chemicals and drugs, either in ecotoxicology or toxicology, and it can be helpful in both basic and applied research and serve as a decision-making tool in support of regulatory risk assessment. The AOP concept has evolved since its introduction, and recent research in toxicology, based on integrative systems biology and artificial intelligence, gave it a new dimension. This innovative in silico strategy can help to decipher mechanisms of action and AOP and offers new perspectives in AOP development. However, to date, this strategy has not yet been applied to ecotoxicology. In this context, the main objective of this short article is to discuss the relevance and feasibility of transferring this strategy to ecotoxicology. One of the challenges to be discussed is the level of organisation that is relevant to address for the AO (population/community). This strategy also offers many advantages that could be fruitful in ecotoxicology and overcome the lack of time, such as the rapid identification of data available at a time t, or the identification of “data gaps”. Finally, this article proposes a step forward with suggested priority topics in ecotoxicology that could benefit from this strategy.

International audience | Rivers are representative of the overall contamination found in their catchment area. Contaminant concentrations in watercourses depend on numerous factors including land use and rainfall events. Globally, in Mediterranean regions, rainstorms are at the origin of fluvial multipollution phenomena as a result of Combined Sewer Overflows (CSOs) and floods. Large loads of urban-associated microorganisms, including faecal bacteria, are released from CSOs which place public health - as well as ecosystems - at risk. The impacts of freshwater contamination on river ecosystems have not yet been adequately addressed, as is the case for the release of pollutant mixtures linked to extreme weather events. In this context, microbial communities provide critical ecosystem services as they are the only biological compartment capable of degrading or transforming pollutants. Through the use of 16S rRNA gene metabarcoding of environmental DNA at different seasons and during a flood event in a typical Mediterranean coastal river, we show that the impacts of multipollution phenomena on structural shifts in the particle-attached riverine bacteriome were greater than those of seasonality. Key players were identified via multivariate statistical modelling combined with network module eigengene analysis. These included species highly resistant to pollutants as well as pathogens. Their rapid response to contaminant mixtures makes them ideal candidates as potential early biosignatures of multipollution stress. Multiple resistance gene transfer is likely enhanced with drastic consequences for the environment and human-health, particularly in a scenario of intensification of extreme hydrological events.