[Departement_IRSTEA]Ecotechnologies [TR1_IRSTEA]TED [ADD1_IRSTEA]Valoriser les effluents et déchets organiques | International audience | This study provides an alternative solution for the bioremediation of a recalcitrant pharmaceutical micropollutant. Clofibric acid (CLA) was chosen as target molecule, because of its environmental persistence and resistance to wastewater treatment technologies. The aim of this study was to investigate the potential of a phenol-resistant Pseudomonas aeruginosa strain isolated from the activated sludge to degrade CLA. In order to evaluate the effect of acclimation process with glucose as carbon co-substrate, two protocols were performed, in which the transfer of the inoculum is carried out either in the exponential growth phase or in the decline phase. The results showed a removal efficiency of CLA of 35% when cells in the decline phase were used for inoculation. In contrast, a very low removal yield (10%) was achieved when cells harvested in the exponential phase were used as inoculum. This work is the first one reporting on the capability of this bacterium to remove this drug. The obtained data showed that the isolated strain is able to degrade target molecule and might be a promising agent for the elimination of this refractory compound.

This study provides an alternative solution for the bioremediation of a recalcitrant pharmaceutical micropollutant. Clofibric acid (CLA) was chosen as target molecule, because of its environmental persistence and resistance to wastewater treatment technologies. The aim of this study was to investigate the potential of a phenol-resistant Pseudomonas aeruginosa strain isolated from the activated sludge to degrade CLA. In order to evaluate the effect of acclimation process with glucose as carbon co-substrate, two protocols were performed, in which the transfer of the inoculum is carried out either in the exponential growth phase or in the decline phase. The results showed a removal efficiency of CLA of 35% when cells in the decline phase were used for inoculation. In contrast, a very low removal yield (10%) was achieved when cells harvested in the exponential phase were used as inoculum. This work is the first one reporting on the capability of this bacterium to remove this drug. The obtained data showed that the isolated strain is able to degrade target molecule and might be a promising agent for the elimination of this refractory compound.

Biochemical indicators are potent tools to assess ecosystem functioning under anthropic and global pressures. Nevertheless, additional work is needed to improve the methods used for the measurement of these indicators, and for a more relevant interpretation of the obtained results. To face these challenges, the platform Biochem-Env aims at providing innovative and standardized measurement protocols, as well as database and information system favoring result interpretation and opening. Its skills and tools are also offered for expertise, consulting, training, and standardization. In addition, the platform is a service of a French Research Infrastructure for Analysis and Experimentation on Ecosystems, for research in environmental and agricultural sciences.

Biochemical indicators are potent tools to assess ecosystem functioning under anthropic and global pressures. Nevertheless, additional work is needed to improve the methods used for the measurement of these indicators, and for a more relevant interpretation of the obtained results. To face these challenges, the platform Biochem-Env aims at providing innovative and standardized measurement protocols, as well as database and information system favoring result interpretation and opening. Its skills and tools are also offered for expertise, consulting, training, and standardization. In addition, the platform is a service of a French Research Infrastructure for Analysis and Experimentation on Ecosystems, for research in environmental and agricultural sciences.

[Departement_IRSTEA]Eaux [TR1_IRSTEA]QUASARE [ADD1_IRSTEA]Systèmes aquatiques soumis à des pressions multiples | International audience | We used historical sources from the end of the nineteenth to the mid-twentieth century and current data to retrace fish assemblage trajectories for the past 150 years on 29 river stretches distributed throughout the Seine River basin. We based our analyses on species presence/absence, occurrence of amphidromous and non-native species, and species ecological traits related to habitat preference, oxygen and temperature requirements, and diet. In accordance with general trends observed for Western Europe, we detected a general decline of amphidromous species and an increase in nonnative species, even if, at some sites, several non-native species were extirpated. These changes affecting amphidromous and non-native species led to a weak increase in beta-diversity in fish assemblages. Independently of amphidromous and non-native species, for a reduced set of sites, we noted that changes in the balance of ecological traits over time, trace, in a consistent way, the major steps that affected watercourses like waterway development, increasing pollution, dam construction, or, locally, the recent wastewater treatment improvement. Despite local variations, we found contrasted trends between, on one hand, large rivers and/or catchments which had experienced strong expansion in human population, where fish assemblages had deteriorated, and, on the other hand, upstream catchments, with a declining human population, where fish assemblages showed signs of improvement. Because our results suggested that long-term changes affecting fish assemblages cannot be summarized as an unequivocal gradual degradation, we questioned the use of historical data to define ecological reference conditions for river assessment and management purposes.

We used historical sources from the end of the nineteenth to the mid-twentieth century and current data to retrace fish assemblage trajectories for the past 150 years on 29 river stretches distributed throughout the Seine River basin. We based our analyses on species presence/absence, occurrence of amphidromous and non-native species, and species ecological traits related to habitat preference, oxygen and temperature requirements, and diet. In accordance with general trends observed for Western Europe, we detected a general decline of amphidromous species and an increase in non-native species, even if, at some sites, several non-native species were extirpated. These changes affecting amphidromous and non-native species led to a weak increase in beta-diversity in fish assemblages. Independently of amphidromous and non-native species, for a reduced set of sites, we noted that changes in the balance of ecological traits over time, trace, in a consistent way, the major steps that affected watercourses like waterway development, increasing pollution, dam construction, or, locally, the recent wastewater treatment improvement. Despite local variations, we found contrasted trends between, on one hand, large rivers and/or catchments which had experienced strong expansion in human population, where fish assemblages had deteriorated, and, on the other hand, upstream catchments, with a declining human population, where fish assemblages showed signs of improvement. Because our results suggested that long-term changes affecting fish assemblages cannot be summarized as an unequivocal gradual degradation, we questioned the use of historical data to define ecological reference conditions for river assessment and management purposes.

International audience

The rhizosphere hosts a considerable microbial community. Among that community, bacteria called plant growth-promoting rhizobacteria (PGPR) can promote plant growth and defense against diseases using diverse distinct plant-beneficial functions. Crop inoculation with PGPR could allow to reduce the use of pesticides and fertilizers in agrosystems. However, microbial crop protection and growth stimulation would be more efficient if cooperation between rhizosphere bacterial populations was taken into account when developing biocontrol agents and biostimulants. Rhizospheric bacteria live in multi-species biofilms formed all along the root surface or sometimes inside the plants (i.e., endophyte). PGPR cooperate with their host plants and also with other microbial populations inside biofilms. These interactions are mediated by a large diversity of microbial metabolites and physical signals that trigger cell–cell communication and appropriate responses. A better understanding of bacterial behavior and microbial cooperation in the rhizosphere could allow for a more successful use of bacteria in sustainable agriculture. This review presents an ecological view of microbial cooperation in agrosystems and lays the emphasis on the main microbial metabolites involved in microbial cooperation, plant health protection, and plant growth stimulation. Eco-friendly inoculant consortia that will foster microbe–microbe and microbe–plant cooperation can be developed to promote crop growth and restore biodiversity and functions lost in agrosystems.

The applicability of radon (222Rn) measurements to delineate non-aqueous phase liquids (NAPL) contamination in subsoil is discussed at a site with lithological discontinuities through a blind test. Three alpha spectroscopy monitors were used to measure radon in soil air in a 25,000-m2 area, following a regular sampling design with a 20-m2 grid. Repeatability and reproducibility of the results were assessed by means of duplicate measurements in six sampling positions. Furthermore, three points not affected by oil spills were sampled to estimate radon background concentration in soil air. Data histograms, Q-Q plots, variograms, and cluster analysis allowed to recognize two data populations, associated with the possible path of a fault and a lithological discontinuity. Even though the concentration of radon in soil air was dominated by this discontinuity, the characterization of the background emanation in each lithological unit allowed to distinguish areas potentially affected by NAPL, thus justifying the application of radon emanometry as a screening technique for the delineation of NAPL plumes in sites with lithological discontinuities.

The applicability of radon (²²²Rn) measurements to delineate non-aqueous phase liquids (NAPL) contamination in subsoil is discussed at a site with lithological discontinuities through a blind test. Three alpha spectroscopy monitors were used to measure radon in soil air in a 25,000-m² area, following a regular sampling design with a 20-m² grid. Repeatability and reproducibility of the results were assessed by means of duplicate measurements in six sampling positions. Furthermore, three points not affected by oil spills were sampled to estimate radon background concentration in soil air. Data histograms, Q-Q plots, variograms, and cluster analysis allowed to recognize two data populations, associated with the possible path of a fault and a lithological discontinuity. Even though the concentration of radon in soil air was dominated by this discontinuity, the characterization of the background emanation in each lithological unit allowed to distinguish areas potentially affected by NAPL, thus justifying the application of radon emanometry as a screening technique for the delineation of NAPL plumes in sites with lithological discontinuities.

International audience | Mercury (Hg) is a toxic contaminant present in most aquatic ecosystems. High concentrations pose serious threats to organisms and to human health. Because previous studies focused on few countries, environmental hazard due to Hg contamination remains obscure in many geographic areas, and for example limited information is available in North Africa. We examined total Hg contamination in 13 sites in Morocco (12 rivers and one lake) spread over a large area, 400 km north–south and 350 km west–east, that encompasses different biogeographic zones separated by the Atlas Mountains. Due to their longevity and sedentary habits, we used freshwater turtles as biological probes to monitor Hg exposure. Keratinized tissues reflect long-term Hg exposure; thus, we assayed Hg concentration in the claws of > 200 individuals and supplemented these data with blood Hg concentrations of > 60 individuals (a tissue that provides shorter term Hg exposure integration). The results provide the first large-scale picture of Hg contamination in the aquatic freshwater systems of Morocco. Comparisons with previous studies revealed that some of the sites were highly contaminated (e.g. mean Hg concentrations were above 5 μg g⁻¹, a very high level in keratinized tissues) whereas other sites presented moderate or baseline levels. Unexpectedly, all highly contaminated sites were found in less densely populated areas, while more densely urbanized northern sites, even the sewers of large cities, were not highly contaminated. We hypothesize that silver mining activities in the southern High Atlas and in the Anti-Atlas contaminate rivers of the catchment basins over long distances. These findings indicate that fish, water consumption and contamination levels in local people should be further scrutinized.

Mercury (Hg) is a toxic contaminant present in most aquatic ecosystems. High concentrations pose serious threats to organisms and to human health. Because previous studies focused on few countries, environmental hazard due to Hg contamination remains obscure in many geographic areas, and for example limited information is available in North Africa. We examined total Hg contamination in 13 sites in Morocco (12 rivers and one lake) spread over a large area, 400 km north–south and 350 km west–east, that encompasses different biogeographic zones separated by the Atlas Mountains. Due to their longevity and sedentary habits, we used freshwater turtles as biological probes to monitor Hg exposure. Keratinized tissues reflect long-term Hg exposure; thus, we assayed Hg concentration in the claws of > 200 individuals and supplemented these data with blood Hg concentrations of > 60 individuals (a tissue that provides shorter term Hg exposure integration). The results provide the first large-scale picture of Hg contamination in the aquatic freshwater systems of Morocco. Comparisons with previous studies revealed that some of the sites were highly contaminated (e.g. mean Hg concentrations were above 5 μg g⁻¹, a very high level in keratinized tissues) whereas other sites presented moderate or baseline levels. Unexpectedly, all highly contaminated sites were found in less densely populated areas, while more densely urbanized northern sites, even the sewers of large cities, were not highly contaminated. We hypothesize that silver mining activities in the southern High Atlas and in the Anti-Atlas contaminate rivers of the catchment basins over long distances. These findings indicate that fish, water consumption and contamination levels in local people should be further scrutinized.

Ecotoxicological tests with earthworms are widely used and are mandatory for the risk assessment of pesticides prior to registration and commercial use. The current model species for standardized tests is Eisenia fetida or Eisenia andrei. However, these species are absent from agricultural soils and often less sensitive to pesticides than other earthworm species found in mineral soils. To move towards a better assessment of pesticide effects on non-target organisms, there is a need to perform a posteriori tests using relevant species. The endogeic species Aporrectodea caliginosa (Savigny, 1826) is representative of cultivated fields in temperate regions and is suggested as a relevant model test species. After providing information on its taxonomy, biology, and ecology, we reviewed current knowledge concerning its sensitivity towards pesticides. Moreover, we highlighted research gaps and promising perspectives. Finally, advice and recommendations are given for the establishment of laboratory cultures and experiments using this soil-dwelling earthworm species.

Ecotoxicological tests with earthworms are widely used and are mandatory for the risk assessment of pesticides prior to registration and commercial use. The current model species for standardized tests is Eisenia fetida or Eisenia andrei. However, these species are absent from agricultural soils and often less sensitive to pesticides than other earthworm species found in mineral soils. To move towards a better assessment of pesticide effects on non-target organisms, there is a need to performaposterioritestsusingrelevantspecies.TheendogeicspeciesAporrectodeacaliginosa(Savigny,1826)isrepresentative of cultivated fields in temperate regions and is suggested as a relevant model test species. After providing information on its taxonomy, biology, and ecology, we reviewed current knowledge concerning its sensitivity towards pesticides. Moreover, we highlighted research gaps and promising perspectives. Finally, advice and recommendations are given for the establishment of laboratory cultures and experiments using this soil-dwelling earthworm species.