International audience | Polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) are persistent organic pollutants (POPs) that are present as complex mixtures in all environmental compartments, including aquatic ecosystems. However, little is known about the effects of such complex mixtures on teleost behaviour. In this study, zebrafish (Danio rerio) were chronically exposed to an environmentally relevant mixture (MIX) containing 22 PCB and 7 PBDE congeners through diet from 5 days post fertilization onwards. MIX-exposed F0 fish produced offspring (F1 and F2 generations) that were fed using plain food and grown until adulthood. In each generation, five behavioural traits (i.e. boldness, activity, sociality, exploration and anxiety) were evaluated by the mean of different experimental set-ups. Two distinct behavioural syndromes were identified: boldness, positively correlated to activity and exploration; and anxiety, associated with low sociality. F0 fish did not display any behavioural disruption resulting from POP exposure whereas F1 MIX fish were bolder than fish from other generations but did not differ significantly from F1 controls. F2 MIX fish displayed a higher anxiety syndrome than F2 controls. This is of particular importance since such behavioural changes in offspring generations may have persistent ecological consequences, may affect fitness and hence cause detrimental effects on wild fish populations exposed to POP mixtures.

Polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) are persistent organic pollutants (POPs) that are present as complex mixtures in all environmental compartments, including aquatic ecosystems. However, little is known about the effects of such complex mixtures on teleost behaviour. In this study, zebrafish (Danio rerio) were chronically exposed to an environmentally relevant mixture (MIX) containing 22 PCB and 7 PBDE congeners through diet from 5 days post fertilization onwards. MIX-exposed F0 fish produced offspring (F1 and F2 generations) that were fed using plain food and grown until adulthood. In each generation, five behavioural traits (i.e. boldness, activity, sociality, exploration and anxiety) were evaluated by the mean of different experimental set-ups. Two distinct behavioural syndromes were identified: boldness, positively correlated to activity and exploration; and anxiety, associated with low sociality. F0 fish did not display any behavioural disruption resulting from POP exposure whereas F1 MIX fish were bolder than fish from other generations but did not differ significantly from F1 controls. F2 MIX fish displayed a higher anxiety syndrome than F2 controls. This is of particular importance since such behavioural changes in offspring generations may have persistent ecological consequences, may affect fitness and hence cause detrimental effects on wild fish populations exposed to POP mixtures.

International audience | While long-term organic fertilizer (OF) applications tend to decrease copper (Cu) and zinc (Zn) availability in agricultural soils, earthworm bioturbation has been reported to have the opposite effect. Thus, the consequences of OF amendments in earthworm-inhabited soils on Cu and Zn bioavailability to earthworms are still under debate. Here, we assessed the effect of a decade of agronomically realistic OF applications on Cu and Zn availability in earthworm-inhabited soils and the consequences on Cu and Zn bioavailability to earthworms. An epi-endogeic species (Dichogaster saliens) was exposed in microcosms to three field-collected soils that had received either no, mineral, or organic fertilization for a decade. Dissolved organic matter (DOM) properties (i.e., concentration, aromaticity, and binding properties toward Cu), pH, and Cu and Zn availability (i.e., total concentration and free ionic activity) were determined in the solution of the soil containing earthworms. Cu and Zn bioavailability was assessed by measuring the net accumulation (ng) and concentration of Cu and Zn in earthworms (mg kg(-1)). Despite soil Cu and Zn contamination induced by a decade of OF applications, organic fertilization induced an increase in soil pH and DOM properties that drove the reduction of Cu and Zn availability in earthworm-inhabited soils, while bioturbation had little effect on soil pH, DOM properties, and Cu and Zn availability. Consistently, Cu and Zn bioavailability to earthworms did not increase with OF applications. From an ecotoxicological perspective, our results suggest that agronomically realistic applications of OF for a decade should not pose a risk to earthworms in terms of Cu and Zn net accumulation, but further studies have to be undertaken to understand consequent long-term toxicity after exposure.

While long-term organic fertilizer (OF) applications tend to decrease copper (Cu) and zinc (Zn) availability in agricultural soils, earthworm bioturbation has been reported to have the opposite effect. Thus, the consequences of OF amendments in earthworm-inhabited soils on Cu and Zn bioavailability to earthworms are still under debate. Here, we assessed the effect of a decade of agronomically realistic OF applications on Cu and Zn availability in earthworm-inhabited soils and the consequences on Cu and Zn bioavailability to earthworms. An epi-endogeic species (Dichogaster saliens) was exposed in microcosms to three field-collected soils that had received either no, mineral, or organic fertilization for a decade. Dissolved organic matter (DOM) properties (i.e., concentration, aromaticity, and binding properties toward Cu), pH, and Cu and Zn availability (i.e., total concentration and free ionic activity) were determined in the solution of the soil containing earthworms. Cu and Zn bioavailability was assessed by measuring the net accumulation (ng) and concentration of Cu and Zn in earthworms (mg kg−1). Despite soil Cu and Zn contamination induced by a decade of OF applications, organic fertilization induced an increase in soil pH and DOM properties that drove the reduction of Cu and Zn availability in earthworm-inhabited soils, while bioturbation had little effect on soil pH, DOM properties, and Cu and Zn availability. Consistently, Cu and Zn bioavailability to earthworms did not increase with OF applications. From an ecotoxicological perspective, our results suggest that agronomically realistic applications of OF for a decade should not pose a risk to earthworms in terms of Cu and Zn net accumulation, but further studies have to be undertaken to understand consequent long-term toxicity after exposure.

International audience | In 2020 two main French research institutes, INRA and IRSTEA, merged to form INRAE the French National Research Institute for Agriculture, Food and Environment. This was a timely opportunity to update the ecotoxicology delineations and to identify new key issues to be developedat INRAE, notably by including aquatic ecosystems biodiversity and public policies as new research priorities, and for the French ECOTOX Network of terrestrial and aquatic ecotoxicology supported by INRAE (https://www6.inrae.fr/ecotox/) to address new research and development topics.Within this context, the ecotoxicology of the soil:water continuum (SWC) was chosen as the theme of the 7th seminar of the ECOTOX Network held as a 2-day webinar in November 2020. This special issue proposes a selection of some of the presented studies, covering subjects from terrestrial to aquatic ecotoxicology, including experimental and modelling approaches, to finally tentatively describe what could stand for SWC ecotoxicology in the Anthropocene context.

International audience | In 2020 two main French research institutes, INRA and IRSTEA, merged to form INRAE the French National Research Institute for Agriculture, Food and Environment. This was a timely opportunity to update the ecotoxicology delineations and to identify new key issues to be developedat INRAE, notably by including aquatic ecosystems biodiversity and public policies as new research priorities, and for the French ECOTOX Network of terrestrial and aquatic ecotoxicology supported by INRAE (https://www6.inrae.fr/ecotox/) to address new research and development topics.Within this context, the ecotoxicology of the soil:water continuum (SWC) was chosen as the theme of the 7th seminar of the ECOTOX Network held as a 2-day webinar in November 2020. This special issue proposes a selection of some of the presented studies, covering subjects from terrestrial to aquatic ecotoxicology, including experimental and modelling approaches, to finally tentatively describe what could stand for SWC ecotoxicology in the Anthropocene context.

International audience | In 2020 two main French research institutes, INRA and IRSTEA, merged to form INRAE the French National Research Institute for Agriculture, Food and Environment. This was a timely opportunity to update the ecotoxicology delineations and to identify new key issues to be developedat INRAE, notably by including aquatic ecosystems biodiversity and public policies as new research priorities, and for the French ECOTOX Network of terrestrial and aquatic ecotoxicology supported by INRAE (https://www6.inrae.fr/ecotox/) to address new research and development topics.Within this context, the ecotoxicology of the soil:water continuum (SWC) was chosen as the theme of the 7th seminar of the ECOTOX Network held as a 2-day webinar in November 2020. This special issue proposes a selection of some of the presented studies, covering subjects from terrestrial to aquatic ecotoxicology, including experimental and modelling approaches, to finally tentatively describe what could stand for SWC ecotoxicology in the Anthropocene context.

International audience | The evaluation of soil quality requires the use of robust methods to assess biologically based indicators. Among them, enzyme activities are used for several decades, but there is a clear need to update their measurement methods for routine use, in combining feasibility, accuracy, and reliability. To this end, the platform Biochem-Env optimized a miniaturized method to measure enzyme activities in soils using colorimetric substrates in micro-well plates. The standardization of the method was carried out within the framework of ISO/TC 190/SC 4/WG 4 "Soil quality - Biological methods" workgroup, recommending an inter-laboratory evaluation for the publication of a full ISO standard. That evaluation, managed by the platform, was based on the measurement, in six soils of contrasted physicochemical properties, of the ten soil enzyme activities described in the standard. Eight laboratories were involved in the validation study. Only 2.7% of outliers were identified from the analyses of the whole dataset. The repeatability and reproducibility of the method were determined by computing, respectively, the intra-laboratory (CVr,) and inter-laboratory (CVR) coefficients of variation for each soil and enzyme. The mean CVr ranged from 4.5% (unbuffered phosphatase) to 9.9% (alpha-glucosidase), illustrating a reduced variability of enzyme activities within laboratories. The mean CVR ranged from 13.8% (alkaline phosphatase) to 30.9% (unbuffered phosphatase). Despite this large CVR noticed for unbuffered phosphatase, the method was repeatable, reproducible, and sensitive. It also proved to be applicable for measuring enzyme activities in different types of soils. These results have been found successful by ISO/TC 190/SC4 and resulted in the publication of ISO 20130:2018 standard.

The evaluation of soil quality requires the use of robust methods to assess biologically based indicators. Among them, enzyme activities are used for several decades, but there is a clear need to update their measurement methods for routine use, in combining feasibility, accuracy, and reliability. To this end, the platform Biochem-Env optimized a miniaturized method to measure enzyme activities in soils using colorimetric substrates in micro-well plates. The standardization of the method was carried out within the framework of ISO/TC 190/SC 4/WG 4 “Soil quality – Biological methods” workgroup, recommending an inter-laboratory evaluation for the publication of a full ISO standard. That evaluation, managed by the platform, was based on the measurement, in six soils of contrasted physicochemical properties, of the ten soil enzyme activities described in the standard. Eight laboratories were involved in the validation study. Only 2.7% of outliers were identified from the analyses of the whole dataset. The repeatability and reproducibility of the method were determined by computing, respectively, the intra-laboratory (CVᵣ,) and inter-laboratory (CVR) coefficients of variation for each soil and enzyme. The mean CVᵣ ranged from 4.5% (unbuffered phosphatase) to 9.9% (α-glucosidase), illustrating a reduced variability of enzyme activities within laboratories. The mean CVR ranged from 13.8% (alkaline phosphatase) to 30.9% (unbuffered phosphatase). Despite this large CVR noticed for unbuffered phosphatase, the method was repeatable, reproducible, and sensitive. It also proved to be applicable for measuring enzyme activities in different types of soils. These results have been found successful by ISO/TC 190/SC4 and resulted in the publication of ISO 20130:2018 standard.

International audience | The effect of wastewater irrigation on the diversity and composition of bacterial communities of soil mesocosms planted with lettuces was studied over an experiment made of five cultivation campaigns. A limited effect of irrigation with either raw or treated wastewater was observed in both alpha-diversity and beta-diversity of soil bacterial communities. However, the irrigation with wastewater fortified with a complex mixture of fourteen relevant chemicals at 10 mu g/L each, including pharmaceutical, biocide, and pesticide active substances, led to a drift in the composition of soil bacterial community. One hundred operational taxonomic units (OTUs) were identified as responsible for changes between treated and fortified wastewater irrigation treatments. Our findings indicate that under a realistic agronomical scenario, the irrigation of vegetables with domestic (treated or raw) wastewater has no effect on soil bacterial communities. Nevertheless, under the worst-case scenario tested here (i.e., wastewater fortified with a mixture of chemicals), non-resilient changes were observed suggesting that continuous/repeated irrigation with wastewater could lead to the accumulation of contaminants in soil and induce changes in bacterial communities with unknown functional consequences.

The effect of wastewater irrigation on the diversity and composition of bacterial communities of soil mesocosms planted with lettuces was studied over an experiment made of five cultivation campaigns. A limited effect of irrigation with either raw or treated wastewater was observed in both α-diversity and β-diversity of soil bacterial communities. However, the irrigation with wastewater fortified with a complex mixture of fourteen relevant chemicals at 10 μg/L each, including pharmaceutical, biocide, and pesticide active substances, led to a drift in the composition of soil bacterial community. One hundred operational taxonomic units (OTUs) were identified as responsible for changes between treated and fortified wastewater irrigation treatments. Our findings indicate that under a realistic agronomical scenario, the irrigation of vegetables with domestic (treated or raw) wastewater has no effect on soil bacterial communities. Nevertheless, under the worst-case scenario tested here (i.e., wastewater fortified with a mixture of chemicals), non-resilient changes were observed suggesting that continuous/repeated irrigation with wastewater could lead to the accumulation of contaminants in soil and induce changes in bacterial communities with unknown functional consequences.