International audience | In the French West Indies (Caribbean), the insecticide Chlordecone (CLD) has been extensively used to reducebanana weevil (Cosmopolites sordidus) infestations in banana plantations. Previous studies have shown high CLDconcentrations in freshwater and coastal communities of the region. CLD concentrations, however, have not yetbeen assessed in marine top predators. We investigated CLD concentrations in cetacean blubber tissues fromGuadeloupe, including Physeter macrocephalus, Lagenodelphis hosei, Stenella attenuata and Pseudorca crassidens.Chlordecone was detected in all blubber samples analysed, with the exception of four P. macrocephalus.Concentrations (range: 1 to 329 ng·g−1 of lipid weight) were, however, lower than those found in species fromfresh and brackish water. Ecological factors (open ocean habitat), CLD kinetics, and cetacean metabolism (highor specific enzymatic activity) might explain low concentrations found in cetacean blubber. Future analyses thatinclude internal organ sampling would help to confirm CLD levels observed in this study.

International audience | Trace elements (TEs) availability, biochemical activity and functional gene diversity was studied in a Cu-contaminated soil, revegetated for six years with a mixed stand of willow, black poplar, and false indigo-bush, and amended or not with compost plus dolomitic limestone (OMDL). The OMDL amendment significantly reduced Cu and As availability and soil toxicity, and increased the biochemical activity and microbial functional diversity assessed with the GEOCHIP technique, as compared to the unamended soil (Unt). The OMDL soil showed significantly higher abundance of 25 functional genes involved in decomposition organic compounds, and 11, 3 and 11 functional genes involved in the N, P and S biogeochemical cycles. Functional gene abundance was positively correlated with nutrient contents but negatively correlated with Cu availability and soil toxicity. The abundance of microbial functional genes encoding for resistance to various TEs also increased, possibly due to the microbial proliferation and lower Cu exposure in the presence of high total soil Cu concentration. Genes encoding for antibiotic resistance due to the co-occurrence of TEs and antibiotic resistant genes on genetic mobile elements. Overall, phytomanagement confirmed its potential to restore the biological fertility and diversity of a severely Cu-contaminated soil, but the increase of TEs and antibiotic resistant gene abundances deserve attention in future studies.

International audience | Antibiotic resistance is a global public health issue and metal exposure can co-select for antibiotic resistance. We examined genome sequences of three multi-drug and metal resistant bacteria: one Shewanella sp., and two Vibrio spp., isolated from the gut of the mummichog fish (Fundulus heteroclitus). Our primary goal was to understand the mechanisms of co-selection. Phenotypically, the strains showed elevated resistance to arsenate, mercury, and various types of β-lactams. The genomes contained genes of public health concern including one carbapenemase (bla OXA-48). Our analyses indicate that the co-selection phenotype is mediated by chromo-somal resistance genes and cross-resistance. No evidence of co-resistance was found; most resistance genes were chromosomally located. Moreover, the identification of many efflux pump gene homologs indicates that cross-resistance and/or co-regulation may further contribute to resistance. We suggest that the mummichog gut microbiota may be a source of clinically relevant antibiotic resistance genes.

International audience | Climate change and human activities induce an increased frequency and intensity of cyanobacterial blooms which could release toxins to aquatic ecosystems. Zooplankton communities belong to the first affected organisms, but in tropical freshwater ecosystems, this issue has yet been poorly investigated. We tested two questions (i) if the tropical Daphnia lumholtzi is capable to develop tolerance to an ecologically relevant concentration of purified microcystin-LR and microcystins from cyanobacterial extract transferable to F1 and F2 generations? And (ii) would F1 and F2 generations recover if reared in toxin-free medium? To answer these questions, we conducted two full factorial mutigenerational experiments, in which D. lumholtzi was exposed to MC-LR and cyanobacterial extract at the concentration of 1 μg L microcystin continuously for three generations. After each generation, each treatment was spit into two one reared in the control (toxin free) while the other continued in the respective exposure. Fitness-related traits including survival, maturity age, body length, and fecundity of each D. lumholtzi generation were quantified. Though there were only some weak negative effects of the toxins on the first generation (F0), we found strong direct, accumulated and carried-over impacts of the toxins on life history traits of D. lumholtzi on the F1 and F2, including reductions of survival, and reproduction. The maturity age and body length showed some inconsistent patterns between generations and need further investigations. The survival, maturity age (for extract), and body length (for MC-LR) were only recovered when offspring from toxin exposed mothers were raised in clean medium for two generations. Chronic exposure to long lasting blooms, even at low density, evidently reduces survival of D. lumholtzi in tropical lakes and reservoirs with ecological consequences.

Constructed Wetlands receiving treated wastewater (CWtw) have recently become attractive in France under the perception that they would increase water quality of the WWTP effluent. This study focuses on the fate of phosphorus (P) in 2 pilot-scale CWtw after 2 years of operation considering the 3 components: water, soil and plants. P mass balance was estimated by measures of water balance (inflow outflow and infiltration), flow composite samples, grab samples, water in soil, deposits, soil and plants samples. When considering inlet/outlet an efficiency of 83% and 39 % P removal was observed respectively in M1 and M2. Since the plant uptake was of 15-25 % of total P removal in both systems, the remaining fraction was either retained in the soil or infiltrated. Removal of P by harvesting of aboveground biomass is relevant in that case because of a lightly load system and confirms the need for a harvesting per year to avoid the release of up to 7 kg of P.

The main treatment technologies implemented in the French Overseas Territories are compared based on the analysis of self-monitoring database built for this study. Activated sludge is the most implemented but least reliable technology, due to sludge leakages noticeable on 10% of the campaigns. Algae growth limits facultative ponds performances. Settling troubles have been identified on rotative biological contactor. Vertical flow treatment wetlands show the best performances. Coefficient Of Reliability use and comparison with data from Brazil confirm those results.