Emerging pollutants, such as pharmaceuticals and microplastics have become a pressing concern due to their widespread presence and potential impacts on ecological systems. To assess the ecosystem-level effects of these pollutants within a multi-stressor context, we simulated real-world conditions by exposing a near-natural multi-trophic aquatic food web to a gradient of environmentally relevant concentrations of fluoxetine and microplastics in large mesocosms over a period of more than three months. We measured the biomass and abundance of different trophic groups, as well as ecological functions such as nutrient availability and decomposition rate. To explore the mechanisms underlying potential community and ecosystem-level effects, we also performed behavioral assays focusing on locomotion parameters as a response variable in three species: Daphnia magna (zooplankton prey), Chaoborus flavicans larvae (invertebrate pelagic predator of zooplankton) and Asellus aquaticus (benthic macroinvertebrate), using water from the mesocosms. Our mesocosm results demonstrate that presence of microplastics governs the response in phytoplankton biomass, with a weak non-monotonic dose-response relationship due to the interaction between microplastics and fluoxetine. However, exposure to fluoxetine evoked a strong non-monotonic dose-response in zooplankton abundance and microbial decomposition rate of plant material. In the behavioral assays, the locomotion of zooplankton prey D. magna showed a similar non-monotonic response primarily induced by fluoxetine. Its predator C. flavicans, however, showed a significant non-monotonic response governed by both microplastics and fluoxetine. The behavior of the decomposer A. aquaticus significantly decreased at higher fluoxetine concentrations, potentially leading to reduced decomposition rates near the sediment. Our study demonstrates that effects observed upon short-term exposure result in more pronounced ecosystem-level effects following chronic exposure.

The influence of algae presence in surface water on the settling velocities of microplastics is unknown, and determining it is challenging due to the turbidity of algal suspensions. Measuring the settling velocity of microplastics has traditionally relied on either manual measurement techniques or 2D Particle Tracking Velocimetry (PTV). This study introduces a 3D-PTV method tailored to determine the effects of algae (Synechoccocus sp.) on microplastic settling speeds in semi-large columns. We demonstrated that 3D PTV produces much more accurate results than 2D particle tracking. Testing the method in six experiments with varying algae concentrations revealed consistent results across the experiments and alignment with some theoretical approximations. The results were concurrent with calculated 2D speeds. No influence of algal density on settling velocities was found, which is highly relevant for microplastic fate modeling in eutrophic systems. We highlight the applicability and accuracy of 3D particle tracking velocimetry in further understanding microplastic settling behavior.

Microplastics (MPs) are carriers of persistent organic pollutants (POPs). The influence of MPs on the toxicokinetics of POPs was investigated in a feeding experiment on Atlantic salmon (Salmo salar), in which fish were fed similar contaminant concentrations in feed with contaminants sorbed to MPs (Cont. MPs); feed with virgin MPs and contaminated feed (1:1), and feed with contaminants without MPs (Cont.). The results showed that the salmon fillets accumulated more POPs when fed with a diet where contaminants were sorbed to the MPs, despite the 125–250 μm size MPs themselves passing the intestines without absorption. Furthermore, depuration was significantly slower for several contaminants in fish fed the diet with POPs sorbed to the MPs. Modelled elimination coefficients and assimilation efficiencies of lipophilic chlorinated and brominated contaminants correlated with contaminant hydrophobicity (log Kow) within the diets and halogen classes. The more lipophilic the contaminant was, the higher was the transfer from feed to salmon fillet. The assimilation efficiency for the diet without MPs was 50–71% compared to 54–89% for the contaminated MPs diet. In addition, MPs caused a greater proportional uptake of higher molecular weight brominated congeners. In the present study, higher assimilation efficiencies and a significantly higher slope of assimilation efficiencies vs log Kow were found for the Cont. MPs diet (p = 0.029), indicating a proportionally higher uptake of higher-brominated congeners compared to the Cont. diet. Multiple variance analyses of elimination coefficients and assimilation efficiencies showed highly significant differences between the three diets for the chlorinated (p = 2E-06; 6E-04) and brominated (p = 5E-04; 4E-03) congeners and within their congeners. The perfluorinated POPs showed low assimilation efficiencies of 12%, which can be explained by faster eliminations corresponding to half-lives of 11–39 days, as well as a lower proportional distribution to the fillet, compared to e.g. the liver.

Antimicrobial resistance (AMR) is a burgeoning environmental concern demanding a comprehensive One Health investigation to thwart its transmission to animals and humans, ensuring food safety. Seafood, housing bacterial AMR, poses a direct threat to consumer health, amplifying the risk of hospitalization, invasive infections, and death due to compromised antimicrobial treatments. The associated antimicrobial resistance genes (ARGs) in diverse marine species can amass and transmit through various pathways, including surface contact, respiration, and feeding within food webs. Our research, focused on the English Channel and North Sea, pivotal economic areas, specifically explores the occurrence of four proposed AMR indicator genes (tet(A), blaTEM, sul1, and intI1) in a benthic food web. Analyzing 350 flatfish samples' skin, gills, and gut, our quantitative PCR (qPCR) results disclosed an overall prevalence of 71.4% for AMR indicator genes. Notably, sul1 and intI1 genes exhibited higher detection in fish skin, reaching a prevalence of 47.5%, compared to gills and gut samples. Proximity to major European ports (Le Havre, Dunkirk, Rotterdam) correlated with increased AMR gene frequencies in fish, suggesting these ports' potential role in AMR spread in marine environments. We observed a broad dispersion of indicator genes in the English Channel and the North Sea, influenced by sea currents, maritime traffic, and flatfish movements. In conclusion, sul1 and intI1 genes emerge as robust indicators of AMR contamination in the marine environment, evident in seawater and species representing a benthic food web. Further studies are imperative to delineate marine species' role in accumulating and transmitting AMR to humans via seafood consumption. This research sheds light on the urgent need for a concerted effort in comprehending and mitigating AMR risks in marine ecosystems within the context of One Health.

Staphylococcus is a significant food safety hazard. The marine environment serves as a source of food for humans and is subject to various human-induced discharges, which may contain Staphylococcus strains associated with antimicrobial resistance (AMR). The aim of this study was to assess the occurrence and geographical distribution of AMR Staphylococcus isolates in seawater and whiting (Merlangius merlangus) samples collected from the English Channel and the North Sea. We isolated and identified 238 Staphylococcus strains, including 12 coagulase-positive (CoPs) and 226 coagulase-negative (CoNs) strains. All CoPs isolates exhibited resistance to at least one of the 16 antibiotics tested. Among the CoNs strains, 52% demonstrated resistance to at least one antibiotic, and 7 isolates were classified as multi-drug resistant (MDR). In these MDR strains, we identified AMR genes that confirmed the resistance phenotype, as well as other AMR genes, such as quaternary ammonium resistance. One CoNS strain carried 9 AMR genes, including both antibiotic and biocide resistance genes. By mapping the AMR phenotypes, we demonstrated that rivers had a local influence, particularly near the English coast, on the occurrence of AMR Staphylococcus. The analysis of marine environmental parameters revealed that turbidity and phosphate concentration were implicated in the occurrence of AMR Staphylococcus. Our findings underscore the crucial role of wild whiting and seawater in the dissemination of AMR Staphylococcus within the marine environment, thereby posing a risk to human health.

Tracking PFAS in ecosystems is challenging. In this context, monitoring programs are crucial to fill data gaps, especially in marine environments, which are the ultimate outlets for these forever chemicals. The 2021 chemical contamination monitoring campaign along the French Mediterranean coast established a baseline for PFAS concentrations in mussels, with 90 % of measurements below quantification limits. When detected, long-chain PFCA's were predominant. Spatial distribution patterns suggested continuous PFAS inputs and complex dynamics, shaped by the influence of large watersheds and rivers (Rhône, Aude, Huveaune). Lapeyrade shallow lagoon stood out as the most contaminated site. Similar PFAS profiles in connected sites implied shared sources but raised questions about accumulation processes in mussels. While certain sites had evident sources (e.g., military airbase for Palo lagoon), others remained uncertain (e.g., Toulon bay). Coastal stations (Banyuls, Cap Agde, Brégançon, Pampelonne) showed PFAS contamination without clear onshore sources, possibly due to insufficient transportation process understanding.

The progressive increase of marine macro-litter on the bottom of the Mediterranean Sea is an urgent problem that needs accurate information and guidance to identify those areas most at risk of accumulation. In the absence of dedicated monitoring programs, an important source of opportunistic data is fishery-independent monitoring campaigns of demersal resources. These data have long been used but not yet extensively. In this paper, MEDiterranean International Trawl Survey (MEDITS) data was supplemented with 18 layers of information related to major environmental (e.g. depth, sea water and wind velocity, sea waves) and anthropogenic (e.g. river inputs, shipping lanes, urban areas and ports, fishing effort) forcings that influence seafloor macro-litter distribution. The Random Forest (RF), a machine learning approach, was applied to: i) model the distribution of several litter categories at a high spatial resolution (i.e. 1 km2); ii) identify major accumulation hot spots and their temporal trends. Results indicate that RF is a very effective approach to model the distribution of marine macro-litter and provides a consistent picture of the heterogeneous distribution of different macro-litter categories. The most critical situation in the study area was observed in the north-eastern part of the western basin. In addition, the combined analysis of weight and density data identified a tendency for lighter items to accumulate in areas (such as the northern part of the Tyrrhenian Sea) with more stagnant currents. This approach, based on georeferenced information widely available in public databases, seems a natural candidate to be applied in other basins as a support and complement tool to field monitoring activities and strategies for protection and remediation of the most impacted areas.

The increase in trace element concentrations in the aquatic environment due to anthropogenic activities, urges the need for their monitoring and potential toxicity, persistence, bioaccumulation, and biomagnification at different trophic levels. Gilthead seabream is a species of commercial importance in the Mediterranean Sea, both for the aquaculture and fisheries sectors, however very little is known about their trace element contamination accumulation and the resulting effect on their health status. In the present study, 135 juveniles were collected from seven coastal lagoons known to be essential nursery areas for this species. We measured seventeen different inorganic contaminants at the individual level in fish muscle (namely Al, As, Be, Bi, Cd, Cr, Cu, Hg, Li, Ni, Pb, Rb, Sb, Sr, Ti, Tl and Zn). Our results revealed the accumulation of multiple trace elements in individuals and distinct contamination signatures between lagoons which might lead to contrasted quality as nurseries for juveniles of numerous ecologically and economically relevant fish species in addition to seabreams. We further evaluated the potential adverse effect of these complex contamination mixtures on the liver (the main organ implicated in the metabolism of xenobiotics) and red muscle (a highly metabolic organ) using a proteomic approach. Alterations in cellular organization pathways and protein transport were detected in both tissues (albeit they were not similarly regulated). Chromosome organization and telomere maintenance in the liver appeared to be affected by contaminant mixture which could increase mortality, age-related disease risk and shorter lifetime expectancy for these juveniles. Red muscle proteome also demonstrated an upregulation of pathways involved in metabolism in response to contamination which raises the issue of potential energy allocation trade-offs between the organisms’ main functions such as reproduction and growth. This study provides new insights into the cellular and molecular responses of seabreams to environmental pollution and proposed biomarkers of health effects of trace elements that could serve as a starting point for larger-scale biomonitoring programs.

International audience | To evaluate the effects of salinity on the fate of pesticides in a Mediterranean irrigated system, experiments were carried out under laboratory conditions to determine the adsorption, desorption, and mineralization of chlorpyrifos (CPF) and metalaxyl-M (MET) in a soil sample from an irrigated field in northern Tunisia. Adsorption/desorption isotherms and mineralization kinetics data were obtained over a realistic range of salinities via batch equilibrium and incubation techniques. On the basis of the experimental results, MET has a lower sorption capacity than CPF does, and the adsorption data for both compounds were better fitted by the Freundlich equation, with Kf values of 0.477, 0.486, 0.426, 0.444 and 0.474 L kg -1 for MET and 38.994, 39.084, 40.644, 44.055 and 45.185 L kg -1 for CPF at salinities of 0, 1, 2, 5 and 10 g L -1 , respectively. According to the mineralization experiments, increasing salinity increased the half-lives of both pesticides. For MET, the DT50 values in unsterilized soil were 206.68, 220.74, 222.16, and 238.73 days, and those in sterilized soil were 2772.58, 4077.33, 6301.33, and 8664.33 days at salinities of 0, 1, 2, 5, and 10 g L⁻¹, respectively. For CPF, the DT50 values were 115.52, 138.62, 157.53, and 177.73 days in unsterilized soil and 346.57, 533.19, 693.14, and 990.21 days in sterilized soil. In terms of leaching behavior, the calculated groundwater ubiquity score (GUS) values for the MET and CPF indicate that the MET is classified as a leacher and that the CPF is classified as a nonleacher.

A Correction to this article was published on 30 January 2024 https://doi.org/10.1007/s11356-024-32246-9 | International audience | The widespread use of copper-based pesticides, while effective in controlling plant diseases, has been identified as a major source of copper contamination in soils. This raises concerns about potential adverse effects on earthworms, key players in soil health and ecosystem function. To inform sustainable pesticide practices, this study aimed to establish copper toxicity thresholds for earthworm avoidance in agricultural soils impacted by copper-based pesticides. We collected 40 topsoil samples (0-5 cm) from orchards and vineyards in the O'Higgins Region of central Chile, and 10 additional soils under native vegetation as background references. A standardized avoidance bioassay using Eisenia fetida assessed the impact of copper-based pesticides on the soils. Total copper concentrations ranged between 23 and 566 mg kg -1 , with observed toxic effects on earthworms in certain soils. The effective concentration at 50% (EC 50 ) for total soil copper, determined by Eisenia fetida's avoidance response, was 240 mg kg -1 , with a 95% confidence interval of 193-341 mg kg -1 . We further compared our EC 50 values with existing data from agricultural soils impacted by mining activities. Interestingly, the results revealed a remarkable similarity between the thresholds for earthworm avoidance, regardless of the source of copper contamination. This observation underscores the universality of copper toxicity in agricultural ecosystems and its potential impact on soil biota. This study provides novel insights into copper toxicity thresholds for earthworms in real-world, pesticide-contaminated soils.