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Nowadays, biomarkers are recognized as valuable tools to complement chemical and ecological assessments in biomonitoring programs. They provide insights into the effects of contaminant exposures on individuals and establish connections between environmental pressure and biological response at higher levels. In the last decade, strong improvements in the design of experimental protocols and the result interpretation facilitated the use of biomarker across wide geographical areas, including aquatic continua. Notably, the statistical establishment of reference values and thresholds enabled the discrimination of contamination effects in environmental conditions, allowed interspecies comparisons, and eliminated the need of a reference site. The aim of this work was to study freshwater-estuarine-coastal water continua by applying biomarker measurements in multi-species caged organisms. During two campaigns, eight sentinel species, encompassing fish, mollusks, and crustaceans, were deployed to cover 25 sites from rivers to the sea. As much as possible, a common methodology was employed for biomarker measurements (DNA damage and phagocytosis efficiency) and data interpretation based on guidelines established using reference values and induction/inhibition thresholds (establishment of three effect levels). The methodology was successfully implemented and allowed us to assess the environmental quality. Employing multiple species per site enhances confidence in observed trends. The results highlight the feasibility of integrating biomarker-based environmental monitoring programs across a continuum scale. Biomarker results align with Water Framework Directive indicators in cases of poor site quality. Additionally, when discrepancies arise between chemical and ecological statuses, biomarker findings offer a comprehensive perspective to elucidate the disparities. Presented as a pilot project, this work contributes to gain insights into current biomonitoring needs, providing new questions and perspectives., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

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., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

On September 26th 2019, a major fire occurred in the Lubrizol factory located near the Seine estuary, in Rouen-France. Juvenile flounders were captured in the Canche estuary (a reference system) and caged one month in the Canche and in the Seine downstream the accident site. No significant increases of PAHs, PCBs and PFAS was detected in Seine vs Canche sediments after the accident, but a significant increase of dioxins and furans was observed in water and sewage sludge in the Rouen wastewater treatment plant. The proteomics approach highlighted a dysregulation of proteins associated with cholesterol synthesis and lipid metabolism, in fish caged in the Seine. The overall results suggested that the fire produced air borne dioxins and furans that got deposited on soil and subsequently entered in the Seine estuarine waters via runoff; thus contaminating fish preys and caged flounders in the Seine estuary. [Display omitted] • 10,000 tons of heavy hydrocarbons burnt in two factories near the Seine estuary. • Juvenile flounders were caged during one month downstream the accident site. • Brain AChE activity was reduced in caged fish after the accident. • Caged fish showed an upregulation of the liver cholesterol and fatty acid synthesis. • Dioxins and furans probably contaminated the Seine estuary through runoff. [ABSTRACT FROM AUTHOR]

The use of a multi-biomarker approach with three-spined sticklebacks (Gasterosteus aculeatus) through an active biomonitoring strategy appears to be a promising tool in water quality assessment. The present work proposes to assess the efficiency of these tools in the discrimination of some sites in a large scale on the Meuse basin in Europe. The study was part of an EU program which aims to assess water quality in the Meuse across the French-Belgian border. Sticklebacks were caged 21 days upstream and downstream from the wastewater treatment plants (WWTPs) of Namur (Belgium), Charleville-Mézières (France), Bouillon (Belgium) and Avesnes-sur-Helpe (France). First, the state of a variety of physiological functions was assessed using a battery of biomarkers that represented innate immunity (leucocyte mortality and distribution, phagocytosis activity, respiratory burst), antioxidant system (GPx, CAT, SOD and total GSH content), oxidative damages to the membrane lipids (TBARS), biotransformation enzymes (EROD, GST), synaptic transmission (AChE) and reproduction system (spiggin and vitellogenin concentration). The impacts of the effluents were first analysed for each biomarker using a mixed model ANOVA followed by post-hoc analyses. Secondly, the global river contamination was assessed using a principal component analysis (PCA) followed by a hierarchical agglomerative clustering (HAC). The results highlighted a small number of effects of WWTP effluents on the physiological parameters in caged sticklebacks. Despite a significant effect of the "localisation" factor (upstream/downstream) in the mixed ANOVA for several biomarkers, post-hoc analyses revealed few differences between upstream and downstream of the WWTPs. Only a significant decrease of innate immune responses was observed downstream from the WWTPs of Avesnes-sur-Helpe and Namur. Other biomarker responses were not impacted by WWTP effluents. However, the multivariate analyses (PCA and HAC) of the biomarker responses helped to clearly discriminate the different study sites from the reference but also amongst themselves. Thus, a reduction of general condition (condition index and HSI) was observed in all groups of caged sticklebacks, associated with a weaker AChE activity in comparison with the reference population. A strong oxidative stress was highlighted in fish caged in the Meuse river at Charleville-Mézières whereas sticklebacks caged in the Meuse river at Namur exhibited weaker innate immune responses than others. Conversely, sticklebacks caged in the Helpe-Majeure river at Avesnes-sur-Helpe exhibited higher immune responses. Furthermore, weak defence capacities were recorded in fish caged in the Semois river at Bouillon. This experiment was the first to propose an active biomonitoring approach using three-spined stickleback to assess such varied environments. Low mortality and encouraging results in site discrimination support the use of this tool to assess the quality of a large number of water bodies., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Brest harbor (Bay of Brest, Brittany, France) has a severe past of anthropogenic chemical contamination, but inputs tended to decrease, indicating a reassessment of its ecotoxicological status should be carried out. Here, native and caged mussels (Mytilus spp.) were used in combination to evaluate biological effects of chronic chemical contamination in Brest harbor. Polycyclic aromatic hydrocarbon (PAH) contamination was measured in mussel tissues as a proxy of harbor and urban pollution. Biochemical biomarkers of xenobiotic biotransformation, antioxidant defenses, generation of reducing equivalents, energy metabolism and oxidative damage were studied in both gills and digestive glands of native and caged mussels. In particular, activities of glutathione-S-transferase (GST), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), NADP-dependent isocitrate dehydrogenase (IDP), pyruvate kinase (PK) and phosphoenolpyruvate carboxykinase (PEPCK) were measured and lipid peroxidation was assessed by malondialdehyde (MDA) quantification. In addition, a condition index was calculated to assess the overall health of the mussels. Moderate PAH contamination was detected in digestive glands of both native and caged individuals from the exposed site. Modulations of biomarkers were detected in digestive glands of native harbor mussels indicating the presence of a chemical pressure. In particular, results suggested increased biotransformation (GST), antioxidant defenses (CAT), NADPH generation (IDP) and gluconeogenesis (PEPCK), which could represent a coordinated response against chemically-induced cellular stress. Lipid peroxidation assessment and condition index indicated an absence of acute stress in the same mussels suggesting metabolic changes could, at least partially, offset the negative effects of contamination. In caged mussels, only GR was found modulated compared to non-exposed mussels but significant differences in oxidative stress and energy-related biomarkers were observed compared to native harbor mussels. Overall, these results suggested mussels chronically exposed to contamination have set up metabolic adaptation, which may contribute to their survival in the moderately contaminated harbor of Brest. Whether these adaptive traits result from phenotypic plasticity or genetic adaptation needs to be further investigated., (Copyright © 2015 Elsevier B.V. All rights reserved.)