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Biomonitoring appears to be a key approach to assess chemical or microbiological contaminations. The freshwater mussel, Dreissena polymorpha (D. polymorpha), is a suitable tool already used to monitor chemical and, more recently, microbiological pollution. In the present study, we used this sentinel species to monitor viral contamination of fecal origin over a wide geographical distribution. An active approach was implemented based on caging of calibrated and pathogen-free organisms with the same exposure conditions, allowing spatio-temporal comparisons between different water bodies. In addition, different types of sites were selected to investigate the range of environmental concentrations that D. polymorpha are able to translate. Different viral genome targets were measured: norovirus genogroup I and II (NoV GI and GII) and F-specific RNA bacteriophages belonging to the genogroup -I and -II (FRNAPH-I and -II). Total infectious FRNAPH were also monitored. D. polymorpha was able to translate a wide range of concentrations for all the viral targets studied, meaning that this sentinel species can be used for both low and highly anthropised sites. Moreover, D. polymorpha caging proved effective in achieving gradients of viral contamination of fecal origin pressure and to highlight the contribution of tributaries to the main rivers. D. polymorpha provided spatial and temporal variations of the viral contamination. It allowed to highlight the prevalence of the FRNAPH-I and -II genogroups according to the caging site. FRNAPH-II was found to be dominant in urban areas and FRNAPH-I in rural areas. This strategy uses the caging of the sentinel species D. polymorpha on selected sites with standardised analysis methods has proven to be a promising tool for characterizing viral contamination at both large and very fine scales., 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. Published by Elsevier Ltd.)

Rare earth elements (REEs) are metallic elements with electronic, magnetic, optical and catalytic properties which make them essential in many industrial and medical fields. REEs are therefore becoming emerging pollutants and it is important to understand their implications for ecosystem health. However, little knowledge of REE bioaccumulation in aquatic organisms is available and especially on their internal distribution in fish. In the present study, REE organotropism was determined in Anguilla anguilla from the Loire estuary (France) by determining burdens in a wide set of tissues, organs and biological fluids. Differences have been observed between life stages and genders. For yellow eels, the most accumulating organ was the gills (126.90 ± 50.78 μg/kg dw) and for silver eels, it was the liver (181.78 ± 62.04 μg/kg dw for males; 203.79 ± 111.86 μg/kg dw for females). The comparison between female silver and yellow eels shown that female silver individuals accumulated significantly more REEs in the urinary system (US), muscles, gonads, spleen and liver, while yellow individuals accumulated more in gills. The comparison between male and female silver eels also highlighted differences, indeed the females accumulated significantly more REEs in the US, gonads, skin and spleen, compared to males which accumulated significantly more in muscles and gills. REEs abundances are also different between organs, life stages and genders. The gonads of female silver eels exhibited a particular profile with the dominance of gadolinium (Gd) (up to 74.2% of ∑REEs). Moreover, the presence of Anguillicola crassus in the swim bladder of organisms seemed to have an impact on REE bioaccumulation: parasitized yellow eels present higher concentrations of REEs in muscles, gills, gonads and liver than non-parasitized individuals. Regarding glass eels, REE contribution profiles in the whole body were close to those of yellow and silver eel skin., 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 © 2020 Elsevier B.V. All rights reserved.)

In the present work, rare earth elements (REEs) were measured in European eel muscles (Anguilla anguilla) from the Loire estuary in France. This study site is characterized by a large anthropogenic pressure with potential activities releasing REEs such as oil refineries, aeronautic and naval industries, wind turbine industries, hospitals with magnetic resonance imaging and coal-fired power plants. These activities may lead to increased REE concentrations in sediments the primary habitat of European eels. In the present work, REE bioaccumulation was evaluated by determining the concentrations in yellow and silver eel muscles sampled at three different locations in the Loire estuary and at two periods (2011/2012 and 2018/2019). The aims of this study were the understanding of the spatio-temporal influences (sampling site and sampling period) and intraspecific variations (age, sex, sexual maturation, length, weight, and parasitism) on the whole REE bioaccumulation. The mean value of the sum of REE concentrations (∑REEs) was 2.91, 6.48 and 12.60 µg/kg of muscle from respectively yellow eels, female silver eels and male silver eels fished in 2018/2019. The results showed that silver males accumulated more REEs than silver females and silver eels accumulate more REEs than yellow ones. Regarding the determination of spatio-temporal variations, an increase of REE concentrations for silver eel muscles between the two periods was observed, certainly related to the increase of REE uses. Finally, a trend of higher contamination of eels sampled in the downstream of Nantes was noticed for yellow eels., Competing Interests: Declaration of Competing Interest The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as potential conflict of interest., (Copyright © 2019 Elsevier B.V. All rights reserved.)