Accumulation of Emerging Contaminants in Aquatic Fauna from River Louro (International Stretch of the Minho River): Interspecific and Functional Comparison ^†

Emerging contaminants constitute a growing pressure on river ecosystems due to their persistence, chemical diversity, and ecotoxicological effects. The objective of this study was to analyze the presence of these compounds in muscle tissue across a range of aquatic species, including benthic fish (Gobio lozanoi, Cobitis sp.), nektonic species (Salmo trutta, Lepomis gibbosus), diadromous species (Anguilla anguilla, Petromyzon marinus, in the larval stage), generalist species (Pseudochondrostoma duriense), and crustaceans (Procambarus clarkii). Concentrations were determined using LC-MS/MS, grouping the compounds into different chemical families (e.g., pharmaceuticals, personal care products, industrial compounds, and other emerging contaminants). The results showed significant differences both among species and among compound families. At the interspecific level, Petromyzon marinus (larvae) exhibited the highest total concentrations, followed by Salmo trutta and benthic species such as Gobio lozanoi and Cobitis sp. Intermediate values were observed in Pseudochondrostoma duriense and Lepomis gibbosus, while Anguilla anguilla showed moderate levels. Procambarus clarkii displayed notable accumulation, especially of sediment-associated compounds. Analysis by compound families revealed distinct patterns: pharmaceutical and personal care compounds showed a relatively homogeneous distribution among species, whereas more hydrophobic and industrial compounds tended to accumulate in species with higher lipid content or greater benthic exposure. In particular, benthic species (lamprey larvae, gudgeon, spined loach, and crayfish) showed higher accumulation of sediment-associated compounds, confirming their role as contaminant reservoirs. Lamprey larvae, which exhibit filter-feeding behavior and remain buried in fine sediments for several years, showed high accumulation of multiple contaminant families, highlighting the importance of this life stage as an indicator of environmental contamination. The results demonstrate the coexistence of different accumulation mechanisms: (i) direct exposure to sediment, (ii) trophic biomagnification, and (iii) accumulation linked to the physicochemical properties of the compounds. This combined approach by species and contaminant families allows for a more comprehensive assessment of the ecological status of the system. Finally, the relevance of including multiple taxonomic groups and life cycle stages in monitoring programs is emphasized, especially in vulnerable species such as Petromyzon marinus.