New insight into barium toxicity in the gills of the European clam (Ruditapes decussatus): a focus on redox status, fatty acids profiles, and histological structures

Barium (Ba) is a naturally occurring alkaline earth metal that is mined and used for industrial purposes. This earth metal can easily impact organisms commonly found in coastal zones, particularly marine bivalves, through aquatic discharges resulting from industrial activities. The aim of the present study was to assess the potential toxic effects of barium chloride (BaCl₂) on fatty acid profiling, redox status, and histopathological aspects of Ruditapes decussatus gills exposed to a range of concentrations (0, 20, 40, and 80 mg/L) for 5 days. Our results revealed that BaCl₂-treated clams had altered levels of saturated fatty acids, decreased content of monounsaturated fatty acids, and increased levels of polyunsaturated fatty acids. Alterations in arachidonic acid were also observed in the gills of treated specimens, accompanied by significant increases in its precursors: linoleic and α-linolenic acids. Our findings also showed changes in the levels of eicosapentaenoic and docosahexaenoic acids. These results indicated a bioaccumulation of Ba, as evidenced by a significant increase in Ba levels in BaCl₂-treated specimens. BaCl₂ exposure increased the levels of hydrogen peroxide, lipid hydroperoxide, malondialdehyde and protein carbonyl along with enzymatic (glutathione peroxidase and glutathione s-transferase) and non-enzymatic (reduced glutathione, non-protein thiols, metallothioneins, and vitamin c) antioxidants. Moreover, our data showed a decrease in ferric-reducing antioxidant power, superoxide dismutase, and catalase. The outcomes of the biochemical findings were confirmed by histopathological injuries. Our investigation underscores the significance of fatty acid composition as an early sensitive biomarker for elucidating the toxicity mechanisms of BaCl₂ in aquatic bivalves, and highlights the broader implications of BaCl₂ contamination in coastal ecosystems, emphasizing the need for monitoring and mitigation strategies. By demonstrating the link between oxidative stress and fatty acid profile disruptions, our findings provide valuable insights into the environmental impact of BaCl₂ and underscore the importance of continued research into its effects on marine life.