Dube_2026_Ecotoxicol.Environ.Saf_321_120459

Human pharmaceuticals are increasingly recognised as "emerging pollutants" in the Arctic, yet their effects on native organisms remain poorly understood. One such pharmaceutical, carbamazepine, a sodium channel blocker, has recently been detected in Arctic marine ecosystems. In this study, we examine the effects of carbamazepine on the scallop Chlamys islandica following exposure to environmentally relevant concentrations of 0, 50, and 1000 L(-1) through a seven-day exposure experiment conducted in Ny-Alesund, Svalbard. We assessed gill tissue weight, biomarkers (acetylcholinesterase (AChE), catalase (CAT), carbonyl protein content (CBO), glutathione-s-transferase (GST), malondialdehyde (MDA), and superoxide dismutase (SOD), alongside histological biomarkers in gill tissue to evaluate physiological and oxidative stress responses following carbamazepine exposure. In addition, we investigated the effects of carbamazepine on tissue calcium dynamics, a process that has been hypothesised to be affected by pharmaceutical exposure but has not previously been demonstrated in this species. This was achieved through analyses of free cytosolic Ca(2+), histopathology supported by image processing techniques, and both enzymatic and non-enzymatic biomarker analyses Our findings reveal previously unreported effects of carbamazepine on the gill tissue of Chlamys islandica. We observed increased localised calcium deposition within gill tissue, accompanied by a reduction in overall tissue calcium concentration, suggesting altered calcium regulation and distribution. Moreover, exposure to carbamazepine impaired biomarker responses within Chlamys islandica gill tissue, with acetylcholinesterase activity and malondialdehyde levels showing the strongest concentration-dependent responses. These results indicate that carbamazepine influences gill physiology beyond oxidative stress pathways, affecting tissue mass, calcium regulation, and calcification processes in Chlamys islandica.