Impact of imidazolium ionic liquid on biochemistry of marine mussels Mytilus trossulus

Ionic liquids (ILs) are increasingly used in industrial applications, raising concerns about their environmental fate and toxicity in marine ecosystems. However, their impact on marine organisms, particularly under different salinity conditions, remains poorly understood. This study investigates the bioaccumulation and biochemical effects of 1-decyl-3-methylimidazolium chloride ([IM1-10] Cl) in Mytilus trossulus under salinities of 8 and 16 PSU. Mussels were exposed to [IM1-10] Cl for 21 days, followed by a 21-day depuration period. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) quantified IL accumulation, while biochemical assays assessed oxidative stress, detoxification responses, and lipid metabolism alterations. The [IM1-10] Cl was significantly accumulated in mussel tissues (511 ± 163 - 1347 ± 204 μg kg^-1 DW). The substantially higher accumulation was observed at 16 PSU, suggesting salinity-dependent bioavailability. During depuration, IL levels declined gradually, yet complete elimination was not achieved. Biomarker analysis showed increased oxidative stress and neurotoxicity. Carboxylesterases (CEs) were significantly modulated, suggesting detoxification responses. Fatty acid profiling revealed reductions in polyunsaturated fatty acids and altered enzyme activity (ELOVL1, ELOVL6 and SCD1), implying disruptions in membrane stability and energy metabolism. These biochemical effects persisted beyond the depuration period, indicating potential long-term physiological consequences.