Species resistance and resilience to lithium and nickel stress: A comparative ecotoxicological assessment between mussels and clams

The rapid expansion of lithium-ion battery production has heightened the environmental relevance of lithium (Li) and nickel (Ni), sparking concerns about their potential release into aquatic ecosystems. This study investigated the ecotoxicological effects of Li and Ni, individually and in combination, as well as post-exposure recovery processes, in two ecologically and commercially important bivalves, the mussel Mytilus galloprovincialis and the clam Ruditapes philippinarum. Specimens were subjected to a 14-day exposure phase followed by a 14-day recovery period under clean water conditions. A comprehensive biomarker approach was applied to assess energy metabolism, antioxidant and detoxification responses, cellular damage, and neurotoxicity. Distinct species-specific response patterns were observed. Despite higher metal accumulation, mussels displayed relatively stable biochemical profiles during both exposure and recovery, indicating a higher capacity to withstand metal-induced stress. In contrast, clams showed pronounced activation of antioxidant and detoxification pathways, which was insufficient to fully restore biochemical parameters to control levels within the recovery period, resulting in persistent oxidative stress and energetic imbalance. Nickel induced stronger biological effects than Li, and combined exposure to both metals produced the most pronounced impacts, particularly in clams. Overall, the contrasting responses of mussels and clams reflect differences in exposure pathways and physiological strategies, highlighting their complementary value as bioindicators. These findings emphasise the importance of incorporating recovery dynamics into ecotoxicological assessments to better evaluate ecosystem vulnerability to emerging metal contaminants.