Metabolic saboteurs: Tire wear particles hijack energy economy of zooplankton

Tire wear particles (TWP) represent a significant source of marine microplastic pollution and have been shown to pose a considerable threat to marine organisms. In this study, the marine rotifer Brachionus plicatilis was employed as a model organism to systematically assess the effects of micron-sized and nano-sized TWP, as well as their leachates, on rotifer behavior, and underlying molecular mechanisms. The results revealed that TWP exposure significantly reduced rotifer motility, evidenced by decreased swimming speed and acceleration. Further investigation revealed that TWP-induced suppression of rotifer motility was mechanistically linked to metabolic disturbances (reduced amylase activity, triglyceride, and neutral lipid levels) and mitochondrial dysfunction (oxidative stress, ATP depletion, and autophagy activation). Concurrently, rotifers counteracted TWP-induced stress by activating oxidative stress responses and mitophagy pathways, while concurrently initiating compensatory feeding to alleviate energy depletion. Notably, N-acetylcysteine supplementation significantly mitigated TWP-induced mitochondrial dysfunction and metabolic disturbances. Furthermore, a significant dose-dependent decline in Biomarker Response Index (BRI) values was observed with increasing TWP concentrations. This study elucidates TWP's toxic mechanisms in aquatic organisms and underscores low-concentration exposure risks, providing key evidence for assessing long-term ecological impacts of microplastic pollution.