Hydrodynamic modulation of microplastic bioaccumulation in edible fish: Integrating biomarker networks, machine learning, and food safety perspectives

Microplastic (MP) pollution poses increasing environmental and food safety risks, yet the role of hydrodynamics in MPs bioaccumulation and fish physiology is unclear. This study assessed the effects of 5 μm polystyrene MPs (1000 μg/L) on Ctenopharyngodon idella under static conditions and at water velocities of 1, 3, and 5 body lengths per second (BL/s). Fish exposed to high velocity showed highest MPs bioaccumulation (58.1 ± 10.5 × 10³ μg/kg), and histological damage, including fiber degeneration, necrosis, and hemorrhage. Biomarkers indicated oxidative stress, neurotoxicity, and disrupted energy metabolism, while endocrine and neurochemical disturbances reflected systemic stress and reduced tissue quality. Factorial ANOVA and structural equation modeling revealed independent and synergistic effects of MPs and hydrodynamics on muscle damage. Machine learning identified ATPase, superoxide dismutase, and cholinesterase as key predictive biomarkers (87.5% accuracy). Collectively, these findings challenge static-exposure paradigms in MPs toxicity studies and demonstrate hydrodynamics drive MPs bioaccumulation and effects, requiring ecological risk assessment inclusion.