Dynamic Accumulation and Bio-Mediated Fragmentation of Microplastics in the Digestive System of Red Swamp Crayfish (Procambarus clarkii)

The dynamic behavior and biologically mediated transformation of microplastics (MPs) in crustaceans remain insufficiently explored in aquatic ecotoxicology. In this study, we employed the red swamp crayfish (Procambarus clarkii) as a model organism to systematically investigate the accumulation, distribution, fragmentation, and excretion kinetics of MPs within its digestive system under controlled conditions. We exposed crayfish to fluorescent polystyrene microplastics (50 μm) at a high concentration (100,000 particles/L), which exceeded typical environmental levels but was necessary to track accumulation and fragmentation dynamics within the experimental timeframe, and dissections were performed at 24, 48, and 96 h. Spatiotemporal patterns and morphological changes in MPs were analyzed using advanced microscopic imaging techniques. The results revealed a peak in MP accumulation at 48 h, followed by a decrease at 96 h, suggesting a dynamic equilibrium between ingestion and elimination. Over time, particle sizes decreased significantly, a result consistent with microplastic fragmentation. Additionally, feed supplementation during depuration was associated with increased fragmentation efficiency. Morphological analysis showed digestion-induced changes such as surface wrinkling, irregular edges, and particle shrinkage. These findings elucidate the transformation mechanisms of microplastics within crustaceans and provide crucial insights for assessing their potential ecological risks and fate as pollutants. Based on results from high-concentration short-term laboratory exposure studies, this paper further indicates the necessity for in-depth exploration into the long-term dynamics of microplastics within aquatic organisms and the potential for their transfer across trophic levels.