Shedding microplastics: metamorphosis as a potential detoxification mechanism for microplastics in <i>Chironomus riparius</i>

The modern era is characterized by the vast production of plastics, with aquatic ecosystems acting as major sinks for contaminants, making aquatic species highly susceptible to microplastic (MP) ingestion. Accumulation of MPs in benthic zones enables direct interaction between these particles and benthic organisms. This study utilized the Organisation for Economic Co-operation and Development chronic exposure test on Chironomus riparius larvae to assess the effects of MP concentrations ten times higher than environmentally relevant ones on life-history traits and to monitor particle presence throughout the life cycle. After digestion, MPs were counted in both adult C. riparius and exuviae. Results indicated a significant delay in developmental time, a reduction in developmental rate, and a lag in cumulative emergence in the MP-treated group even though the total emergence was not affected. Notably, exuviae retained significantly more MPs than adults, indicating metamorphosis as a potential detoxification route. These findings advance our understanding of life-stage-specific MP dynamics in freshwater invertebrates and suggest a novel mechanism for contaminant elimination via exuvial shedding.