Does nanosized plastic affect aquatic fungal litter decomposition?

Nanosized plastics are an emerging concern in freshwater ecosystems, raising the question whether they put freshwater ecological processes at risk. Litter decomposition is a major ecological function in forested streams which is mainly driven by aquatic hyphomycetes. Here we investigated whether increasing concentrations (up to 102.4 mg/L) of nanosized polystyrene plastics (NPPs; 100nm) affect litter decomposition by five widely distributed species of aquatic hyphomycetes. Results showed that average litter decomposition decreased by 8% relative to the control when exposed to 102.4 mg/L NPPs. Aquatic hyphomycete species differed in their sensitivity to NPPs. The greatest inhibition of litter decomposition was found with Tetracladium marchalianum, where it dropped from 37 (control) to 16% (102.4 mg/L of NPP). Overall our study highlights the emerging risks and potential dangers of NPPs to freshwater ecosystem functioning. It also indicates that the impact of NPPs may be species specific.