Microplastics and silver nanoparticles compromise detrital food chains in streams through effects on microbial decomposers and invertebrate detritivores

• Published in: Chemosphere (Oxford) Vol. 367; p. 143656
• Main Authors: Trabulo, José, Pradhan, Arunava, Pascoal, Cláudia, Cássio, Fernanda
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.11.2024
• Subjects: antioxidants; Chironomus riparius; detritivores; detritus; Ecosystem functions; Enzymatic biomarkers; freshwater; fungi; invertebrates; Microplastics; Multiple stressors; Nano-silver; nanosilver; neurons; oxidative stress; particulate organic matter; personal care products; plant litter; polyethylene; probability; Stream detrital food web; streams; toxicity; Multiple stressors; Microplastics; Nano-silver; Stream detrital food web; Ecosystem functions; Enzymatic biomarkers; ecosystem functions; microplastics; enzymatic biomarkers; nano-silver; stream detrital food web; multiple stressors
• ISSN: 0045-6535; 1879-1298; 1879-1298
• DOI: 10.1016/j.chemosphere.2024.143656

Abundance of microplastics (MPs) in freshwater ecosystems has become an emerging concern due to their persistence, toxicity and potential interactions with other contaminants. Silver nanoparticles (Ag-NPs), which share common sources with MPs (e.g., personal care products), are also a subject of concern. Thus, the high probability of co-occurrence of both contaminants raises additional apprehensions. This study assessed, for the first time, the impacts of MPs and Ag-NPs, alone or in mixtures, on stream detritus food webs. Physiological and ecological responses of aquatic fungal communities, invertebrate shredders (Allogamus sp.) and collectors (Chironomus riparius) were examined. Additionally, antioxidant enzymatic responses of microbes and shredders were analyzed to unravel the mechanisms of toxicity; also, neuronal stress responses of Allogamus sp. were assessed based on the activities of cholinesterases. Organisms were exposed to environmentally realistic concentrations of polyethylene MPs, extracted from a personal care product (0.1, 0.5 and 10 mg L−1), for 7 days, in the absence or presence of Ag-NPs (0.1 mg L−1 and 1 mg L−1). The exposure to both contaminants reduced the growth rates of all tested organisms. MPs, Ag-NPs, and their mixtures led to a decrease in leaf litter decomposition by fungi and shredders. The availability of fine particulate organic matter, released by the shredders, increased when exposed to these contaminants. The negative effects of these contaminants were further strengthened by the responses of antioxidant enzymes that revealed high level of oxidative stress in both fungi and Allogamus sp. Moreover, the activities of cholinesterases showed that Allogamus sp. were under neuronal stress upon exposure to both contaminants. The impacts in mixtures were stronger than those of individual contaminants suggesting interactive effects. Overall, our study showed adverse effects of MPs and Ag-NPs across trophic levels and indicated that they may compromise key processes, such as organic matter decomposition in streams. [Display omitted] •MPs and Ag-NPs decreased leaf litter decomposition by stream microbes and shredders.•Contaminants alone or in mixtures reduced growth of fungi, shredders and collectors.•MPs, Ag-NPs, alone and in mixtures induced oxidative stress in microbes and shredders.•Contaminants increased FPOM availability and induced neuronal stress in shredders.•Exposure to mixtures induced higher ecological stress than individual contaminants.