Toxic effects on ciliates under nano-/micro-plastics coexist with silver nanoparticles

Area of Science:

• Environmental Science
• Marine Biology
• Ecotoxicology

Background:

• Microplastics (MPs) and nanoplastics (NPs) are pervasive environmental contaminants.
• Silver nanoparticles (AgNPs) pose risks to marine life due to widespread use.
• Limited data exists on the combined ecotoxicological effects of MPs/NPs and AgNPs.

Purpose of the Study:

• To investigate the combined toxicity of various sizes of polystyrene beads (MPs/NPs) and AgNPs on the marine ciliate Uronema marinum.
• To assess the impact of co-exposure on ciliate abundance, biomass, and physiological responses.
• To elucidate the molecular mechanisms underlying the combined toxicity.

Main Methods:

• Exposure of Uronema marinum to different sizes of polystyrene beads (80 nm, 220 nm, 1.07 µm, 2.14 µm) and 30 nm AgNPs, individually and in combination.
• Measurement of ciliate abundance, biovolume, and carbon biomass.
• Analysis of antioxidant enzyme activity and antioxidant content.
• Transcriptome sequencing to identify affected metabolic pathways and cellular damage.

Main Results:

• MPs/NPs significantly reduced the abundance, biovolume, and carbon biomass of U. marinum.
• Co-exposure to MPs/NPs and AgNPs exhibited synergistic toxicity, with NPs + AgNPs showing more pronounced effects than MPs + AgNPs.
• Exposure altered antioxidant enzyme activity and content, indicating oxidative stress.
• Transcriptome analysis revealed impacts on energy and lipid metabolism, DNA, and protein damage.

Conclusions:

• Combined exposure of MPs/NPs and AgNPs poses a significant threat to marine ciliated protozoa, a crucial component of marine food webs.
• Nanoplastics combined with silver nanoparticles demonstrate enhanced toxicity, impacting fundamental physiological processes and cellular integrity.
• This study provides critical data for understanding the ecotoxicological risks of combined microplastic and nanoparticle pollution in marine ecosystems.