Epipelagic community as prominent biosensor for sub-micron and nanoparticles uptake: Insights from field and laboratory experiments

: Nowadays, ENMs/NPLs particles have not yet been extensively measured in the environment, but there is increased concern that this size fraction may be more widely distributed and hazardous than larger-sized particles. This study aimed to examine the bioaccumulation potential of engineered nanomaterials and nanoplastics (ENMs/NPLs) across marine food webs, focusing on plankton communities and commercial fish species (Engraulis encrasicolus and Scomber colias) from the Gulf of Naples. Laboratory experiments on plankton assemblages exposed to fluorescent polystyrene nanoplastics (PS-NPs, 100 nm) for 24h at concentrations ranging from 0.01 to 10 mg/L confirmed nanoplastic uptake in phytoplankton and zooplankton, indicating a dose-dependent internalization in plankton communities. Notably, in natural samples no particles were detected in fish muscle or liver tissues, suggesting limited translocation. Unexpectedly, titanium oxide particles (<1 μm) were found in natural phytoplankton, highlighting the potential presence of other nanoparticles in marine systems. These findings suggest that, despite detection challenges, plankton communities are major biosensors of ENMs/NPs contamination and highlight the need for ongoing environmental monitoring to assess ecological impacts and potential risks of nanoparticle bioaccumulation in marine ecosystems.