Tiny Plastics, Big Pressure: Nanoplastic Accumulation in Benthic Meiofauna

Nanoplastics (NPs, <1 µm) are increasingly recognized as pervasive pollutants in marine environments, not only due to their minute size and cellular permeability but also their capacity to act as vectors for other hazardous substances. These particles tend to accumulate in sediments, raising concerns about their interaction with benthic organisms, particularly meiofauna, which are crucial components of sedimentary food webs. Owing to their small size, rapid turnover, and sediment-dwelling behavior, meiofaunal taxa are potential conduits for the entry of NPs into benthic trophic networks. In this study, we explored how varying hydrostatic pressures influence the accumulation of fluorescent polystyrene nanoplastics (PS-NPs) in meiofauna community. Leveraging a novel high-pressure simulation system, organisms were exposed to three pressure regimes (0, 2500, and 5000 kPa) and two PS-NPs concentrations: 0.02 µg/L (environmentally realistic) and 20 µg/L (representing an acute exposure condition). Preliminary findings suggest that both increased pressure and higher PS-NPs concentration significantly enhance nanoparticle retention in meiofaunal organisms, particularly nematodes. These results highlight the potential for elevated pressures, typical of continental slope habitats, to modulate pollutant uptake in deep-sea ecosystems. By replicating environmental gradients, our approach offers insight into the early stages of pollutant transfer across trophic levels in benthic habitats. Continued refinement of pressure-based experimental systems could reveal further details about NPs behavior in sediment-hosted communities and support risk assessments of NPs in deep-sea marine environments, where data remain scarce.