Bioaccumulation and oxidative stress responses measured in the estuarine ragworm (Nereis diversicolor) exposed to dissolved, nano- and bulk-sized silver

The impact of Ag NPs on sediment-dwelling organisms has received relatively little attention, particularly in linking bioaccumulation to oxidative injury. The polychaete Nereis diversicolor was exposed to sediments spiked with dissolved Ag (added as AgNO₃), Ag NPs (63 ± 27 nm) and larger bulk Ag particles (202 ± 56 μm), for up to 11 days at sublethal concentrations (nominally 2.5, 5, 10 μg Ag g⁻¹ sediment (dw)). There were concentration- and time-dependent differences in the accumulation of the three Ag forms, but all three forms elicited an oxidative stress response. In the cases of Ag NPs and bulk Ag particles, changes in antioxidant markers (glutathione, SOD, CAT, GPx, SeGPx, GST and GR) occurred without significant Ag accumulation. Differences in biomarker profiles between the three Ag forms suggest that the mechanism of oxidative stress caused by particulate Ag is distinct from that of dissolved Ag. - Highlights: • N. diversicolor exposed to dissolved, nano and bulk Ag via spiked sediments. • Concentration- and time-dependent differences in the accumulation patterns. • All three forms elicited an oxidative stress response. • Antioxidant markers changed without significant accumulation for particulate Ag. • Biomarker profile resulting from particulate Ag exposure different to dissolved Ag. - Exposure to different Ag forms leads to distinct oxidative stress biomarker profiles. Particulate Ag activates the oxidative stress response differently to dissolved Ag