Acute and subchronic effects of cellulose nanofibers on histological, antioxidant, and acetylcholine responses in the Mediterranean mussel (Mytilus galloprovincialis)

The utilisation of cellulose nanofibrils (CNFs) in industrial applications has seen a marked increase, giving rise to concerns regarding their potential impacts on aquatic ecosystems. The present study evaluated the acute (96 h) and sub-chronic (14 days) effects of CNFs at environmentally relevant concentrations (10, 100, and 1000 mu g/L) on the Mediterranean mussel (Mytilus galloprovincialis), a species of particular importance in marine food webs. A comprehensive analysis of the Gill and mantle tissues was conducted to ascertain any potential histopathological alterations or antioxidant responses. This analysis encompassed the measurement of superoxide dismutase (SOD), catalase (CAT), and glutathione-S-transferase (GST) activities, along with the assessment of acetylcholinesterase (AChE) activity in the mantle tissue. This approach was undertaken to evaluate the potential for neurotoxic effects. CNF exposure has been demonstrated to induce histological changes, including epithelial deformation and hemocyte infiltration, indicating oxidative damage and activation of cellular defense mechanisms. Oxidative stress parameters demonstrated a concentration-dependent increase in reactive oxygen species (ROS) under both exposure durations. AChE activity also increased, likely reflecting a compensatory response to maintain neural homeostasis. The results demonstrate that CNFs trigger coordinated antioxidant and neuroregulatory responses in M. galloprovincialis, with effects becoming more pronounced at higher concentrations and longer exposures. These findings emphasise the potential for sub-lethal effects on marine bivalves even from biodegradable nanomaterials, underscoring the necessity for comprehensive ecotoxicological assessment of nanoscale cellulose in aquatic environments and highlighting the broader implications for environmental management, regulatory policies, and safe application of nanocellulose-based products.