Ecotoxicological impacts of exposure to copper oxide nanoparticles on the gill of the Swan mussel, Anodonta cygnea (Linnaeus, 1758)

Abstract

ABSTRACTThis study was conducted to investigate the ecotoxicological effects of exposure to copper oxide nanoparticles (CuO NPs) on the gill of the swan mussel Anodonta cygnea using several approaches including qualitative and quantitative histopathology, ultra-morphology (scanning electron microscopy [SEM]) and measures of clearance rate (CR) and bioaccumulation of CuO NPs. Histological alterations in mussels exposed to 0.25 (T1), 2.5 (T2) and 25.0 µg L−1 (T3) CuO NPs for 12 days include changes in the length and form of gill lamellae, changes in inter-lamellar spaces, epithelial hyperplasia, atrophy and tissue rupture. Ultra-morphological changes following CuO NP exposure included epithelial hyperplasia and hypertrophy, epithelial lifting, tissue rupture (water channel fusion) and extensive necrosis of the gill surfaces. IGill (gill damage severity) index values for both histopathological and ultra-morphological data were significantly (P < 0.05) higher in T3. The CR of mussels was significantly (P < 0.05) lower in the highest exposure concentration (CR = 39.21 ± 16.85 [L min−1 g−1 dry weight]) in comparison to controls (CR = 108 ± 47.14 [L min−1 g−1 dry weight]). CuO NPs accumulated in exposed mussels at all exposure concentrations until day 4, but there was no further change in accumulation levels by the end of the exposure period. The accumulated content of CuO NPs was significantly (P < 0.05) lower in 25.0 µg L−1 exposure concentration. Based on these results, significant accumulation of CuO NPs in the gills of swan mussel could affect histological and ultra-structural characteristics of this organ and consequently have deleterious impacts on its filtration activity.