Response of plasma copper, ceruloplasmin, iron and ions in carp, Cyprinus carpio to waterborne copper ion and nanoparticle exposure

In this study, Cyprinus carpio was exposed to 0.25 mg L− 1 copper as either copper sulfate (CuSO4) or copper oxide nanoparticles (nano-Cu), and 25 mg L− 1 copper as nano-Cu for 14 days. CuSO4 and high concentration of nano-Cu led to a significant increase in plasma total copper levels. Plasma free copper levels increased significantly in all copper-exposed treatments. Except for low concentration of nano-Cu after 7 and 14 days, copper exposure generally led to a significant decrease in plasma ceruloplasmin levels. Plasma iron levels increased significantly in CuSO4 (all times) and nano-Cu (7th and 14th days) treatments. A significant elevation in plasma total iron binding capacity (TIBC) was observed after 3 days in the fish exposed to low concentration nano-Cu, and after 14 days in all copper-exposed treatments. Transferrin saturation (TSA) ratio showed significant increase in CuSO4 (3rd and 7th days) and the high concentration nano-Cu (7th day) treatments. Decrease in plasma chloride (7th and 14th days) and sodium (14th days) was observed in CuSO4 treatment. In conclusion, the results suggest that ionic copper is mainly absorbed via fish gill, whereas, nano-copper are more likely absorbed via gut. Also, data suggest that ionic copper has more adverse effects on the examined plasma biochemical characteristics compared to the equivalent nano-copper concentration, which may be due to the lower copper absorption by fish in the nano-copper suspension.