Ecotoxicological impacts of zinc metal in comparison to its nanoparticles in Nile tilapia; Oreochromis niloticus

Abstract

Nile tilapia; Oreochromis niloticus was used as a bio-indicator to evaluate the impact of zinc metal. The potential impacts of zinc nanoparticles (Zn NPs) on aquatic ecosystems have attracted special attention due to their unique properties. The present investigation was designed to evaluate and compare between the possible ecotoxicological effects of zinc bulk particles (BPs) and Zn NPs on O. niloticus. LC50/96 h of Zn (BPs & NPs) were (1.36 & 0.18 g/l), respectively. The concentration equivalent to 1/2 LC50/96 h of Zn BPs (0.68 g/l) and Zn NPs (0.09 g/l) was selected for 7, 14 & 28 days. Exposure of the studied fish to 1/2 LC50/96 h of Zn BPs & Zn NPs elicited a significant decrease in total lipids, total protein and globulin contents, coinciding with an enhancement in serum glucose, albumin, creatinine and uric acid concentrations, as well as activities of liver enzymes named AST, ALT, and ALP after the experimental periods. Moreover, Zn NPs significantly induced an increase in liver and gills glutathione peroxidase (GPx), catalase (CAT), superoxide dismutase (SOD) activities and malondialdehyde (MDA) levels and with concomitant decreases in the liver and gill (GSH) level in the studied fish. The adverse effects of NPs were observed to be time dependent with increasing extent during the studied time intervals, while fish groups treated with BPs showed more or less time dependent effects. In conclusion, Zn NPs have stronger toxic impacts than that of the Zn BPs, and increased with prolonged exposure time.