Toxicity of nanoZnO in Daphnia magna fed with ZnO containing Chlorella vulgaris and Scenedesmus dimorphus algae

Abstract

Nano ZnO is currently used in the rubber, electronics, electrical appliances, enamel, cosmetics<br />and medical industry. Whereas most studies have used the ecological toxicity of nanoparticles<br />, the toxic effects of nanoparticles in diet is not extensively explored. Because the algae<br />are at the base of the food chain, any change in their density, biomass and population, would<br />affect the food chain in aquatic ecosystems. Daphnia magna is widely used in environmental<br />pollution control measures, especially in nanoparticle toxicity tests for its short reproduction<br />time and high sensitivity. In this study, Chlorella vulgaris and Scenedesmus dimorphus algae<br />were contaminated with nano ZnO. Five treatment concentrations and three replications at any<br />concentration were compared between test and control groups and the results were analyzed by<br />Probit method. LC50 of Chlorella vulgaris and Scenedesmus dimorphus algae fed by nano ZnO<br />containing Daphnia magna was obtained at 1.78 and 2.59 mg/l levels after 96 hours respectively.<br />Moreover the NOEC (No Observed Effect concentration) and LOEC (lowest observed<br />effect concentration) were calculated as 0.17 and 0.25 mg/l for Scenedesmus dimorphus algae<br />and Chlorella respectively. Our results showed that Daphnia magna is more sensitive to a<br />diet comprising nano ZnO fed Scenedesmus dimorphus algae as compared to Scenedesmus<br />dimorphus environmentally contaminated with nano ZnO.