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

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