The toxic effects of various substances on Daphnia magna (D. magna) observed through traditional waterborne uptake may involve alterations to the nutritional quality of the contaminated algae and culture media. It is essential to find an alternative delivery method that will not affect the nutritional quality of D. magna's diet in order to elucidate the mechanisms of dietary metal toxicity. Therefore, this study examined the application of liposome encapsulation on the dietary toxicity of D. magna. Ag+-laden liposomes were prepared and the Ag encapsulation efficiency and inhibition effect on algae growth were examined. Then, acute and 14-day subchronic studies were performed to examine the effect of Ag+-laden liposomes on D. magna. The EC50 for the 24 h immobilization test was 10.59 µg/L for Ag+-laden liposomes and 3.07 µg/L for Ag+. In terms of subchronic effects, the estimated ECx values under the Ag+-laden liposome condition were always higher than the direct exposure condition. Furthermore, the bioaccumulation of Ag+-laden liposomes was about 1.68 times lower than direct exposure. Generally, Ag+-laden liposomes produced less efficient toxicity than direct exposure, e.g., lower D. magna mortality, production of more neonates, higher intrinsic rate of natural increase (rm), earlier time to first brood, and higher enzyme activities.
Keywords: Daphnia magna; Acute and subchronic toxicity; dietary toxicity; liposome; silver ions.