Toxicity evaluation of graphene oxide on cysts and three larval stages of Artemia salina.

Using Artemia salina as an experimental model, the potential risks of graphene oxide (GO) to marine ecosystems were investigated. Hatchability of capsulated and decapsulated cysts, mortality of instar I, II and III larvae, and a number of morphological, ethological and physiological parameters were selected as end-points for toxicity assessment. Our results show that GO significantly decreased (p<0.01) the hatchability of capsulated and decapsulated cysts following exposure to 400 and 600mg/L for 36h. There was a concentration-dependent increase in mortality and decrease in swimming speed of larvae, and instar II larvae showed a greater sensitivity compared with instar I and instar III larvae. The LC50 values of instar II and III were 368.18 and 387.68mg/L, respectively (not calculable for instar I). The EC50 values for swimming speed alteration of instar I, II and III were 415.13, 273.50 and 289.05mg/L, respectively. Moreover, body lengths and individual dry weight of larvae (instar I, II and III) also decreased in dose-dependent manners. GO attached onto the surface of cysts and larvae, resulting in irreversible damage to the larval body surface. All of malondialdehyde content, total antioxidant capacity, reactive oxygen species and superoxide dismutase activity of A. salina larvae substantially increased in dose-dependent manners after exposure to GO suspensions, indicating that toxic effects were due to oxidative damages. However, for the activities of catalase, glutathione peroxidase and glutathione S-transferase, GO induced different effects on the larvae. Finally, the uptake result indicated that GO was ingested and concentrated in the gut, and was visible within the primary body cavity and yolk.