Cascading Ecological Impacts of Fullerenes in Freshwater Ecosystems.

Carbonaceous nanomaterials, such as fullerenes (C60, C70) and the derivative phenyl-C61-butyric acid methyl ester (PCBM), have promising application in solar energy technologies. Although the acute ecotoxicity of C60 has been reported widely in the literature, ecotoxicity assays for different fullerene forms and broader ecosystem impact studies remain scarce. To address these knowledge gaps, acute, chronic, and life stage exposure studies with freshwater zooplankton, Daphnia magna and Daphnia pulex, were performed for each material. Experimental results indicated that C60 and PCBM are not acutely toxic at estimated environmentally relevant concentrations; however, C70 had significant acute effects. All forms of fullerene caused a gradual elevation in heart rate over time and visual darkening of the Daphnia spp. carapace. The impact of fullerenes on susceptibility to predation was then assessed experimentally by presenting D. pulex to the visual predator Lepomis macrochirus (bluegill). Predation risk was significantly increased in fullerene-exposed D. pulex. The present study underscores the need to broaden the scope of traditional ecotoxicity for emerging materials: studies are required that evaluate portfolios of related nanomaterials and that capture chronic and cascading ecosystem-level effects. Environ Toxicol Chem 2019;38:1714-1723. © 2019 SETAC.