Carbon nanomaterial addition changes soil nematode community in a tall fescue mesocosm

Carbon nanomaterials have been widely used in industry and inevitably enter the environment. However, there is little information about their influence on the abundance and diversity of soil nematode community. We evaluated the impact of three kinds of carbon nanomaterials (graphene, graphene oxide, and carbon nanotubes) on the abundance and diversity of soil nematodes after growing tall fescue for 130 d using a laboratory pot experiment. A total of 29 genera of nematodes were identified in all the treatments. Carbon nanomaterials significantly increased the abundance of total nematodes and plant parasites. The presence of graphene and graphene oxide increased the numbers of bacterivores, and graphene benefited fungivores. The total nematode abundance was 1.9–2.9 times greater in the carbon nanomaterial treatments than in the control with no carbon nanomaterial addition. However, graphene oxide and carbon nanotubes decreased the values of nematode community parameters, e.g., diversity, species richness, and structure index. Compared with the control, the addition of graphene resulted in a community with a higher plant-parasitic index (i.e., the maturity index of the plant-parasitic nematodes). Overall, our findings highlight that the addition of carbon nanomaterials has a negative influence on the composition and diversity of the nematode community, simplifying the community structure.