Effects of nanoplastics on microalgae and their trophic transfer along food chain: Recent advances and perspectives

Nanoplastics (NPs) have drawn increasing attentions in recent years due to their potential threats to the aquatic ecosystems. Microalgae are primary producers, which play important roles in the normal functioning of ecosystems. According to the source of production and laboratory experiments, both NPs and microalgae are likely to be widely found in various water environments, so they have a great chance to interact with each other. Although tremendous efforts have been made to explore these potential interactions, a timely and critical review is still missing. In this paper, the effects of NPs on microalgae and their trophic transfer along the food chain were summarized. The toxic impact of NPs on microalgae is tightly associated with the concentrations, sizes, surface charge of NPs as well as the microalgae species. In addition, NPs could also interact with many other contaminants thus lead to combined effects on microalgae. NPs exposure might block the substance and energy exchange between microalgae and their surrounding environment, lead to shading effect on microalgae, promote reactive oxygen species (ROS) production or induce direct physical damage on microalgae, thereby inhibiting the growth of microalgae. Moreover, NPs could also be trophic transferred along the food chain through microalgae and subsequently affect the higher trophic level species. Yet important, current understanding of the interactions between NPs and microalgae is still quite limited, which needs to be further studied.