ZnO nanoparticles interfere with top-down effect of the protozoan paramecium on removing microcystis. (1st October 2022)

• Record Type: Journal Article
• Authors: Zhang, Lu; Yin, Wei; Shen, Siyi; Feng, Yuyun; Xu, Wenjie; Sun, Yunfei; Yang, Zhou
• Is Part Of: Environmental pollution. Volume 310(2022)
• Publication Date: 2022-10-01
• Subjects: Biological control -- Microcystis -- Nanotoxicity -- Protozoan Paramecium -- ZnO nanoparticles; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2022.119900
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: Under intensive human activity, sewage discharge causes eutrophication-driven cyanobacteria blooms as well as nanomaterial pollution. In biological control of harmful cyanobacteria, top-down effect of protozoan has great potentials for removing cyanobacterial populations, degrading cyanotoxins, and improving phytoplankton community. ZnO nanoparticles as a kind of emerging contaminants have attracted increasing attention because of wide application and their high bio-toxicity effects on reducing the ingestion of aquatic animals including Paramecium, thereby possibly disturbing top-down control of cyanobacteria. Therefore, this study investigated the effects of ZnO nanoparticles at environmental-relevant concentrations on the protozoan Paramecium removing toxic Microcystis . Results showed Paramecium effectively eliminated all the Microcystis, despite exposure to ZnO nanoparticles. However, their ingestion rate was significantly reduced at more than 0.1 mg L −1 ZnO nanoparticles, thereby delaying Microcystis removal. Nevertheless, at 0.1 mg L −1 ZnO nanoparticles, the time to Microcystis extinction decreased compared to the group without ZnO nanoparticles, because Microcystis populations were reduced under this circumstance, while ingestion rate of Paramecium was unaffected. Furthermore, ZnO nanoparticles obviously accumulated in food vacuoles of Paramecium, and the size of nanoparticles aggregates and zinc concentrations in Paramecium were increased with ZnO nanoparticles concentrations. At the end of experiment, these food vacuoles were not dissipated. Overall, these findings suggest that ZnO nanoparticles impair protozoan top-down effects through reducing Microcystis and ingestion rate as well as disturbing functions of their digestive organelles, and highlight the need to consider the interfering effects of environmental pollutants on cyanobacterial removal efficiency by protozoans in natural waters. Graphical abstract: Image 1 Highlights: Ingestion rate of Paramecium was inhibited at more than 0.1 mg L −1 ZnO NPs. ZnO NPs interfere with Microcystis removal by Paramecium ingestion. Size of ZnO NPs aggregates in Paramecium increased with NPs concentrations. With increase of ZnO NPs, Paramecium eliminating Microcystis was delayed. ZnO NPs caused morphological abnormality of food vacuoles in Paramecium. Abstract : Capsule: ZnO nanoparticles interfere with Paramecium ingesting toxic Microcystis, which may impair protozoan's top-down effect on harmful algae removal in natural waters.