Daphnia magna as a model animal for assessing microplastic toxicity

Microplastics, originating directly from household and industrial products or from large plastic degradation, are currently of extreme global concern. The coronavirus pandemic also increased the use of microplastics because all the protective equipment like face masks, full face shields and gloves are made up of different plastics such as polyurethane, PET, polyester and polypropylene. The face masks generally contain a lot of polypropylene in it which produces toxicity in ocean beds and great lakes during the weathering process. Actually, weathering processes lead to the fragmentation of plastics into microplastics by affecting their physicochemical properties. Microplastics are pervasive in the environment due to the delayed disposal of plastic wastes, a lack of detection tools and particular removal procedures, and a gradual disposal rate. Due to their small size (ranging from 1 μm to 5 mm) microplastics can easily be ingested. Consequently, living organisms living in the water column as well as those found in benthic zones are threatened by the presence of microplastics. In this paper, we have discussed the effects of microplastics on Daphnia magna. The filter feeder D. magna ingest microplastics and are not able to differentiate between particles of different nature. Microplastics decreased the survival rates, body growth, reproduction and immune responses in Daphnia. Sinking microplastics also decreased the swimming velocity of Daphnia during cruising and vertical swimming trajectories. In conclusion, these findings highlight the health risks of contamination of microplastics in aquatic environments and present Daphnia as a good model animal for research in the field of microplastic toxicity.