Effects Caused by the Ingestion of Microplastics: First Evidence in the Lambari Rosa (Astyanax altiparanae)

SIMPLE SUMMARY: Amongst aquatic animals, fish are potentially vulnerable to the ingestion—accidental or intentional—of microplastics (MPs) discarded in the environment, due to aspects such as their similarity to food and the buoyancy of these materials, as well as their attractive coloration. By analyzing toxicological parameters (mortality, malformations, and changes in weight gain) and monitoring the ingestion and excretion of MPs from two different polymers, it was noted that exposure to a diet containing these particles was responsible for causing mortality, as well as accumulation of the ingested MPs, which were not fully excreted and remained retained in the gastrointestinal tract of the lambari rosa fish. Therefore, the results of the current study should be combined with further research, covering different species, to improve understanding of the bioaccumulation of MPs and to help devise attempts at environmental mitigation, since the harmful potential of these particles is clear, especially for the aquatic organisms that ingest them. ABSTRACT: Microplastics are a class of contaminants that pose a threat to aquatic biota, as they are easily found in aquatic ecosystems and can be ingested by a wide variety of organisms, such as fish. The lambari rosa (Astyanax altiparanae) is a microphage fish, which feeds on microscopic beings and particles, making it potentially susceptible to ingesting MPs discarded in the environment. In addition, this fish is of great economic and food importance, as it is used for human consumption. This study aimed to evaluate the accumulation and possible toxicological effects caused to lambari rosa (n = 450) by the ingestion of polyethylene (PE) and polyethylene terephthalate (PET) MPs, since the MPs of these polymers in the form of granules, fragments, and fibers are the most commonly reported in the aquatic environment. The parameters investigated here were the quantitative analysis of ingested MPs using microscopic and staining techniques, as well as the mortality rate, malformations/injuries, and impaired weight gain. At the end of the experiment, it was concluded that MPs from both polymers accumulated in the gastrointestinal tract of the lambari rosa, and that dietary exposure, especially to the PET polymer, was responsible for increasing the mortality rate in this species.