Developmental toxicity in zebrafish exposed to polyethylene microplastics under static and semi-static aquatic systems.

Different studies have reported the ecotoxicological effects of polyethylene microplastics (PE MPs) on aquatic organisms; however, little is known about their toxicity in the early life stages of aquatic vertebrates living in freshwater ecosystems. Thus, the aim of the current study is to evaluate the toxicity of PE MPs throughout the development of Danio rerio after their static and semi-static exposure to different concentrations of these pollutants (6.2, 12.5, 25, 50 and 100 mg/L) - models were monitored at different time-periods, namely: 24, 48, 72, 96, 120 and 144 h. Based on the collected data, small PE MP concentrations have harmful effects on D. rerio embryos and larvae; the magnitude and characteristics of these effects depend on the adopted exposure system, which can be static or semi-static. PE MPs had negative effect on embryos' hatching rate in both exposure systems. However, the early hatching observed during the exposure through the static system could explain the lower larval survival rate after egg hatching. Nevertheless, PE MPs induced significant changes in various morphometric parameters. The present study is the first to assess the addressed topic; therefore, it is recommended to carry out future investigations to broaden the knowledge about PE MP toxicity.