Ecotoxicological assessment of microplastics: toxicity of glitter on embryos of the sand-dollar Mellita quinquiesperforata

Abstract

Plastics are considered a high priority environmental problem because they consist of one of the fastest growing forms of pollution in the world. Among the plastic residues, microplastics (MPs - small fragments ranging between 1 µm and 5 mm) are of main concern because high quantities of MPs have been found in oceans and freshwater environments. Glitter is a type of particle formed by layers of plastic polymers and metals, and has not received much attention from the scientific community regarding its polluting potential. Up to now, there are no studies and robust information about the sources, input rates, fate, presence in the environment, and possible effects of glitter on marine environments. Since glitter represents a potential pollutant, there is a need for studies on these particles. This project aims to determine the toxicity of glitter particles on embryos of the sand dollar Mellita quinquiesperforata. Adult organisms will be collected in beaches from the São Paulo State and transported to the laboratory. Then, spawning will be induced by osmotic shock (1M KCl) and gametes will be fertilized. The glitter particles will be diluted in one liter of filtered and autoclaved sea water, producing a stock solution (100 mg/L) that will kept under soft aeration. The stock solution will be diluted in filtered sea water (serial dilutions) in order to form 5 test concentrations (100, 10, 1, 0.1 and 0.01 mg/L), plus the control. Four replicates will be used per concentration. The eggs will be added to each test-tube, and after 36 hours, the embryos will be fixed with buffered formaldehyde and then examined under microscope, in order to assess the embryolarval development - normal and abnormal larvae will be counted. Subsequently, the results will be analyzed by means of analysis of variance, followed by Dunnett's test, and the effective concentration to 50% embryos (EC50) will calculated, in order to determine the toxic concentrations to the embryos of M. quinquiesperforata.