Microplastics in Freshwaters: Implications for Aquatic Autotrophic Organisms and Fauna Health

Microplastics (MPs) represent small plastic particles with sizes between 1 μm and 5 mm, are insoluble in water, andclassified as primary (these are originally produced in small sizes) or secondary (the result of the degradation of plastic) types. MPs accumulate in all ecosystems, including freshwater environments, where they are subjected to degradation processes. Due to their ubiquitous nature, freshwater ecosystems, which have a vital importance in human life, are permanently subjected to these small plastic particles. In this context, MPs pollution is considered to be a global issue, and it is associated with toxic effects on all the elements of the freshwater environment. In this review, we present, in detail, the main physical (density, size, color, shape, and crystallinity) and chemical (chemical composition and modification of the MPs’ surface) properties of MPs, the mechanism of biodegradation, and the consequences of autotrophic organisms and fauna exposure by focusing on the freshwater environment. The toxicity mechanisms triggered by MPs are related to the critical parameters of the particles: size, concentration, type, and form, but they are also dependent on species exposed to MPs and the exposure route.