Microplastics: Potential impacts on aquatic biodiversity

Abstract

Microplastic pollution has been considered an issue of considerable concern for society and aquatic ecosystems due to plastics' unlimited applications and admirable properties. This review paper investigated various groups and sources of microplastics, their potential impacts on aquatic biodiversity, and the mitigation and treatment measures. Microplastics were grouped according to their sources as primary and secondary microplastics. Primary microplastics are generated more from land-based activities (98%) than sea-based activities (2%). Sources of primary microplastics are personal care products, industrial scrubbers, plastic powders, and microbeads, among others. While sources of secondary microplastics are losses of plastic materials during natural disasters, material lost or discarded from fishing vessels and aquaculture facilities, and oil and gas platforms, among others. Microplastics cause toxic effects, reduced food intake, delayed growth, oxidative damage, abnormal behaviour, a barrier to lipid metabolism, and affect fishes at molecular levels, causing genetic damage whereby microplastics absorb polycyclic aromatic hydrocarbons, which cause immunotoxicity, neurotoxicity and genotoxicity to marine species. Mitigation measures to reduce the microplastic pollution's effects include the removal of microbeads from personal care products, improved reuse, recycling and recovery of plastics, improved separation efficiency at wastewater treatment points and development of clean-up and bioremediation and phytoremediation techniques. Treatment methods include microfiltration, ultra-filtration, nanofiltration and reverse osmosis. Microplastics have varying effects on aquatic organisms, but these impacts can be mitigated and treated with different techniques and policy instruments. Therefore, the study recommends avoiding disposing of, reusing, recycling and recovering plastic substances in the aquatic environment for safe and clean waters.