Occurrence and ecological impact of microplastics in aquaculture ecosystems

Extensive applications of plastic in human life has caused substantial microplastic pollution in the global environment, which, due to plastic's ubiquitous nature and everlasting ecological impact, has caused worldwide concern. In aquatic ecosystems, microplastics are ingested by aquatic animals, affecting their growth and development and resulting in trophic transfer to higher organisms in the food chain. Therefore, consumption of aquatic products is a main primary source of human exposure to microplastics. Recently, aquaculture production has experienced tremendous growth and will exceed production from fish catch soon. Because they constitute an important source of protein in the human food supply, aquaculture products contaminated with microplastics directly affect food quality and safety. The present review summarizes documented studies regarding the occurrence and distribution of microplastics in various aquaculture systems and species and compares microplastic pollution in aquaculture species and captured species. Microplastics in aquaculture environments mainly come from exogenous imports, such as plastic waste and debris from the land, tourism, shipping transportation and atmospheric deposition. In addition, the use of plastic gear and equipment, aquaculture feed and health products, and special aquaculture environments contribute to a higher accumulation of microplastics. We also discuss the adverse effects of microplastics in aquaculture species and the potential health risks of microplastics to humans through the food chain. In summary, this review highlights the effects of microplastic pollution in aquaculture, particularly the ecological impacts on aquaculture species and associated human health implications, and calls for restricted control of microplastics in aquaculture ecosystems.