Microplastics in the coral reefs and their potential impacts on corals: A mini-review

Plastic debris exists worldwide and research on microplastic pollution has gradually spread from the oceans to freshwater and terrestrial systems. Coral reefs not only serve as one of the most charismatic and biodiverse ecosystems on our planet, but also maintain the human harvesting of natural resources and livelihoods of hundreds of millions of people. However, the abundance and distribution characteristics of microplastics in coral reef systems receive little scientific attention. Meanwhile, the impacts of microplastics and nanoplastics on coral health and its potential mechanisms remain further studied. Herein, this review first summarized the current status of microplastics pollution in global coral reefs, especially included (i) abundance and distribution characteristics of microplastics in different media (e.g., seawater, sediment, corals), and (ii) possible sources of microplastics in reef regions. Furthermore, the main interaction mechanisms between microplastics and corals are highlighted. Following this, the direct or indirect impacts of microplastics on coral species are discussed. With the rapid increase of plastic consumption and background of pervasive global coral bleaching, research on marine microplastics must focus on the critical coral reef regions and include a comprehensive knowledge about the distribution, fate, and potential risks from an ecosystem perspective. • Abundance and distribution of microplastics in coral reefs are firstly reviewed. • Source and characteristics of microplastics vary from different coral reef regions. • Microplastic prevalence is attributed to human activities and natural factors. • Microplastics interact with corals by active ingestion and passive surface adhesion. • Microplastic exposure influence coral physiology, energetics, growth and health.