Microplastic pollution in marine environments: Exploring sources, sinks, and consequences with a focus on algal interactions

The widespread use of plastics and their low recycling rate has led to a very serious environmental problem, as plastics accumulate at an alarming rate, with effects that have not yet been thoroughly studied. Due to their small size, microplastics have become ubiquitous in various ecosystems. Furthermore, they enter organisms through multiple pathways, posing a threat to different species. The interaction between microplastics and algae, fundamental elements of aquatic food chains, has significant implications for the overall health of ecosystems. This review analyses the information published in scientific articles and official reports on the occurrence and effects of microplastics in the marine environment, particularly on algae, and their potential use for microplastic remediation. Results published demonstrate that despite the locations, it may seem that microplastics are present in all types of environments around the world. They are accumulated in sediments, seagrass, and throughout the food web. In marine environments, polyethylene is the most common polymer found, followed by polypropylene, with fibres and fragments being the most common forms. Several papers report different alga-microplastic in-teractions. These interactions offer opportunities for potential solutions to marine plastic pollution, as they could be used in the remediation of microplastics, due to their high adsorption capacity. However, extensive research is needed to determine the most suitable algal species, optimal conditions, practical challenges, and potential risks associated with this phycoremediation approach. The main gap in the literature is that current research often lacks precision in quantifying microplastic concentrations, which hinders the ability to accurately assess the associated risks, particularly to edible species. To address these challenges, the development of standardized protocols and reliable analytical techniques is essential. Urgent and systematic research on microplastics is needed to understand their sources, distribution, impacts and risks, to inform environmental and human health policies, and promote sustainable alternatives to plastics.