Microplastics (MPs) are small, persistent pieces of plastic (<5 mm) that accumulate in various marine ecosystems worldwide, including beaches. These particles degrade habitat quality and negatively impact aquatic organisms through ingestion at all levels of the food web. This study quantified, characterized, and determined the temporal distribution of MPs in the sand of Playa San Luis, the busiest urban beach in the Gulf of Cariaco, Venezuela. The average abundance of MPs was highest during the rainy season (14.84 MPs kg–1), followed by the transitional season (11.79 MPs kg–1) and the dry season (8.16 MPs kg–1). Fibers were the most common morphology (67 %), and among these, transparent fibers were the most abundant. MPs made of polyethylene, polypropylene, polyester, and polystyrene were identified. The high presence of fibers is attributed to wastewater effluents, fragmentation of fishing gear, and clothing shed by beachgoers. The greater abundance of MPs during the rainy season suggests an intensification of the pathways for these contaminants, coinciding with holiday periods and increased river flows. The study demonstrates the presence of MPs at San Luis Beach, highlighting the need for mitigation measures and further research to understand their consequences.
