Microplastics (20 µm – 5 mm) in surface waters of Cuban coral reef ecosystems analyzed by Laser Direct Infrared Imaging (LDIR)

This study is the first detailed investigation of microplastics (MPs) ranging from 20 µm to 5 mm in surface waters of coral reef ecosystems of the coast of Cuba. A total of 72 samples were collected from 22 stations during the scientific cruise "BOJEO CUBA 2024". The post-sampling treatment was based on enzymatic digestion of organic matter and subsequent analysis of the MPs using laser direct infrared (LDIR) Chemical Imaging Spectroscopy. A total of 2,616 MPs and 11 types of polymers have been identified, with a significant composition of Polypropylene accounting for 27% of the total, followed by Polyethylene (25%), Polytetrafluoroethylene (12 %), Polyurethane (11 %), and Polyethylene terephthalate (10 %). From a size perspective, 94 % of these MPs were smaller than 300 microns, indicating a significant presence of very small particles. Total number concentrations ranged from 11 to 176 microplastic particles per Liter, with an average of 75 MP L⁻¹ and a standard deviation of 41 MP L⁻¹. The spatial analysis clustered the selected sampling sites into three groups based on the abundance and polymer composition, reflecting varying levels of MP pollution and potential sources across the island.